ORCID Profile
0000-0002-9997-0650
Current Organisation
Moscow State University
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Analytical Chemistry | Separation Science | Nanomaterials | Other Chemical Sciences | Analytical Spectrometry | Separation Science | Synthesis of Materials | Sensor Technology (Chemical aspects) | Manufacturing Processes and Technologies (excl. Textiles) | Environmental Chemistry (incl. Atmospheric Chemistry) | Nanochemistry and Supramolecular Chemistry | Environmental Chemistry (Incl. Atmospheric Chemistry) | Chemical Characterisation of Materials | Technology not elsewhere classified | Chemical Oceanography | Chemical Oceanography
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Chemical Sciences | Scientific Instruments | Chemical sciences | Physical and chemical conditions | Other | Expanding Knowledge in the Environmental Sciences | Expanding Knowledge in Technology |
Related Links
Publications
Development of polydimethylsiloxane-microdiamond composite materials for application as sorptive devices
Publisher: Elsevier BV
Date: 02-2020
DOI: 10.1016/J.CHROMA.2019.460669
Abstract: The development and application of non-porous and porous sorptive rods, comprised of polydimethylsiloxane-microdiamond (PDMS-MD) composites, is reported. The PDMS-MD composites were made porous using inorganic salt (NaCl and NaHCO
Separation of transition metals on a poly-iminodiacetic acid grafted polymeric resin column with post-column reaction detection utilising a paired emitter–detector diode system
Publisher: Elsevier BV
Date: 12-2008
DOI: 10.1016/J.CHROMA.2008.08.049
Abstract: The selectivity, retention and separation of transition metals on a short (2 mm x 50 mm) column packed with a poly-iminodiacetic acid functionalised polymer 10 microm resin (Dionex ProPac IMAC-10) are presented. This stationary phase, typically used for the separation of proteins, is composed of long chain poly-iminodiacetic acid groups grafted to a hydrophilic layer surrounding a 10 microm polymeric bead. Through the use of a combination of a multi-step pH and picolinic acid gradient, the separation of magnesium, iron, cobalt, cadmium, zinc, lead and copper was possible, followed by post-column reaction with 4-(2-pyridylazo) resorcinol (PAR) and absorbance detection at 510 nm using a novel and inexpensive optical detector, comprised of two light emitting diodes with one acting as a light source and the other as a detector. Column efficiency for selective transition metals was in excess of N=10,000, with the baseline separation of seven metal cations in <3 min possible under optimised conditions. Detection limits of between 5 and 81 microg/L were possible based upon a 50 microL injection volume.
Precise and fast determination of inorganic magnesium in coccolithophore calcite
Publisher: Elsevier BV
Date: 10-2016
Geometrical Alignment of Multiple Fabrication Steps for Rapid Prototyping of Microfluidic Paper-Based Analytical Devices
Publisher: American Chemical Society (ACS)
Date: 09-11-2017
DOI: 10.1021/ACS.ANALCHEM.7B03796
Abstract: Three main fabrication steps for microfluidic paper-based analytical devices (μPADs) were fully integrated with accurate geometrical alignment between the in idual steps in a simple and rapid manner. A wax printer for creating hydrophobic barriers was integrated with an inexpensive (ca. $300) electronic craft plotter/cutter for paper cutting, followed by colorimetric reagent deposition using technical pens. The principal shortcoming in the lack of accurate and precise alignment of the features created by these three in idual fabrication steps was addressed in this work by developing appropriate alignment procedures during the multistep fabrication process. The wax printing step was geometrically aligned with the following cutting and plotting (deposition) steps in a highly accurate and precise manner using optical scanning function of the plotter/cutter based on registration marks printed on the paper using the wax printer and scanned by the plotter/cutter. The accuracy and precision of alignment in a two-dimensional plane were quantified by cutting and plotting cross-shaped features and measuring their center coordinates relative to wax printed reference lines. The average accuracy along the X- and Y-axis was 0.12 and 0.16 mm for cutting and 0.19 and 0.17 mm for plotting, respectively. The potential of this approach was demonstrated by fabricating μPADs for instrument-free determination of cobalt in waters using distance-based readout, with excellent precision (%RSD = 5.7) and detection limit (LOD) of 2.5 ng and 0.5 mg/L (mass and concentration LODs, respectively).
Accurate non-invasive determination of pKa of surface functionalised ion exchange monoliths using capacitively coupled contactless conductivity detection
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B803349H
Abstract: The use of on-column capacitively coupled contactless conductivity detection for the accurate non-invasive visualisation of the pH dependence of covalently bound boronic acid groups within a monolithic polymeric capillary column is demonstrated.
Investigation of polar organic solvents compatible with Corona Charged Aerosol Detection and their use for the determination of sugars by hydrophilic interaction liquid chromatography
Publisher: Elsevier BV
Date: 10-2012
DOI: 10.1016/J.ACA.2012.04.002
Abstract: A range of organic solvents (ethanol, isopropanol and acetone) has been investigated as alternatives to acetonitrile and methanol when used in conjunction with Corona Charged Aerosol Detection (Corona CAD). These solvents have been evaluated with regard to their effect on the response of the Corona CAD. Three dimensional response surfaces were constructed using raw data showing the relationship between detector response, analyte concentration and percentage of organic solvent in the mobile phase, using sucralose or quinine as the test analyte. The detector response was non-linear in terms of analyte concentration for all solvents tested. However, detector response varied in an approximately linear manner with percentage of organic solvent over the range 0-40% for ethanol or isopropanol and 0-80% for acetone and methanol. The chromatographic performance of the various solvents when used as aqueous-organic mobile phases was evaluated for isocratic and gradient separations of sugars and sugar alcohols by hydrophilic interaction liquid chromatography (HILIC) using an Asahipak NH2P-504E column coupled with Corona CAD detection. It was found that whilst acetonitrile provided the highest column efficiencies and lowest detection limits of the solvents studied, acetone also performed well and could be used to resolve the same number of analytes as was possible with acetonitrile. Typical efficiencies and detection limits of 5330 plates m(-1) and 1.25 μg mL(-1), respectively, were achieved when acetone was used as the organic modifier. Acetone was utilised successfully as an organic modifier in the HILIC separation of carbohydrates in a beer s le and also for a partially digested dextran s le.
Investigation of solute-wall interactions in separation of uranium(vi) and lanthanides by capillary electrophoresis using on-capillary complexation with arsenazo iii
Publisher: Wiley
Date: 1999
DOI: 10.1002/(SICI)1520-667X(1999)11:1<1::AID-MCS1>3.0.CO;2-U
Low-pressure gradient micro-ion chromatography with ultra-short monolithic anion exchange column
Publisher: Royal Society of Chemistry (RSC)
Date: 2004
DOI: 10.1039/B407483A
Abstract: A 1.0 x 0.4 cm silica based monolithic anion exchanger has been produced and evaluated for use within a miniature gradient suppressed ion chromatography system based upon low-pressure micro-scale peristaltic pumps.
Flow Analysis Method Using Chelating CIM Monolithic Disks for Monitoring Dissolved Labile Copper in Environmental Water Samples
Publisher: Informa UK Limited
Date: 09-2006
Multi-lumen capillary based trypsin micro-reactor for the rapid digestion of proteins
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8AN01330F
Abstract: In this work we evaluated a novel microreactor prepared using a surface modified, high surface-to-volume ratio multi-lumen fused silica capillary (MLC).
Enhanced physicochemical properties of polydimethylsiloxane based microfluidic devices and thin films by incorporating synthetic micro-diamond
Publisher: Springer Science and Business Media LLC
Date: 08-11-2017
DOI: 10.1038/S41598-017-15408-3
Abstract: Synthetic micro-diamond-polydimethylsiloxane (PDMS) composite microfluidic chips and thin films were produced using indirect 3D printing and spin coating fabrication techniques. Microfluidic chips containing up to 60 wt% micro-diamond were successfully cast and bonded. Physicochemical properties, including the dispersion pattern, hydrophobicity, chemical structure, elasticity and thermal characteristics of both chip and films were investigated. Scanning electron microscopy indicated that the micro-diamond particles were embedded and interconnected within the bulk material of the cast microfluidic chip, whereas in the case of thin films their increased presence at the polymer surface resulted in a reduced hydrophobicity of the composite. The elastic modulus increased from 1.28 for a PDMS control, to 4.42 MPa for the 60 wt% composite, along with a three-fold increase in thermal conductivity, from 0.15 to 0.45 W m −1 K −1 . Within the fluidic chips, micro-diamond incorporation enhanced heat dissipation by efficient transfer of heat from within the channels to the surrounding substrate. At a flow rate of 1000 μL/min, the gradient achieved for the 60 wt% composite chip equalled a 9.8 °C drop across a 3 cm long channel, more than twice that observed with the PDMS control chip.
Agglomerated polymer monoliths with bimetallic nano-particles as flow-through micro-reactors
Publisher: Springer Science and Business Media LLC
Date: 22-08-2012
Direct sector field ICP-MS determination of metal impurities in detonation nanodiamond
Publisher: Elsevier BV
Date: 08-2013
High power deep UV-LEDs for analytical optical instrumentation
Publisher: Elsevier BV
Date: 02-2018
Micellar electrokinetic chromatography of organic and peroxide-based explosives
Publisher: Elsevier BV
Date: 05-2015
DOI: 10.1016/J.ACA.2015.02.070
Abstract: CE methods have been developed for the analysis of organic and peroxide-based explosives. These methods have been developed for deployment on portable, in-field instrumentation for rapid screening. Both classes of compounds are neutral and were separated using micellar electrokinetic chromatography (MEKC). The effects of s le composition, separation temperature, and background electrolyte composition were investigated. The optimised separation conditions (25 mM sodium tetraborate, 75 mM sodium dodecyl sulfate at 25°C, detection at 200 nm) were applied to the separation of 25 organic explosives in 17 min, with very high efficiency (typically greater than 300,000 plates m(-1)) and high sensitivity (LOD typically less than 0.5 mg L(-1) around 1-1.5 μM). A MEKC method was also developed for peroxide-based explosives (10 mM sodium tetraborate, 100 mM sodium dodecyl sulfate at 25°C, detection at 200 nm). UV detection provided LODs between 5.5 and 45.0 mg L(-1) (or 31.2-304 μM), which is comparable to results achieved using liquid chromatography. Importantly, no s le pre-treatment or post-column reaction was necessary and the peroxide-based explosives were not decomposed to hydrogen peroxide. Both MEKC methods have been applied to pre-blast analysis and for the detection of post-blast residues recovered from controlled, small scale detonations of organic and peroxide-based explosive devices.
Capillary ion chromatography with on-column focusing for ultra-trace analysis of methanesulfonate and inorganic anions in limited volume Antarctic ice core samples
Publisher: Elsevier BV
Date: 08-2015
DOI: 10.1016/J.CHROMA.2015.07.034
Abstract: Preservation of ionic species within Antarctic ice yields a unique proxy record of the Earth's climate history. Studies have been focused until now on two proxies: the ionic components of sea salt aerosol and methanesulfonic acid. Measurement of the all of the major ionic species in ice core s les is typically carried out by ion chromatography. Former methods, whilst providing suitable detection limits, have been based upon off-column preconcentration techniques, requiring larger s le volumes, with potential for s le contamination and/or carryover. Here, a new capillary ion chromatography based analytical method has been developed for quantitative analysis of limited volume Antarctic ice core s les. The developed analytical protocol applies capillary ion chromatography (with suppressed conductivity detection) and direct on-column s le injection and focusing, thus eliminating the requirement for off-column s le preconcentration. This limits the total s le volume needed to 300μL per analysis, allowing for triplicate s le analysis with <1mL of s le. This new approach provides a reliable and robust analytical method for the simultaneous determination of organic and inorganic anions, including fluoride, methanesulfonate, chloride, sulfate and nitrate anions. Application to composite ice-core s les is demonstrated, with coupling of the capillary ion chromatograph to high resolution mass spectrometry used to confirm the presence and purity of the observed methanesulfonate peak.
Reversed phase high performance liquid chromatographic determination of dissolved aluminium in open ocean seawater
Publisher: Wiley
Date: 11-2012
Investigation on Selectivity of Mercaptopropylsilica and Silver Nanoparticles- Functionalised Mercaptopropylsilica
Publisher: Bentham Science Publishers Ltd.
Date: 30-07-2015
Chapter 5 - Elemental analysis of nanodiamonds by inductively coupled plasma hyphenated methods
Publisher: Elsevier
Date: 2017
Chelation ion chromatography of metal ions using an ODS reversed-phase column and a mobile phase containing methylthymol blue
Publisher: Elsevier BV
Date: 11-1998
Investigating the Effect of Column Geometry on Separation Efficiency using 3D Printed Liquid Chromatographic Columns Containing Polymer Monolithic Phases
Publisher: American Chemical Society (ACS)
Date: 22-12-2018
DOI: 10.1021/ACS.ANALCHEM.7B03778
Abstract: Effect of column geometry on the liquid chromatographic separations using 3D printed liquid chromatographic columns with in-column polymerized monoliths has been studied. Three different liquid chromatographic columns were designed and 3D printed in titanium as 2D serpentine, 3D spiral, and 3D serpentine columns, of equal length and i.d. Successful in-column thermal polymerization of mechanically stable poly(BuMA-co-EDMA) monoliths was achieved within each design without any significant structural differences between phases. Van Deemter plots indicated higher efficiencies for the 3D serpentine chromatographic columns with higher aspect ratio turns at higher linear velocities and smaller analysis times as compared to their counterpart columns with lower aspect ratio turns. Computational fluid dynamic simulations of a basic monolithic structure indicated 44%, 90%, 100%, and 118% higher flow through narrow channels in the curved monolithic configuration as compared to the straight monolithic configuration at linear velocities of 1, 2.5, 5, and 10 mm s
Rapid on-line preconcentration and suppressed micro-bore ion chromatography of part per trillion levels of perchlorate in rainwater samples
Publisher: Elsevier BV
Date: 05-2006
DOI: 10.1016/J.ACA.2006.01.038
Abstract: The development of a rapid method for the determination of perchlorate in rain and drinking waters is presented. In the optimised method, an on-line preconcentration technique was employed utilising a 10 mm x 4.6 mm Phenomenex Onyx monolithic guard cartridge coated with (N-dodecyl-N,N-dimethylammonio)undecanoate for selective preconcentration, with subsequent elution into a fixed volume injection loop ('heart-cut' of the concentrator column eluate) and separation using an IonPac AS16 (250 mm x 2mm) anion exchange column and a potassium hydroxide concentration gradient. Off-line optimisation studies showed that the coated monolith displayed near quantitative recovery up to 50 microg/L perchlorate level from standards prepared in reagent water. On-line preconcentration of perchlorate obtained detection limits down to 56 ng/L in reagent water, between 70 and 80 ng/L in rainwater s les and 2.5 microg/L in non-pretreated drinking water. After an additional s le sulphate/carbonate removal step, low ng/L perchlorate concentrations could also be observed in drinking water. The complete on-line method exhibited reproducibility for n=10 replicate runs of R.S.D.< or =3% for peak height/area and R.S.D.=0.08% for retention time. The optimised method, of 20 min total duration, was applied to the determination of perchlorate by standard addition in 10 rainwater s les and one drinking water s le. Concentrations of perchlorate present ranged from below the detection limit for four rainwater s les, with another three s les showing perchlorate present at between 70 and 100 ng/L, and one s le showing perchlorate present at 2.8 microg/L. Levels of 1.1 microg/L in the drinking water s le were also recorded.
Separation of inorganic anions on a high capacity porous polymeric monolithic column and application to direct determination of anions in seawater
Publisher: Wiley
Date: 08-2008
Abstract: A commercially available 4.6 mm id x 50 mm polymethacrylate-based monolithic strong anion exchange column (ProSwift SAX-1S) designed for the separation of proteins has been successfully used to separate small inorganic anions in the presence of a seawater s le matrix. Using a hydroxide eluent with suppressed conductivity detection the ion exchange capacity of this column declined over time however, using KCl as the eluent, the column performance was stable with a capacity of 530 microequiv. for nitrate. The optimum conditions for the separation of iodate, bromate, nitrite, bromide and nitrate were assessed by constructing van Deemter plots using 1.00 and 0.100 M KCl. Efficiencies of up to 26 700 plates/m were recorded using 1.00 M KCl, at a flow rate of 0.20 mL/min but iodate was not baseline resolved from the void peak. By reducing the concentration of the eluent to 0.100 M, efficiencies of up to 39 900 plates/m could be obtained at 0.35 mL/min. By employing a linear gradient ranging from 0.05 to 1.00 M KCl the ions dissolved in distilled water or a salt water matrix could be baseline separated in less than 3 min at a flow rate of 2.50 mL/min.
Chromatographic methods for the isolation, separation and characterisation of dissolved organic matter
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5EM00223K
Abstract: This review presents an overview of the separation techniques applied to the complex challenge of dissolved organic matter characterisation.
Enhanced organic species identification via laser structuring of carbon monolithic surfaces
Publisher: Elsevier BV
Date: 11-2019
Application of photo degradation for remediation of cyclic nitramine and nitroaromatic explosives
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6RA12565D
Abstract: Photo degradation is a rapid and safe remediation process and advances in continuous-flow photochemistry can scale-up yields of photo degradation.
On-line simultaneous and rapid separation of anions and cations from a single sample using dual-capillary sequential injection-capillary electrophoresis
Publisher: Elsevier BV
Date: 06-2013
DOI: 10.1016/J.ACA.2013.03.027
Abstract: A novel capillary electrophoresis (CE) approach has been developed for the simultaneous rapid separation and identification of common environmental inorganic anions and cations from a single s le injection. The method utilised a sequential injection-capillary electrophoresis instrument (SI-CE) with capacitively-coupled contactless conductivity detection (C(4)D) constructed in-house from commercial-off-the-shelf components. Oppositely charged analytes from a single s le plug were simultaneously injected electrokinetically onto two separate capillaries for independent separation and detection. Injection was automated and may occur from a syringe or be directly coupled to an external source in a continuous manner. Software control enabled high s le throughput (17 runs per hour for the target analyte set) and the inclusion of an isolation valve allowed the separation capillaries to be flushed, increasing throughput by removing slow migrating species as well as improving repeatability. Various environmental and industrial s les (subjected only to filtering) were analysed in the laboratory with a 3 min analysis time which allowed the separation of 23 inorganic and small organic anions and cations. Finally, the system was applied to an extended automated analysis of Hobart Southern Water tap water for a period of 48 h. The overall repeatability of the migration times of a 14 analyte standard s le was less than 0.74% under laboratory conditions. LODs ranged from 5 to 61 μg L(-1). The combination of automation, high confidence of peak identification, and low limits of detection make this a useful system for the simultaneous identification of a range of common inorganic anions and cations for discrete or continuous monitoring applications.
Microwave-assisted purification of detonation nanodiamond
Publisher: Elsevier BV
Date: 09-2014
3D printed LED based on-capillary detector housing with integrated slit
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.ACA.2017.02.020
Abstract: A 3D printed photometric detector body with integrated slit was fabricated to position a LED and photodiode either side of capillary tubing using a fused deposition modelling (FDM) printer. To make this approach suitable for capillaries down to 50 μm i.d. the dimension of the in-built slit is the critical element of the printed housing. The spatial orientation of the model for printing was found to significantly impact on the resolution of the structures and voids that can be printed. By designing a housing with a slit positioned in the XY plane in parallel with the print direction, the narrowest void (slit) that could be printed was 70 μm. The potential use of the 3D printed slit for photometric detection was characterised using tubing and capillary from 500 down to 50 μm i.d, demonstrating a linear response from 632 to 40 mAU. The effective pathlength and stray light varied from 383 to 22 μm and 3.8% - 50% for 500- 50 μm i.d tubing and capillary. The use of a V-shaped alignment feature allowed for easy and reliable positioning of the tubing inside the detector, as demonstrated by a RSD of 1.9% (n = 10) in peak height when repositioning the tubing between measurements using flow injection analysis (FIA). The performance of the 3D printed housing and 70 μm slit was benchmarked against a commercially available interface using the CE separation of Zn
Novel ion chromatographic stationary phases for the analysis of complex matrices
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B406355B
Abstract: Ion chromatography (IC) has a proven track record in the determination of inorganic and organic anions and cations in complex matrices. Recently, application of IC to the separation and determination of bio-molecules such as amino acids, carbohydrates, nucleotides, proteins and peptides has also received much attention. The key to the determination of all of the above species in the most analytically challenging complex matrices is the ability to manipulate selectivity through control of stationary phase chemistry, mobile phase chemistry and the choice of detection method. This Tutorial Review summarises some of the most significant recent advances made in IC stationary phase technology. In particular, the review details stationary phases specifically designed for ion analysis in complex s le matrices, and considers in which direction future stationary phase development might proceed.
Simultaneous Analysis of Inorganic Monovalent Anions/Cations Using Mixed-Bed Single-Column Ion Chromatography
Publisher: Springer Science and Business Media LLC
Date: 17-12-2014
Novel integrated paired emitter-detector diode (PEDD) as a miniaturized photometric detector in HPLC
Publisher: Royal Society of Chemistry (RSC)
Date: 2006
DOI: 10.1039/B602846B
Abstract: A novel low power, low cost, highly sensitive, miniaturized light emitting diode (LED) based flow detector has been used as optical detector for the detection of s le components in high performance liquid chromatography (HPLC). This colorimetric detector employs two LEDs, one operating in normal mode as a light source and the other is reverse biased to work as a light detector. Instead of measuring the photocurrent directly, a simple timer circuit is used to measure the time taken for the photocurrent generated by the emitter LED (lambda(max) 500 nm) to discharge the detector LED (lambda(max) 621 nm) from 5 V (logic 1) to 1.7 V (logic 0) to give digital output directly without using an A/D converter. Employing a post-column reagent method, a Nucleosil 100-7 column (functionalized with iminodiacetic acid (IDA) groups) was used to separate a mixture of transition metal complexes, manganese(II) and cobalt(II) in 4-(2-pyridylazo)-resorcinol (PAR). All optical measurements were taken by using both the in-built HPLC variable wavelength detector and the proposed paired-emitter-detector-diode (PEDD) optical detector configured in-line for data comparison. The concentration range investigated using the PEDD was found to give a linear response to the Mn(II) and Co(II) PAR complexes. The effects of flow rate and emitter LED light source intensity were investigated. Under optimised conditions the PEDD detector offered a linear range of 0.9-100 microM and LOD of 0.09 microM for Mn-PAR complex. A linear range of 0.2-100 microM and LOD of 0.09 microM for Co-PAR complex was achieved.
Chromatographic performance of synthetic polycrystalline diamond as a stationary phase in normal phase high performance liquid chromatography
Publisher: Elsevier BV
Date: 04-2015
DOI: 10.1016/J.CHROMA.2015.02.069
Abstract: The chromatographic properties of high pressure high temperature synthesised diamond (HPHT) are investigated in normal phase mode of high performance liquid chromatography. Purified nonporous irregular shape particles of average particles size 1.2 μm and specific surface area 5.1 m(2) g(-1) were used for packing 100×4.6 mm ID or 50×4.6 mm ID stainless steel columns. The retention behaviour of several classes of compounds including alkyl benzenes, polyaromatic hydrocarbons (PAH), alkylphenylketones, phenols, aromatic acids and bases were studied using n-hexane-2-propanol mixtures as mobile phase. The results are compared with those observed for microdispersed sintered detonation nanodiamond (MSDN) and porous graphitic carbon (PGC). HPHT diamond revealed distinctive separation selectivity, which is orthogonal to that observed for porous graphitic carbon while selectivities of HPHT diamond and microdispersed sintered detonation nanodiamonds are similar. Owing to non-porous particle nature, columns packed with high pressure high temperature diamond exhibited excellent mass transfer and produce separations with maximum column efficiency of 128,200 theoretical plates per meter.
Diamond based adsorbents and their application in chromatography
Publisher: Elsevier BV
Date: 08-2014
DOI: 10.1016/J.CHROMA.2014.06.044
Abstract: The idea of using diamond and diamond containing materials in separation sciences has attracted a strong interest in the past decade. The combination of a unique range of properties, such as chemical inertness, mechanical, thermal and hydrolytic stability, excellent thermal conductivity with minimal thermal expansion and intriguing adsorption properties makes diamond a promising material for use in various modes of chromatography. This review summarises the recent research on the preparation of diamond and diamond based stationary phases, their properties and chromatographic performance. Special attention is devoted to the dominant retention mechanisms evident for particular diamond containing phases, and their subsequent applicability to various modes of chromatography, including chromatography carried out under conditions of high temperature and pressure.
Ion exchange properties of monolithic and particle type iminodiacetic acid modified silica
Publisher: Wiley
Date: 07-2004
Abstract: A 10 cm silica monolith has been modified with iminodiacetic acid (IDA) groups and characterised for its selectivity toward alkali, alkaline earth, and selected transition metal cations. Physical characterisation of the modified monolith found non‐homogeneous modification along the length of the monolith, although sufficient capacity was achieved to facilitate significant retention of alkaline earth and transition/heavy metal ions over a range of eluent pH and ionic strength conditions. For alkaline earth and transition/heavy metal ions, selectivity of the 10 cm IDA monolith closely matched that seen with a 25 cm IDA modified silica gel particle packed column, although the separation of alkali metal ions was noticeably poorer on the monolithic column. Peak efficiencies for most metal ions were of a similar order for both column types, except for Zn(II), which showed significant peak broadening on the IDA monolithic column.
Porous, High Capacity Coatings for Solid Phase Microextraction by Sputtering
Publisher: American Chemical Society (ACS)
Date: 19-01-2016
DOI: 10.1021/ACS.ANALCHEM.5B03181
Abstract: We describe a new process for preparing porous solid phase microextraction (SPME) coatings by the sputtering of silicon onto silica fibers. The microstructure of these coatings is a function of the substrate geometry and mean free path of the silicon atoms, and the coating thickness is controlled by the sputtering time. Sputtered silicon structures on silica fibers were treated with piranha solution (a mixture of concd H2SO4 and 30% H2O2) to increase the concentration of silanol groups on their surfaces, and the nanostructures were silanized with octadecyldimethylmethoxysilane in the gas phase. The attachment of this hydrophobic ligand was confirmed by X-ray photoelectron spectroscopy and contact angle goniometry on model, planar silicon substrates. Sputtered silicon coatings adhered strongly to their surfaces, as they were able to pass the Scotch tape adhesion test. The extraction time and temperature for headspace extraction of mixtures of alkanes and alcohols on the sputtered fibers were optimized (5 min and 40 °C), and the extraction performances of SPME fibers with 1.0 or 2.0 μm of sputtered silicon were compared to those from a commercial 7 μm poly(dimethylsiloxane) (PDMS) fiber. For mixtures of alcohols, aldehydes, amines, and esters, the 2.0 μm sputtered silicon fiber yielded signals that were 3-9, 3-5, 2.5-4.5, and 1.5-2 times higher, respectively, than those of the commercial fiber. For the heavier alkanes (undecane-hexadecane), the 2.0 μm sputtered fiber yielded signals that were approximately 1.0-1.5 times higher than the commercial fiber. The sputtered fibers extracted low molecular weight analytes that were not detectable with the commercial fiber. The selectivity of the sputtered fibers appears to favor analytes that have both a hydrophobic component and hydrogen-bonding capabilities. No detectable carryover between runs was noted for the sputtered fibers. The repeatability (RSD%) for a fiber (n = 3) was less than 10% for all analytes tested, and the between-fiber reproducibility (n = 3) was 0-15%, generally 5-10%, for all analytes tested. The repeatabilities of our sputtered fibers and the commercial 7 μm PDMS fiber are essentially the same. Fibers could be used for at least 300 extractions without loss of performance. More than 50 compounds were identified in a gas chromatography-mass spectrometry headspace analysis of a real world botanical s le with the 2.0 μm fiber.
On-line preconcentration of pharmaceutical residues from large volume water samples using short reversed-phase monolithic cartridges coupled to LC-UV-ESI-MS
Publisher: Elsevier BV
Date: 12-2006
DOI: 10.1016/J.TALANTA.2006.02.026
Abstract: A simplified preconcentration method for a range of ultra-trace level pharmaceuticals in natural waters has been developed. Solid phase extraction was performed on-line using a micro-reversed-phase monolithic silica column, allowing for very rapid trace enrichment from large volume (500ml) s les with minimal s le handling. Acceptable recoveries of >70% were obtained for the majority of compounds investigated and the monolithic columns could be washed and conditioned on-line with no s le carryover and used reproducibly for up to eight extractions each. The on-line SPE-LC-UV method was coupled to electrospray ionisation ion trap mass spectrometry (ESI-MS) to increase both selectivity and specificity. Detection limits were determined in spiked river and tap water s les and found to lie in the low ng/l region using s le volumes of 500ml, loaded at a flow rate of 10ml/min, and therefore, were suitable for ultra trace analysis.
New possibilities in ion chromatography using porous monolithic stationary-phase media
Publisher: Elsevier BV
Date: 04-2005
Flow-dependent separation selectivity for organic molecules on metal-organic frameworks containing adsorbents
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CC00111D
Abstract: A new effect was discovered which allows changes of selectivity by variation of the mobile phase flow rate.
Ion-exchange properties of microdispersed sintered detonation nanodiamond
Publisher: Springer Science and Business Media LLC
Date: 07-03-2016
Ion Chromatography
Publisher: Elsevier
Date: 2013
Fabrication and characterisation of gold nano-particle modified polymer monoliths for flow-through catalytic reactions and their application in the reduction of hexacyanoferrate
Publisher: Springer Science and Business Media LLC
Date: 31-10-2013
High sensitivity deep-UV LED-based z-cell photometric detector for capillary liquid chromatography
Publisher: Elsevier BV
Date: 11-2018
DOI: 10.1016/J.ACA.2018.06.005
Abstract: A new high sensitivity deep-UV LED photometric detector with a z-type flow cell (45 nL or 180 nL) for miniaturised and portable capillary liquid chromatography (LC) was designed and fabricated to overcome sensitivity limitations due to short pathlength in on-capillary detectors. The new detector has a 10 mm geometric pathlength and uses high intensity light-emitting diodes (LED) as light sources in the deep-UV range (254 nm and 280 nm). No optical reference was necessary due to the low drift in the signal. Stray light was minimized by the use of an adjustable slit with a 0.5 mm pinhole. The direct relationship between absorbance and concentration was obtained using dichromate to evaluate the sensitivity and the linearity range of the detector. Performance of the miniaturised version was compared with that obtained from a commercial benchtop detector for capillary LC under the same conditions using the same optical z-cell. The miniaturised version exhibited a superior performance across all parameters, including 3 times higher effective pathlength, 4 times higher upper limit of detector linearity, and 2-5 times lower stray light levels. An application of the new detector was shown with the detection of l-dopa, l-tyrosine, norfenefrine, phenylephrine and tyramine, separated using capillary LC. The baseline noise level recorded was as low as 3.9 μAU. Further, the detector was applied in a miniaturised capillary LC for the indirect detection of common inorganic anions. In comparison to an on-capillary LED detector applied under similar chromatographic conditions, there was a 50 times higher signal to noise (S/N) ratio.
Comparison of cation-exchange capillary columns used for ion chromatographic separation of biogenic amines
Publisher: Elsevier BV
Date: 10-2018
DOI: 10.1016/J.CHROMA.2018.08.021
Abstract: The selectivity for 15 biogenic amines and amino acids shown by three capillary cation-exchange columns, IonPac CS19, CS12A and CS17 (250 × 0.4 mm ID, all from Thermo Fisher Scientific), exhibiting medium, medium low and ultra-low hydrophobicity, and either carboxylic or mixed carboxylic hosphonic acid functional groups, was investigated. A mixed mode retention mechanism was revealed with ion-exchange, hydrophobic and hydrogen bonding interactions contributing to retention of polar organic molecules on these phases. The relative impact of these interactions was evaluated via the effect of concentration and pH of the eluent (methanesulfonic acid) on the retention of fifteen structurally similar biogenic amines and amino acids. Strong hydrogen bonding interactions were observed between the solute amino acid carboxylic groups and cation-exchange groups from the ion-exchangers. This is the first time retention data correlated with logP data has revealed clustering of the solutes in two groups, according to the presence or absence of a carboxylic acid functional group. In addition, stronger retention behaviour was found for the IonPac CS12A cation-exchanger, containing both carboxylic and phosphonic functional groups. Further assessment of the orthogonality plots of retention factors for the three stationary phases revealed that the columns exhibited different complimentary selectivity that can be utilised to achieve specific separations.
Capillary zone electrophoresis of graphene oxide and chemically converted graphene
Publisher: Elsevier BV
Date: 11-2010
DOI: 10.1016/J.CHROMA.2010.09.069
Abstract: The preparation of processable graphene oxide colloids called chemically converted graphene (CCG) involves the following steps: oxidation of graphite to form graphite oxide exfoliation of graphite oxide to form graphene oxide (GO) and reduction of GO to form CCG. In this work, the exfoliation and reduction steps were monitored by capillary zone electrophoresis (CZE). CZE was performed in fused silica capillaries with UV absorbance at 230 nm (GO) and 270 nm (CCG) using 250 μM tetrapropylammonium hydroxide (pH 10.4). The results indicate that almost complete exfoliation of graphite oxide (0.05 wt%) and higher recovery of CCG were obtained by sonication at 50% power for more than 15 h. CZE is considered a valuable tool for the fractionation and analysis of GO nanoparticles and, hence, for the control of different steps in preparation of CCG.
Phytoplankton calcification as an effective mechanism to alleviate cellular calcium poisoning
Publisher: Copernicus GmbH
Date: 13-11-2202
Abstract: Abstract. Marine phytoplankton have developed the remarkable ability to tightly regulate the concentration of free calcium ions in the intracellular cytosol at a level of ~ 0.1 μmol L−1 in the presence of seawater Ca2+ concentrations of 10 mmol L−1. The low cytosolic calcium ion concentration is of utmost importance for proper cell signalling function. While the regulatory mechanisms responsible for the tight control of intracellular Ca2+ concentration are not completely understood, phytoplankton taxonomic groups appear to have evolved different strategies, which may affect their ability to cope with changes in seawater Ca2+ concentrations in their environment on geological timescales. For ex le, the Cretaceous (145 to 66 Ma), an era known for the high abundance of coccolithophores and the production of enormous calcium carbonate deposits, exhibited seawater calcium concentrations up to 4 times present-day levels. We show that calcifying coccolithophore species (Emiliania huxleyi, Gephyrocapsa oceanica and Coccolithus braarudii) are able to maintain their relative fitness (in terms of growth rate and photosynthesis) at simulated Cretaceous seawater calcium concentrations, whereas these rates are severely reduced under these conditions in some non-calcareous phytoplankton species (Chaetoceros sp., Ceratoneis closterium and Heterosigma akashiwo). Most notably, this also applies to a non-calcifying strain of E. huxleyi which displays a calcium sensitivity similar to the non-calcareous species. We hypothesize that the process of calcification in coccolithophores provides an efficient mechanism to alleviate cellular calcium poisoning and thereby offered a potential key evolutionary advantage, responsible for the proliferation of coccolithophores during times of high seawater calcium concentrations. The exact function of calcification and the reason behind the highly ornate physical structures of coccoliths remain elusive.
Zinc marine biogeochemistry in seawater: a review
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/MF11286
Abstract: The interest in trace element biogeochemistry has arisen from the well demonstrated iron hypothesis that revealed the central role that iron exerts on oceanic primary and associated biogeochemical cycles. The essentiality of zinc for key biological enzymes, coupled with a nutrient-like vertical distribution with low dissolved concentrations in many marine surface waters, provided motivation to study zinc in marine systems. Laboratory studies have confirmed the importance of zinc to sustain phytoplankton growth and its influence on the composition of the phytoplankton community. However, mixed results were obtained in the field, which suggest a more subtle effect of zinc on oceanic phytoplankton growth than iron. As a consequence, consensus on its biological role, mechanisms at play or regional versus global relevance is currently lacking and highlights the need for new conceptual models of zinc in marine systems. The recent GEOTRACES program is generating new data approaches to discuss and understand further zinc behaviour in the ocean.
Assessing the extent, stability, purity and properties of silanised detonation nanodiamond
Publisher: Elsevier BV
Date: 12-2015
Paired emitter–detector diode detection with dual wavelength monitoring for enhanced sensitivity to transition metals in ion chromatography with post-column reaction
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B812612G
Abstract: The combination of post-column derivatisation and visible detection are regularly employed in ion chromatography (IC) to detect poorly absorbing species. Although this mode is often highly sensitive, one disadvantage is the increase in repeating baseline artifacts associated with out-of-sync pumping systems. The work presented here will demonstrate the use of a second generation design paired emitter-detector diode (PEDD-II) detection mode offering enhanced sensitivity to transition metals in IC by markedly reducing this problem and also by improving signal noise. First generation designs demonstrated the use of a single integrated PEDD detector cell as a simple, small (15 x 5 mm), highly sensitive, low cost photometric detector for the detection of metals in IC. The basic principle of this detection mode lies in the employment of two linear light emitting diodes (LEDs), one operating in normal mode as a light source and the other in reverse bias serving as a light detector. The second generation PEDD-II design showed increased sensitivity for Mn(II)- and Co(II)-2-(pyridylazo)resorcinol (PAR) complexes as a result of two simultaneously acquiring detection cells--one analytical PEDD cell and one reference PEDD cell. Therefore, the PEDD-II employs two wavelengths whereby one monitors the analyte reaction product and the second monitors a wavelength close to the isosbestic point. The optimum LED wavelength to be used for the analytical cell was investigated to maximise peak response. The fabrication process for both the analytical and reference PEDD cells was validated by determining the reproducibility of detectors within a batch. The reproducibility and sensitivity of the PEDD-II detector was then investigated using signals obtained from both intra- and inter-day chromatograms.
Separation and characterisation of detonation nanodiamond by capillary zone electrophoresis
Publisher: Wiley
Date: 26-05-2014
Abstract: A new method for the characterisation of purified detonation nanodiamond (DND) using CZE has been developed. The influence of BGE conditions on electrophoretic mobility, peak shape and particle aggregation was investigated, with resultant observations supported by zeta potential approximations and particle size measurements. Sodium tetraborate (pH 9.3), Tris (pH 9.3) and sodium phosphate (pH 7) were used in studying the BGE concentration effect on a commercial source of chemically stabilised DND. The BGE concentration had a strong effect on the stability of DND in suspension. The formation of aggregates of various sizes was observed as BGE concentration increased. The effect of pH on the electromigration of DND was examined using sodium phosphate (pH 8 and 10). The CZE method was subsequently applied to four different DND s les, which had undergone different routes of purification following detonation synthesis. Each s le produced a unique electrophoretic peak or profile in sodium tetraborate buffer (pH 9.3), such that the actual separation of DND s les from different sources could be achieved.
Use of temperature programming to improve resolution of inorganic anions, haloacetic acids and oxyhalides in drinking water by suppressed ion chromatography
Publisher: Elsevier BV
Date: 04-2005
DOI: 10.1016/J.CHROMA.2005.03.028
Abstract: Temperature programming was used to improve selectivity in the suppressed ion chromatographic (IC) separation of inorganic anions, haloacetic acids and oxyhalides in drinking water s les when using NaOH gradient elution. The programme exploited varying responses of these anions to changes in temperature. Heats of adsorption (deltaH, kJ/mol) for 17 anionic species were calculated from van't Hoff plots. For haloacetic acids, both the degree of substitution and log P (log of n-octanol-waterpartition coefficient) values correlated well with the magnitude of the temperature effect, with monochloro- and monobromoacetic acids showing the largest effect (deltaH= -10.4 to -10.7 kJ/mol), dichloro- and dibromoacetic acids showing a reduced effect (deltaH= -6.8 to -8.4 kJ/mol) and trichloro-, bromodichloro- and chlorodibromoacetic acids showing the least effect (deltaH= -4.7 to -2.4 kJ/mol). The effect of temperature on oxyhalides ranged from deltaH= 8.4 kJ/mol for perchlorate to deltaH= -9.1 kJ/mol for iodate. The effectiveness of two commercial column ovens was investigated for the application of temperature gradients during chromatographic runs, with the best system applied to improve the resolution of closely retained species at the start, middle and end of the separation obtained using a previously optimised hydroxide gradient, in a real drinking water s le matrix. Retention time reproducibility of the final method ranged from 0.62 to 3.18% RSD (n = 30) showing temperature programming is indeed a practically important parameter to manipulate resolution.
Comment on ?Structural characterization of dissolved organic matter: a review of current techniques for isolation and analysis? by E. C. Minor, M. M. Swenson, B. M. Mattson, and A. R. Oyler, Environ. Sci.: Processes Impacts, 2014, 16, 2064
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4EM00631C
Abstract: This letter discusses the origins of certain components of dissolved organic matter.
Comprehensive analysis of pharmaceutical products using simultaneous mixed-mode (ion-exchange/reversed-phase) and hydrophilic interaction liquid chromatography
Publisher: Wiley
Date: 30-06-2014
Abstract: Liquid chromatographic assays were developed using a mixed-mode column coupled in sequence with a hydrophilic interaction liquid chromatography column to allow the simultaneous comprehensive analysis of inorganic/organic anions and cations, active pharmaceutical ingredients, and excipients (carbohydrates). The approach utilized dual s le injection and valve-mediated column switching and was based upon a single high-performance liquid chromatography gradient pump. The separation consisted of three distinct sequential separation mechanisms, namely, (i) ion-exchange, (ii) mixed-mode interactions under an applied dual gradient (reversed-phase/ion-exchange), and (iii) hydrophilic interaction chromatography. Upon first injection, the Scherzo SS C18 column (Imtakt) provided resolution of inorganic anions and cations under isocratic conditions, followed by a dual organic/salt gradient to elute active pharmaceutical ingredients and their respective organic counterions and potential degradants. At the top of the mixed-mode gradient (high acetonitrile content), the mobile phase flow was switched to a preconditioned hydrophilic interaction liquid chromatography column, and the standard/s le was reinjected for the separation of hydrophilic carbohydrates, some of which are commonly known excipients in drug formulations. The approach afforded reproducible separation and resolution of up to 23 chemically erse solutes in a single run. The method was applied to investigate the composition of commercial cough syrups (Robitussin®), allowing resolution and determination of inorganic ions, active pharmaceutical ingredients, excipients, and numerous well-resolved unknown peaks.
Chromatographic behaviour of synthetic high pressure high temperature diamond in aqueous normal phase chromatography
Publisher: Elsevier BV
Date: 10-2016
DOI: 10.1016/J.CHROMA.2016.09.076
Abstract: The chromatographic properties of high pressure high temperature synthesised diamond (HPHT) are investigated under the conditions of hydrophilic interaction liquid chromatography (HILIC). A 50×4.6mm ID stainless steel column packed with HPHT particles of mean diameter 1.6μm and specific surface area 5.1m
The importance of chain length for the polyphosphate enhancement of acidic potassium permanganate chemiluminescence
Publisher: Elsevier BV
Date: 09-2014
DOI: 10.1016/J.ACA.2014.07.012
Abstract: Sodium polyphosphate is commonly used to enhance chemiluminescence reactions with acidic potassium permanganate through a dual enhancement mechanism, but commercially available polyphosphates vary greatly in composition. We have examined the influence of polyphosphate composition and concentration on both the dual enhancement mechanism of chemiluminescence intensity and the stability of the reagent under analytically useful conditions. The average chain length (n) provides a convenient characterisation, but materials with similar values can exhibit markedly different distributions of phosphate oligomers. There is a minimum polyphosphate chain length (∼6) required for a large enhancement of the emission intensity, but no further advantage was obtained using polyphosphate materials with much longer average chain lengths. Providing there is a sufficient average chain length, the optimum concentration of polyphosphate is dependent on the analyte and in some cases, may be lower than the quantities previously used in routine detection. However, the concentration of polyphosphate should not be lowered in permanganate reagents that have been partially reduced to form high concentrations of the key manganese(III) co-reactant, as this intermediate needs to be stabilised to prevent formation of insoluble manganese(IV).
Zwitterionic ion chromatography with carboxybetaine surfactant-coated particle packed and monolithic type columns
Publisher: Elsevier BV
Date: 04-2005
DOI: 10.1016/J.CHROMA.2005.02.062
Abstract: Both particle packed (25 cm x 0.46 cm I.D. SUPELCOSIL 5 microm C18) and monolithic type (10 cm x 0.46 cm I.D. Merck Chromolith Performance C18) reversed-phase substrates were dynamically coated with a carboxybetaine type zwitterionic surfactant ((dodecyldimethyl-amino) acetic acid) and investigated as stationary phases for use in zwitterionic ion chromatography (ZIC). Investigations into eluent concentration and pH were carried out using KCl eluents containing 0.2 mM of the carboxybetaine surfactant to stabilise the column coatings. It was found that eluent concentration decreased anion retention whilst simultaneously increasing peak efficiencies, which may be due to the dissociation of intra- and inter-molecular salts of the carboxybetaine surfactant under higher ionic strength conditions. The Effect of eluent pH was an increase in anion retention with decreased eluent pH due to the increased protonation of the weak acid terminal group of the carboxybetaine, causing both a relative increase in the positive charge of the stationary phase and less repulsion of the anions by the dissociated weak acid group. The carboxybetaine-coated monolithic phase was applied to rapid anion separations using elevated flow rates and flow rate gradients.
Normal-phase high-performance counter-current chromatography for the fractionation of dissolved organic matter from a freshwater source
Publisher: Wiley
Date: 12-12-2013
Abstract: Normal-phase high-performance counter-current chromatography (HPCCC) is used to obtain a preliminary fractionation of components in dissolved organic matter (DOM) from a freshwater source. The HPCCC solvent system involved a normal-phase approach with water/methanol (1:1) as the lower stationary phase and hexane/ethyl acetate (1:1) as the upper mobile phase. The critical experiment parameters were optimised: revolution speed 1800 rpm and flow rate 0.15 mL/min. Under these conditions 50 μL of a 0.50 mg/mL DOM solution was loaded. The detection wavelength was monitored at 330 nm in order to isolate the main portion of DOM, which includes substances such as carboxyl-rich alicyclic molecules. By optimising this system it was possible to isolate materials that, according to GC-MS, can be related to molecules with an analogous structural background. Where fraction analysis was not suitable for GC-MS, RP-HPLC with UV absorbance detection was used, showing unique chromatograms for each fraction at both 210 and 330 nm.
On‐column titration and investigation of metal complex formation for aminopolycarboxylate functionalised monoliths using scanning contactless conductivity detection
Publisher: Wiley
Date: 08-2009
Abstract: The application of scanning capacitively coupled contactless conductivity detection (SC 4 D) for the determination of pH dependant behaviour of two aminopolycarboxylates immobilised onto the surface of a monolithic capillary column is described. The use of SC 4 D to visualise changes in conductivity of the discrete zones of functional groups within monolithic capillary columns allows for the effects of immobilisation on the physicochemical properties of zones to be compared to that of the functional group in solution. The perturbation of the p K a values of the functional groups can be attributed to the change in chemical environment experienced by the functional group through the presence of local hydrogen bonding and surface induced effects. These bonds, both between adjacent functional groups and with the monolithic polymethacrylate scaffold, result in a modification of the electron density on the functional group and therefore a change in p K a . Changes in the p K a of N ‐(2‐acetamido)iminodiacetic acid (ADA) from 2.48 to 5.2 for one of the acidic protons, with little change in the p K a of the amine group, were observed, which correlates to similar changes in aggregated systems of aminopolycarboxylates. Similar results were obtained for the iminodiacetic acid (IDA) once immobilised onto the surface of the monolith. Furthermore, the ability to measure changes in the charge of such discrete zones of functional groups allows for the visualisation of complexation events occurring directly on‐column, where such complexes result in a change in charge of the functional group. This potentially useful technique is illustrated within for the formation of aminopolycarboxylate complexes with a selection of metal ions.
Kinetics and selectivity of permanganate chemiluminescence: A study of hydroxyl and amino disubstituted benzene positional isomers
Publisher: Elsevier BV
Date: 11-2011
DOI: 10.1016/J.ACA.2011.09.024
Abstract: Examination of the chemiluminescence reactions of dihydroxybenzenes, aminophenols and phenylenediamines with acidic potassium permanganate has provided a new understanding of the relationships between analyte structure, reaction conditions, kinetics of the light-producing pathway and emission intensity, with broad implications for this widely utilised chemiluminescence detection system. Using a permanganate reagent prepared in a polyphosphate solution and adjusted to pH 2.5, large differences in the rate of reaction with different positional isomers were observed, with the meta-substituted forms reacting far slower and therefore exhibiting much lower chemiluminescence intensities in flow analysis systems. The preliminary partial reduction of permanganate to form significant concentrations of Mn(III) increased the rate of reaction with all analytes tested, resulting in comparable or (in the case of aminophenol and phenylenediamine) even greater emission intensities for the meta-isomers, demonstrating the opportunity to tune the selectivity of the reagent towards certain classes of compound or even specific positional isomers of the same compound. Using more acidic permanganate reagents, in which polyphosphates are not required, the discrepancy between the chemiluminescence intensities was still observed, but was less prominent due to the generally faster rates of reaction. The enhancement of these chemiluminescence reactions by on-line addition of formic acid or formaldehyde can in part also be attributed to the generation of significant pools of the key Mn(III) precursor to the emitting species.
Determination of trace labile copper in environmental waters by magnetic nanoparticle solid phase extraction and high-performance chelation ion chromatography
Publisher: Elsevier BV
Date: 04-2015
DOI: 10.1016/J.TALANTA.2014.12.048
Abstract: Cobalt magnetic nanoparticles surface functionalised with iminodiacetic acid were evaluated as a nano-particulate solid phase extraction absorbent for copper ions (Cu(2+)) from environmental water s les. Using an external magnetic field, the collector nanoparticles could be separated from the aqueous phase, and adsorbed ions simply decomplexed using dilute HNO3. Effects of pH, buffer concentration, s le and sorbent volume, extraction equilibrium time, and interfering ion concentration on extraction efficiency were investigated. Optimal conditions were then applied to the extraction of Cu(2+) ions from natural water s les, prior to their quantitation using high-performance chelation ion chromatography. The limits of detection (LOD) of the combined extraction and chromatographic method were ~0.1 ng ml(-1), based upon a 100-fold preconcentration factor (chromatographic performance LOD=9.2 ng ml(-1) Cu(2+)), analytical linear range from 20 to 5000 ng mL(-1), and relative standard deviations=4.9% (c=1000 ng ml(-1), n=7). Accuracy and precision of the combined approach was verified using a certified reference standard estuarine water s le (SLEW-2) and comparison of s le determinations with sector field inductively coupled plasma mass spectrometry. Recoveries from the addition of Cu(2+) to impacted estuarine and rain water s les were 103.5% and 108.5%, respectively. Coastal seawater s les, both with and without prior UV irradiation and dissolved organic matter removal were also investigated using the new methodology. The effect of DOM concentration on copper availability was demonstrated.
Investigation into dissolved neutral sugars and their microbial conversion in natural and artificially produced dissolved organic matter using ion chromatography with pulsed amperometric detection and reversed-phase liquid chromatography-high resolution mass spectrometry
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3AY41549J
Low pressure ion chromatography with a low cost paired emitter–detector diode based detector for the determination of alkaline earth metals in water samples
Publisher: Elsevier BV
Date: 09-2006
DOI: 10.1016/J.ACA.2006.05.101
Abstract: The use of a low pressure ion chromatograph based upon short (25 mm x 4.6 mm) surfactant coated monolithic columns and a low cost paired emitter-detector diode (PEDD) based detector, for the determination of alkaline earth metals in aqueous matrices is presented. The system was applied to the separation of magnesium, calcium, strontium and barium in less than 7min using a 0.15M KCl mobile phase at pH 3, with post-column reaction detection at 570 nm using o-cresolphthalein complexone. A comparison of the performance of the PEDD detector with a standard laboratory absorbance detector is shown, with limits of detection for magnesium and calcium using the low cost PEDD detector equal to 0.16 and 0.23 mg L(-1), respectively. Finally, the developed system was used for the determination of calcium and magnesium in a commercial spring water s le.
Hierarchical porous graphitic carbon monoliths with detonation nanodiamonds: synthesis, characterisation and adsorptive properties
Publisher: Springer Science and Business Media LLC
Date: 24-06-2015
Capillary gap flow cell as capillary-end electrochemical detector in flow-based analysis
Publisher: Elsevier BV
Date: 04-2019
Simple, quantitative method for low molecular weight dissolved organic matter extracted from natural waters based upon high performance counter-current chromatography
Publisher: Elsevier BV
Date: 02-2016
DOI: 10.1016/J.ACA.2016.01.003
Abstract: A simple, high-performance counter-current chromatography method with sequential UV absorbance (254 nm) and evaporative light scattering detection (ELSD) was developed for the quantification of pre-extracted low molecular weight dissolved organic matter (DOM) extracted from natural waters. The method requires solid-phase extraction (SPE) extraction of only small volumes of water s les, here using poly(styrene inylbenzene)-based extraction cartridges (Varian PPL). The extracted and concentrated DOM was quantified using reversed-phase high-performance counter-current chromatography (HPCCC), with a water/methanol (5:5) mobile phase and hexane/ethyl acetate (3:7) stationary phase. The critical chromatographic parameters were optimised, applying a revolution speed of 1900 rpm and a flow-rate of 1 mL min(-1). Under these conditions, 50 μL of extracted DOM solution could be injected and quantified using calibration against a reference natural dissolved material (Suwannee River), based upon UV absorbance at 254 nm and ELSD detection. Both detection methods provided excellent linearity (R(2) > 0.995) for DOM across the concentration ranges of interest, with limits of detection of 4 μg ml(-1) and 7 μg ml(-1) for ELSD and UV absorbance, respectively. The method was validated for peak area precision ( 95% recovery). The developed method was applied to the determination of the concentration of DOM in seawater, based upon initial s le volumes as small as 20 mL.
Single column comprehensive analysis of pharmaceutical preparations using dual-injection mixed-mode (ion-exchange and reversed-phase) and hydrophilic interaction liquid chromatography
Publisher: Elsevier BV
Date: 12-2013
DOI: 10.1016/J.JPBA.2013.08.003
Abstract: The comprehensive separation and detection of hydrophobic and hydrophilic active pharmaceutical ingredients (APIs), their counter-ions (organic, inorganic) and excipients, using a single mixed-mode chromatographic column, and a dual injection approach is presented. Using a mixed-mode Thermo Fisher Acclaim Trinity P1 column, APIs, their counter-ions and possible degradants were first separated using a combination of anion-exchange, cation-exchange and hydrophobic interactions, using a mobile phase consisting of a dual organic modifier/salt concentration gradient. A complementary method was also developed using the same column for the separation of hydrophilic bulk excipients, using hydrophilic interaction liquid chromatography (HILIC) under high organic solvent mobile phase conditions. These two methods were then combined within a single gradient run using dual s le injection, with the first injection at the start of the applied gradient (mixed-mode retention of solutes), followed by a second s le injection at the end of the gradient (HILIC retention of solutes). Detection using both ultraviolet absorbance and refractive index enabled the sensitive detection of APIs and UV-absorbing counter-ions, together with quantitative determination of bulk excipients. The developed approach was applied successfully to the analysis of a dry powder inhalers (Flixotide(®), Spiriva(®)), enabling comprehensive quantification of all APIs and excipients in the s le.
A 3D printable diamond polymer composite: a novel material for fabrication of low cost thermally conducting devices
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6RA05261D
Abstract: A low cost 3D stereolithography based printer has been used for a new polymer composite material with enhanced thermal properties containing 30 wt% micro-particulate diamond.
Capillary electrophoresis for the analysis of paralytic shellfish poisoning toxins in shellfish: Comparison of detection methods
Publisher: Wiley
Date: 13-04-2014
Abstract: Paralytic shellfish toxins (PSTs) are produced by marine and freshwater microalgae and accumulate in shellfish including mussels, oysters, and scallops, causing possible fatalities when inadvertently consumed. Monitoring of PST content of shellfish is therefore important for food safety, with currently approved methods based on HPLC, using pre- or postcolumn oxidation for fluorescence detection (HPLC-FLD). CE is an attractive alternative for screening and detection of PSTs as it is compatible with miniaturization and could be implemented in portable instrumentation for on-site monitoring. In this study, CE methods were developed for C(4) D, FLD, UV absorption detection, and MS-making this first report of C(4) D and FLD for PSTs detection. Because most oxidized toxins are neutral, MEKC was used in combination with FLD. The developed CZE-UV and CZE-C(4) D methods provide better resolution, selectivity, and separation efficiency compared to CZE-MS and MEKC-FLD. The sensitivity of the CZE-C(4) D and MEKC-FLD methods was superior to UV and MS, with LOD values ranging from 140 to 715 ng/mL for CZE-C(4) D and 60.9 to 104 ng/mL for MEKC-FLD. With the regulatory limit for shellfish s les of 800 ng/mL, the CZE-C(4) D and MEKC-FLD methods were evaluated for the screening and detection of PSTs in shellfish s les. While the CZE-C(4) D method suffered from significant interferences from the shellfish matrix, MEKC-FLD was successfully used for PST screening of a periodate-oxidized mussel s le, with results confirmed by HPLC-FLD. This confirms the potential of MEKC-FLD for screening of PSTs in shellfish s les.
Fractionation of Dissolved Organic Matter on Coupled Reversed-Phase Monolithic Columns and Characterisation Using Reversed-Phase Liquid Chromatography-High Resolution Mass Spectrometry
Publisher: Springer Science and Business Media LLC
Date: 25-05-2018
A new 3D printed radial flow-cell for chemiluminescence detection: Application in ion chromatographic determination of hydrogen peroxide in urine and coffee extracts
Publisher: Elsevier BV
Date: 04-2018
DOI: 10.1016/J.ACA.2017.12.039
Abstract: A new polymer flow-cell for chemiluminescence detection (CLD) has been designed and developed by erging multiple linear channels from a common centre port in a radial arrangement. The fabrication of radial flow-cell by 3D PolyJet printing and fused deposition modeling (FDM) has been evaluated, and compared with a similarly prepared spiral flow-cell design commonly used in chemiluminescence detectors. The radial flow-cell required only 10 h of post-PolyJet print processing time as compared to ca. 360 h long post-PolyJet print processing time required for the spiral flow-cell. Using flow injection analysis, the PolyJet 3D printed radial flow-cell provided an increase in both the signal magnitude and duration, with an average increase in the peak height of 63% and 58%, peak area of 89% and 90%, and peak base width of 41% and 42%, as compared to a coiled-tubing spiral flow-cell and the PolyJet 3D printed spiral flow-cell, respectively. Computational fluid dynamic (CFD) simulations were applied to understand the origin of the higher CLD signal obtained with the radial flow-cell design, indicating higher spatial coverage near the inlet and lower linear velocities in the radial flow-cell. The developed PolyJet 3D printed radial flow-cell was applied in a new ion chromatography chemiluminescence based assay for the detection of H
Use of contactless conductivity detection for non-invasive characterisation of monolithic stationary-phase coatings for application in capillary ion chromatography
Publisher: Royal Society of Chemistry (RSC)
Date: 2007
DOI: 10.1039/B711350A
Abstract: A capacitively-coupled contactless conductivity detector (C4D) has been utilised as an on-capillary detector within a capillary ion chromatograph, incorporating a reversed-phase monolithic silica capillary column semi-permanently modified with a suitable ionic surfactant. The monolithic capillary column (150 x 0.1 mm i.d.) was modified using sodium dioctyl sulfosuccinate (DOSS), an anionic surfactant, for the separation of small inorganic and organic cations. With the use of the on-capillary conductivity detector, the longitudinal homogeneity and temporal stability of the coating were investigated. The approach allowed a detailed non-invasive observation of the nature of the ion-exchange coating over time, and an ex le of an application of the technique to produce a longitudinal stationary-phase charge gradient is shown. An investigation of the basis of the measured on-capillary conductivity was carried out with a counter ion study, clearly showing the on-capillary detection technique could also distinguish between chemical forms of the immobilised ion exchanger. The above method was used to produce a stable and homogeneously-modified monolithic ion-exchange capillary column, for application to the separation of inorganic alkaline earth cations and amino acids.
Solvent enhanced ion chromatography of alkaline earth and transition metal ions on porous monolithic silica
Publisher: Elsevier BV
Date: 11-2005
Separation of uranium(VI) and lanthanides by capillary electrophoresis using on-capillary complexation with arsenazo III
Publisher: Elsevier BV
Date: 04-1998
Evaluation of a miniaturised single-stage thermal modulator for comprehensive two-dimensional gas chromatography of petroleum contaminated soils
Publisher: Elsevier BV
Date: 09-2016
DOI: 10.1016/J.CHROMA.2016.08.009
Abstract: A novel miniaturised single-stage resistively heated thermal modulator was investigated as an alternative to cryogenic modulation for use in comprehensive two-dimensional gas chromatography (GC×GC). The single-stage thermal modulator described herein yielded average retention time relative standard deviations (RSD) of ≤0.2% RSD (first-dimension) and ≤3.4% RSD (second-dimension). The average peak widths generated by the modulator were 72±3ms, and the peak area precision was better than 5.3% RSD for a range of polar and non-polar test analytes. GC×GC analysis can be performed using this modulator without the requirement for cryogenic cooling or additional pressure control modules for flow modulation. The modulator and associated electronics are compact and amenable towards field analysis. The modulator was used for qualitative and quantitative characterisation of petroleum-contaminated soils derived from a sub-Antarctic research station at Macquarie Island. The limit of detection compared to standard 1D GC analysis was improved from 64 to 11mgkg(-1). An automated method of analysing and categorising s les using principal component analysis is presented.
Determination of trace magnesium and strontium in calcium carbonate and calcareous skeletons of marine planktonic organisms using high performance chelation ion chromatography
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4AY02126F
Abstract: A new high performance chelation ion chromatography method for the simultaneous determination of trace magnesium and strontium in various calcium carbonate s les was developed.
Capillary ion chromatography of inorganic anions on octadecyl silica monolith modified with an amphoteric surfactant
Publisher: Elsevier BV
Date: 02-2007
DOI: 10.1016/J.CHROMA.2006.12.049
Abstract: A reversed-phase monolithic silica based capillary column (Onyx C(18), 150 mm x 0.1 mm) was modified with the hoteric surfactant, N-dodecyl-N,N-(dimethylammonio)undecanoate (DDMAU) and evaluated for the separation and determination of inorganic anions using on-column capacitively coupled contactless conductivity detection (C(4)D). The chromatographic performance of the column was evaluated and under optimal conditions separation efficiencies of 56,200 plates per meter or 7025 plates per column (at detection point) were observed (for iodide). Direct plumbing of the capillary column to the micro-injector and on-column detection eliminated extra-column band broadening, thus allowing accurate analysis of van Deemter curves obtained for the monolithic capillary column. The calculated value for the C-term in the obtained van Deemter curve was between 3 and 4 ms for inorganic anions, allowing for the utilisation of relatively high flow rates without significant losses in efficiency. The performance of the C(4)D detector was investigated and compared for detection on an open tubular capillary column and on the modified monolithic silica capillary column. The on-column detection approach did not result in any significant decrease in peak sensitivity for the monolith compared to responses recorded for open tubular capillary columns, and in addition meant the system could be applied to rapid separations by simple variation in apparent column length. The proposed chromatographic system allowed for detection of common anions at sub-ppm level with a 10 nL injection volume. Additionally, on-column detection allowed visualisation of the development of the separation at any point in time and evaluation of the longitudinal uniformity of the ion-exchange coating.
Ion-exchange and hydrophobic interactions affecting selectivity for neutral and charged solutes on three structurally similar agglomerated ion-exchange and mixed-mode stationary phases
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.ACA.2013.03.063
Abstract: The nature and extent of mixed-mode retention mechanisms evident for three structurally related, agglomerated, particle-based stationary phases were evaluated. These three agglomerated phases were Thermo Fisher ScientificIon PacAS11-HC - strong anion exchange, Thermo Fisher Scientific IonPac CS10--strong cation-exchange PS-DVB, and the Thermo Fisher Scientific Acclaim Trinity P1silica-based substrate, which is commercially marketed as a mixed-mode stationary phase. All studied phases can exhibit zwitterionic and hydrophobic properties, which contribute to the retention of charged organic analytes. A systematic approach was devised to investigate the relative ion-exchange capacities and hydrophobicities for each of the three phases, together with the effect of eluent pH upon selectivity, using a specifically selected range of anionic, cationic and neutral aromatic compounds. Investigation of the strong anion-exchange column and the Trinity P1 mixed-mode substrate, in relation to ion-exchange capacity and pH effects, demonstrated similar retention behaviour for both the anionic and holytic solutes, as expected from the structurally related phases. Further evaluation revealed that the ion-exchange selectivity of the mixed-mode phase exhibited properties similar to that of the strong anion-exchange column, with secondary cation-exchange selectivity, albeit with medium to high anion-exchange and cation-exchange capacities, allowing selective retention for each of the anionic, cationic and holytic solutes. Observed mixed-mode retention upon the examined phases was found to be a sum of anion- and cation-exchange interactions, secondary ion-exchange and hydrophobic interactions, with possible additional hydrogen bonding. Hydrophobic evaluation of the three phases revealed logP values of 0.38-0.48, suggesting low to medium hydrophobicity. These stationary phases were also benchmarked against traditional reversed-phase substrates namely, octadecylsilica YMC-Pac Pro C18 and neutral μPS-DVB resin IonPac NS1-5u, yielding logP values of 0.57 and 0.52, respectively.
Application of capillary ion chromatography and capillary ion chromatography coupled with mass spectrometry to determine methanesulfonate and inorganic anions in microliter sample volumes of Antarctic
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6AY02426B
Abstract: Development of low volume capillary ion chromatography to deliver anion records from Antarctic snow pit s les.
Prospects of pulsed amperometric detection in flow-based analytical systems - A review
Publisher: Elsevier BV
Date: 04-2019
DOI: 10.1016/J.ACA.2018.10.066
Abstract: Electrochemical (EC) detection techniques in flow-based analytical systems such as flow injection analysis (FIA), capillary electrophoresis (CE), and liquid chromatography (LC) have attracted continuous interest over the last three decades, leading to significant advances in EC detection of a wide range of analytes in the liquid phase. In this context, the unique advantages of pulsed erometric detection (PAD) in terms of high sensitivity and selectivity, and electrode cleaning through the application of pulsed potential for noble metal electrodes (e.g. Au, Pt), have established PAD as an important detection technique for a variety of electrochemically active compounds. PAD is especially valuable for analytes not detectable by ultraviolet (UV) photometric detection, such as organic aliphatic compounds and carbohydrates, especially when used with miniaturised capillary and chip-based separation methods. These applications have been accomplished through advances in PAD potential waveform design, as well as through the incorporation of nanomaterials (NMs) employed as microelectrodes in PAD. PAD allows on-line pulsed potential cleaning and coupling with capillary or standard separation techniques. The NMs are largely employed in microelectrodes to speed up mass and electron transfer between electrode surfaces and to perform as reactants in EC analysis. These advances in PAD have improved the sensitive and selective EC detection of analytes, especially in biological s les with complex s le matrices, and detection of electro-inactive compounds such as aliphatic organic compounds (i.e., formic acid, acetic acid, maleic acids, and β-cyclodextrin complexes). This review addresses the fundamentals of PAD, the role of pulsed sequences in AD, the utilisation of different EC detectors for PAD, technological advancements in PAD waveforms, utilisation of microelectrodes in PAD techniques, advances in the use of NMs in PAD, the applications of PAD, and prospects for EC detection, with emphasis on PAD in flow-based systems.
Double gradient ion chromatography on a short carboxybetaine coated monolithic anion exchanger
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B414323J
Abstract: An ultra-short 1.0 x 0.46 cm carboxybetaine coated monolithic anion exchanger has been used with a new double gradient ion chromatography (DG-IC) technique. The novel monolithic column can be used with flow rate gradients giving excellent peak efficiencies, and retention times can be simultaneously reduced through combining flow gradients with an eluent pH gradient.
Separation of superparamagnetic magnetite nanoparticles by capillary zone electrophoresis using non-complexing and complexing electrolyte anions and tetramethylammonium as dispersing additive
Publisher: Wiley
Date: 25-04-2018
Abstract: Separations of bare superparamagnetic magnetite nanoparticles (BSPMNPs, approx. 11 nm diameter) was performed using non-complexing (nitrate) and complexing (chloride, citrate and phosphate) electrolyte ions with additions of tetramethylammonium hydroxide (TMAOH), which is commonly applied to control the synthesis of stable iron oxides. The use of TMAOH as a background electrolyte (BGE) additive for capillary electrophoresis (CE) separations provided for the first time electropherograms of BSPMNPs exhibiting symmetrical and highly reproducible peaks, free of spurious spikes characteristic of nanoparticle clusters. Consequently, accurate determination of the electrophoretic effective mobility of BSPMNPs was possible, yielding a value of -3.345E-08 m
Fast ion chromatography of inorganic anions and cations on a lysine bonded porous silica monolith
Publisher: Elsevier BV
Date: 05-2005
DOI: 10.1016/J.CHROMA.2005.03.126
Abstract: A 0.46 cm x 10.0 cm silica monolith column was modified through the in situ covalent attachment of lysine (2,6-diaminohexanoic acid) groups. Due to the zwitterionic nature of the resultant stationary phase, the modified monolithic column contained both cation and anion exchange capacity. In the case of cation exchange, the capacity was found to be relatively low at between 5 and 6.5 micromoles Me2+ per column. However, as expected, the lysine monolith exhibited a higher anion exchange capacity at 12-13 micromoles A- per column (at pH 3.0), which was found to be dependent upon column pH, due to the dissociation of the weak acid carboxylic acid groups. High-performance separations of transition metal cations and inorganic anions were achieved using the modified monolith, with the effects of eluent concentration, pH and flow rate evaluated. Using elevated flow rates of up to 5 mL/min the separation of nitrite, bromate, bromide, nitrate, iodide and thiocyanate was possible in approximately 100 s with peak efficiencies of between 50 and 100,000 N/m and retention time %RSD of under 0.3%.
High-throughput deposition of chemical reagents via pen-plotting technique for microfluidic paper-based analytical devices
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.ACA.2018.09.006
Abstract: The deposition of chemical reagent inks on paper is a crucial step in the development and fabrication of microfluidic paper-based analytical devices (μPADs). A pen-plotting approach, delivering chemical ink deposition using technical pens filled with reagents and inserted into a desktop electronic plotter, is shown herein to be a versatile, low-cost, simple, rapid, reproducible, and high-throughput solution. The volume of the deposited ink was quantified gravimetrically, confirming that nanoliter volumes of reagents can be deposited reproducibly (e.g. 7.55 ± 0.37 nL/mm for a plotting speed of 10 cm/s) in detection zones of μPADs, typically spatially defined using wax printing. This approach was further investigated with regard to deposition of reagents in different geometrical forms (circular and linear), so demonstrating its applicability for preparation of μPADs with flexible design and application. By adjusting the plotting speed for linear deposition, lines with a relatively large range of widths (≈628-1192 μm) were created. Circular deposition was also demonstrated via delivery of reagents within wax printed circular fluidic barriers of a range of diameters (inner diameter = 1.5-7 mm). These capabilities were practically demonstrated via the fabrication of μPADs, based upon differing detection principles for determination of aluminum in natural waters using Morin as the fluorescent reagent. Traditional μPADs based on digital image colorimetry (DIC) were produced using circular deposition, whilst distance-based μPADs exploited linear deposition. Both types of μPADs developed using this method showed excellent precision for determination of trace concentrations of aluminium (average RSDs = 3.38% and 6.45%, and LODs = 0.5 ng (0.25 ppm) and 2 ng (0.5 ppm), for traditional and distance-based detection, respectively).
Recent developments in 3D printable composite materials
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6RA11334F
Abstract: The formulation of new composite materials compatible with additive fabrication techniques is driving a revolution in the field of applied materials science.
A simple and sensitive method for the determination of iodide and iodate in raw, ultraviolet- and ozone-treated aquacultural seawater samples using ion chromatography coupled to an ultraviolet detecto
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6AY01381C
Abstract: A new and sensitive ion chromatographic method for the speciation of iodine in aquacultural seawater s les has been developed.
Significant viscosity dependent deviations from classical van Deemter theory in liquid chromatography with porous silica monolithic columns
Publisher: Royal Society of Chemistry (RSC)
Date: 2005
DOI: 10.1039/B502514A
Abstract: Significant deviations from classical van Deemter behaviour, indicative of turbulent flow liquid chromatography, has been recorded for mobile phases of varying viscosity on porous silica monolithic columns at elevated mobile phase flow rates.
Back-flushing and heart cut capillary gas chromatography using planar microfluidic Deans’ switching for the separation of benzene and alkylbenzenes in industrial samples
Publisher: Elsevier BV
Date: 11-2015
DOI: 10.1016/J.CHROMA.2015.10.027
Abstract: Planar microfluidic devices coupled with modern electronic pressure control have allowed gas chromatography (GC) practitioners to easily manipulate chromatographic systems to achieve heart cut and back-flushing configurations. These planar microfluidic devices have enhanced the connectivity between different components of GC instrumentation and have improved the inertness and minimised system dead volumes compared to classical chromatographic unions and valves. In the present contribution the setup and configuration of two multidimensional GC (MDGC) platforms is described for achieving the separation and quantification of trace level target C6-C8 alkylbenzenes in styrene monomer and Isoparaffin™ solvents, using flame ionisation detection (FID). The performance of these MDGC platforms indicated excellent retention time (0.2% relative standard deviation, RSD) and peak area repeatability (1% RSD) for all analytes of interest. The limit of detection (LOD) was 0.8 mg kg(-1) for benzene in styrene monomer, and 2.4-2.8 mg kg(-1) for C6-C8 alkylbenzenes such as benzene, toluene, ethylbenzene and xylene in Isoparaffin™ solvent.
Iminodiacetic acid functionalised monolithic silica chelating ion exchanger for rapid determination of alkaline earth metal ions in high ionic strength samples
Publisher: Royal Society of Chemistry (RSC)
Date: 17-04-2003
DOI: 10.1039/B303467D
Abstract: Iminodiacetic acid has been covalently bonded to a bare silica monolith to produce the first reported high-performance monolithic chelating ion exchange column. Using the new column, separation and determination of traces of alkaline earth metal ions (low ppm) in high ionic strength s les (up to 2 M NaCl and KCl brines), could be achieved in under 40 s. At an eluent flow rate of 4 mL min(-1) retention time precision was < 1.2% (n = 9) for Mg(II) and Ca(II), with detector linearity (n = 5) over the range 2-10 mg L(-1) of between R2 = 0.985 and R2 = 0.995. In 1 M KCl and NaCl brine s les, detection limits of 0.2 mg L(-1) were possible.
Adsorption and Desorption of Methylene Blue on Porous Carbon Monoliths and Nanocrystalline Cellulose
Publisher: American Chemical Society (ACS)
Date: 22-08-2013
DOI: 10.1021/AM403222U
Abstract: The dynamic batch adsorption of methylene blue (MB), a widely used and toxic dye, onto nanocrystalline cellulose (NCC) and crushed powder of carbon monolith (CM) was investigated using the pseudo-first- and -second-order kinetics. CM outperformed NCC with a maximum capacity of 127 mg/g compared to 101 mg/g for NCC. The Langmuir isotherm model was applicable for describing the binding data for MB on CM and NCC, indicating the homogeneous surface of these two materials. The Gibbs free energy of -15.22 kJ/mol estimated for CM unravelled the spontaneous nature of this adsorbent for MB, appreciably faster than the use of NCC (-4.47 kJ/mol). Both pH and temperature exhibited only a modest effect on the adsorption of MB onto CM. The desorption of MB from CM using acetonitrile was very effective with more than 94 % of MB desorbed from CM within 10 min to allow the reusability of this porous carbon material. In contrast, acetonitrile was less effective than ethanol in desorbing MB from NCC. The two solvents were incapable of completely desorbing MB on commercial granular coal-derived activated carbon.
UiO-66@SiO2 core–shell microparticles as stationary phases for the separation of small organic molecules
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6AN02344D
Abstract: Microparticles decorated with metal–organic frameworks exhibited a unique flow-dependent separation selectivity (FDSS) effect for the isocratic separation of small molecules.
Flow injection analysis of organic peroxide explosives using acid degradation and chemiluminescent detection of released hydrogen peroxide
Publisher: Elsevier BV
Date: 10-2015
DOI: 10.1016/J.TALANTA.2015.05.052
Abstract: The applicability of acid degradation of organic peroxides into hydrogen peroxide in a pneumatically driven flow injection system with chemiluminescence reaction with luminol and Cu(2+) as a catalyst (FIA-CL) was investigated for the fast and sensitive detection of organic peroxide explosives (OPEs). The target OPEs included hexamethylene triperoxide diamine (HMTD), triacetone triperoxide (TATP) and methylethyl ketone peroxide (MEKP). Under optimised conditions maximum degradations of 70% and 54% for TATP and HMTD, respectively were achieved at 162 µL min(-1), and 9% degradation for MEKP at 180 µL min(-1). Flow rates were precisely controlled in this single source pneumatic pressure driven multi-channel FIA system by model experiments on mixing of easily detectable component solutions. The linear range for detection of TATP, HMTD and H2O2 was 1-200 µM (r(2)=0.98-0.99) at both flow rates, while that for MEKP was 20-200 µM (r(2)=0.97) at 180 µL min(-1). The detection limits (LODs) obtained were 0.5 µM for TATP, HMTD and H2O2 and 10 µM for MEKP. The detection times varied from 1.5 to 3 min in this FIA-CL system. Whilst the LOD for H2O2 was comparable with those reported by other investigators, the LODs and analysis times for TATP and HMTD were superior, and significantly, this is the first time the detection of MEKP has been reported by FIA-CL.
Dual gradient LC method for the determination of pharmaceutical residues in environmental samples using a monolithic silica reversed phase column
Publisher: Informa UK Limited
Date: 15-06-2006
Poly(tetrafluoroethylene) separation capillaries for capillary electrophoresis
Publisher: Elsevier BV
Date: 06-2004
DOI: 10.1016/J.CHROMA.2004.03.074
Abstract: Poly(tetrafluoroethylene) (PTFE) is a material widely known for its inertness and excellent electrical properties. It is also transparent in the UV region and has a reasonable thermal conductivity. These properties make PTFE a suitable material for the separation capillary in capillary electrophoresis. Differences in the chemistry of the capillary wall compared to fused silica (FS) can make PTFE an interesting alternative to FS for some special applications. In this work, properties of a commercial PTFE capillary of approx. 100 microm i.d. were investigated, including the dependence of electroosmotic flow (EOF) on pH for unmodified and dynamically modified PTFE, optical properties, and practical aspects of use. The main problems encountered for the particular PTFE capillary used in this study were that it was mechanically too soft for routine usage and the crystallinity of the PTFE caused light scattering, leading to high background absorbance values in the low UV region. The profile of the EOF versus pH for bare PTFE surprisingly showed significantly negative EOF values at pH < 4.2, with an EOF of -30 x 10(-9) m2 V(-1) s(-1) being observed at pH 2.5. This is likely to be caused by either impurities or additives of basic character in the PTFE, so that after their protonation at acidic pH they establish a positive charge on the capillary wall and create a negative EOF. A stable cationic semi-permanent coating of poly(diallyldimethylammonium chloride) (PDDAC) could be established on the PTFE capillary and led to very similar magnitudes of EOF to those observed with FS. A hexadecanesulfonate coating produced a cathodic EOF of extremely high magnitude ranging between +90 and +110 x 10(-9) m2 s(-1) V(-1), which are values high enough to allow counter-EOF separation of high mobility inorganic anions. In addition, pH-independent micellar electrokinetic capillary chromatography (MEKC) separations could be easily realised due to hydrophobic adsorption of sodium dodecylsulfate (used to form the micelles) on the wall of the PTFE capillary. The use of polymers that would be mechanically more robust and optically transparent in the low-UV region should make such CE capillaries an interesting alternative to fused silica.
Chromatographic properties of hydrogenated microdiamond synthesized by high pressure and high temperature
Publisher: Elsevier BV
Date: 06-2022
DOI: 10.1016/J.CHROMA.2022.463127
Abstract: Adsorption and chromatographic properties of oxidized and hydrogenated 'high pressure and high temperature' synthesised diamond (HPHT) are studied using high-performance liquid chromatography. The retention factors of organic cation (benzyltributylammonium chloride), weak base (aniline), weak acid (benzoic acid), strong acid (benzenesulfonic acid), hydrophobic toluene, and hydrophilic uracil are obtained at varied pH, organic solvent content, and ionic strength of mobile phase. Both adsorbents exhibited moderate polarity with a mixed-mode retention mechanism with a combination of electrostatic, hydrophobic and hydrophilic interactions. Unexpectedly, hydrogenated HPHT revealed significant anion-exchange properties under acidic conditions and cation-exchange properties under alkaline conditions, while only cation-exchange selectivity was noted for oxidized HPHT across the enntire pH range. The retention factors obtained for a set of model compounds including n-alkyl-, polymethyl-, nitro- and halogenated benzenes correlated well with their hydrophobicity (logP) values. The thermal stability of the adsorbent and immutability of retention mechanisms involved was confirmed by linear van't Hoff plots for the investigated compounds.
Fast and sensitive determination of aluminium with RP-HPLC using an ultra-short monolithic column
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1AY05192J
Ultra-Fast Continuous-Flow Photo Degradation of Organic Peroxide Explosives for Their Efficient Conversion into Hydrogen Peroxide and Possible Application
Publisher: Wiley
Date: 26-01-2016
Screening of elemental impurities in commercial detonation nanodiamond using sector field inductively coupled plasma-mass spectrometry
Publisher: Springer Science and Business Media LLC
Date: 30-01-2014
Low-Cost Passive Sampling Device with Integrated Porous Membrane Produced Using Multimaterial 3D Printing
Publisher: American Chemical Society (ACS)
Date: 17-09-2018
DOI: 10.1021/ACS.ANALCHEM.8B02893
Abstract: Multimaterial 3D printing facilitates the rapid production of complex devices with integrated materials of varying properties and functionality. Herein, multimaterial fused deposition modeling (MM-FDM) 3D printing was applied to the fabrication of low-cost passive s ler devices with integrated porous membranes. Using MM-FDM 3D printing, the device body was produced using black polylactic acid, with Poro-Lay Lay-Felt filament used for the printing of the integrated porous membranes (rubber-elastomeric polymer, porous after removal of a water-soluble poly(vinyl alcohol) component). The resulting device consisted of two interlocking circular frames, each containing the integrated membrane, which could be efficiently sealed together without the need for additional O-rings, and prevented loss of enclosed microparticulate sorbent. Scanning electron microscopy (SEM) analysis of the purified composite filament confirmed the porous properties of the material, an average pore size of ∼30 nm. The printed passive s lers with various membrane thicknesses, including 0.5, 1.0, and 1.5 mm, were evaluated for their ability to facilitate the extraction of atrazine as the model solute onto the internal sorbent, under standard conditions. Gas chromatography-mass spectrometry was used to determine the uptake of atrazine by the device from standard water s les and also to evaluate any chemical leaching from the printed materials. The s ler with 0.5 mm thick membrane showed the best performance with 87% depletion and a s ling rate of 0.19 Ld
Non-invasive characterization of stationary phases in capillary flow systems using scanning capacitively coupled contactless conductivity detection (sC4D)
Publisher: Elsevier BV
Date: 09-2010
Miniaturised medium pressure capillary liquid chromatography system with flexible open platform design using off-the-shelf microfluidic components
Publisher: Elsevier BV
Date: 10-2015
DOI: 10.1016/J.ACA.2015.09.015
Abstract: Trends towards portable analytical instrumentation of the last decades have not been equally reflected in developments of portable liquid chromatography (LC) instrumentation for rapid on-site measurements. A miniaturised medium pressure capillary LC (MPLC) system with gradient elution capability has been designed based on a flexible modular microfluidic system using primarily off-the-shelf low cost components to ensure wide accessibility to other analysts. The microfluidic platform was assembled on a breadboard and contained microsyringe pumps and switch valves, complemented with an injection valve and on-capillary detectors, all controlled by a PC. Four miniaturised microsyringe pumps, with 5, 20 and 100 μL syringe volume options, formed the basis of the pumping system. Two pairs of pumps were used for each mobile phase to create gradient elution capability. The two microsyringe pumps in each pairs were linked by two electrically operated microfluidic switching valves and both pairs of pumps were connected through a zero void volume cross-connector, thus providing a low hold-up volume for gradient formation. S le was injected by a 20 nL nano-LC s ling valve, directly connected to a 18 cm long 100 μm i.d. Chromolith CapRod RP-18 monolithic capillary column. On-capillary LED-based UV-vis photometric detection was conducted through a piece of equal diameter fused silica capillary connected after the column. The performance of the portable LC system was evaluated theoretically and experimentally, including the maximum operating pressure, gradient mixing performance, and the performance of the detectors. The 5 μL microsyringe pump offered the best performance, with typical maximum operating pressures up to 11.4 ± 0.4 MPa (water) and gradient pumping repeatability of between 4 and 9% for gradients between 0.10% s(-1) and 0.33% s(-1). Test analytes of charged and uncharged dyes and pharmaceuticals of varying hydrophobicity showed typical RSD values of 0.7-1.4% and 3.3-4.8% in isocratic mode and 1.2-4.6% and 3.2-6.4% in gradient mode, respectively for retention time and peak area repeatability.
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