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0000-0003-1373-7493
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University of Natural Resources and Life Sciences
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Publisher: The Royal Society of Chemistry
Date: 21-07-2021
DOI: 10.1039/9781839163524-00165
Abstract: Applications of ion mobility (IM) coupled to high-resolution mass spectrometry, i.e., quadrupole time-of-flight (QTOF) instruments, have experienced a significant growth in recent years, especially in the ‘omics fields including metabolomics. Several types of instrumental platforms are now commercially available and exploit different operation principles for the IM separation. In this contribution, we discuss the current state of commercial IM–QTOFMS technology and data acquisition strategies relevant to metabolomics studies. Particular focus is placed on the strengths and weaknesses of the application of this technology both for data generation and emerging strategies and opportunities within data processing workflows that take full advantage of the added IM dimension.
Publisher: Elsevier BV
Date: 06-2021
Publisher: Wiley
Date: 08-12-2020
Publisher: Elsevier BV
Date: 04-2019
DOI: 10.1016/J.ACA.2018.11.040
Abstract: The characterization of wine via MS-based metabolic fingerprinting techniques remains a challenging undertaking due to the large number of phenolic compounds that cannot be confidently annotated and identified within analytical workflows. The combination of high performance liquid chromatography with low-field drift tube ion mobility time-of-flight mass spectrometry (HPLC × IMS-TOFMS) offers potential for the confident characterization and fingerprinting of wine using a metabolomics-type workflow. In particular, the use of collision cross section values from low-field drift tube IMS using nitrogen as drift gas (
Publisher: Future Science Ltd
Date: 2017
Abstract: Measuring the exposome remains a challenge due to the range and number of anthropogenic molecules that are encountered in our daily lives, as well as the complex systemic responses to these exposures. One option for improving the coverage, dynamic range and throughput of measurements is to incorporate ion mobility spectrometry (IMS) into current MS-based analytical methods. The implementation of IMS in exposomics studies will lead to more frequent observations of previously undetected chemicals and metabolites. LC-IMS-MS will provide increased overall measurement dynamic range, resulting in detections of lower abundance molecules. Alternatively, the throughput of IMS-MS alone will provide the opportunity to analyze many thousands of longitudinal s les over lifetimes of exposure, capturing evidence of transitory accumulations of chemicals or metabolites. The volume of data corresponding to these new chemical observations will almost certainly outpace the generation of reference data to enable their confident identification. In this perspective, we briefly review the state-of-the-art in measuring the exposome, and discuss the potential use for IMS-MS and the physico-chemical property of collisional cross section in both exposure assessment and molecular identification.
Publisher: Springer Science and Business Media LLC
Date: 26-04-2022
DOI: 10.1007/S11356-022-20301-2
Abstract: A fully non-targeted analytical workflow for the investigation of a riverbank filtration site located at the river Danube has been developed and applied. Variations of compound intensities at different s ling locations of the riverbank filtration site and, for a single production well, over a monitoring period of one year have been investigated using liquid chromatography combined with time-of-flight-mass spectrometry followed by evaluation via non-targeted data analysis. Internal standardization and appropriate quality control strategies have been implemented into the workflow for reduction of possible methodological biases influencing data interpretation. Emphasis was placed on the assessment of different blank elimination steps and the final blank elimination strategy is reported. The spatial study of the selected riverbank filtration site revealed a homogenous composition of the filtered water s led at 11 different locations across the 32,000 m 2 site, except for one s ling location in a zone of the aquifer, which was only weakly connected to the well field in terms of hydrogeological conditions. The examination of time-dependent changes of the composition of surface and groundwater obtained at the riverbank filtration system revealed that the non-targeted workflow is fit-for-purpose regarding the assessment the stability of filtration efficiency and compound residence time in the riverbank filtration compartment. In total, 677 compounds were selected for the investigation of the time-dependent variations of the filtration process. Analysis of the signal intensities of these compounds revealed that the riverbank filtration is significantly reducing the intensity and number of compounds present in surface water over a wide polarity range. In addition, the method enabled the determination of compound residence times in the riverbank filtration system ranging from 5 to 7 days.
Publisher: Wiley
Date: 02-05-2019
DOI: 10.1002/RCM.8420
Publisher: Springer Science and Business Media LLC
Date: 09-12-2020
DOI: 10.1007/S11103-020-01098-5
Abstract: LC-MS based metabolomics approach revealed that putative metabolites other than flavonoids may significantly contribute to the sexual compatibility reactions in Prunus armeniaca . Possible mechanisms on related microtubule-stabilizing effects are provided. Identification of metabolites playing crucial roles in sexual incompatibility reactions in apricot ( Prunus armeniaca L.) was the aim of the study. Metabolic fingerprints of self-compatible and self-incompatible apricot pistils were created using liquid chromatography coupled to time-of-flight mass spectrometry followed by untargeted compound search. Multivariate statistical analysis revealed 15 significant differential compounds among the total of 4006 and 1005 aligned metabolites in positive and negative ion modes, respectively. Total explained variance of 89.55% in principal component analysis (PCA) indicated high quality of differential expression analysis. The statistical analysis showed significant differences between genotypes and pollination time as well, which demonstrated high performance of the metabolic fingerprinting and revealed the presence of metabolites with significant influence on the self-incompatibility reactions. Finally, polyketide-based macrolides similar to peloruside A and a hydroxy sphingosine derivative are suggested to be significant differential metabolites in the experiment. These results indicate a strategy of pollen tubes to protect microtubules and avoid growth arrest involved in sexual incompatibility reactions of apricot.
Publisher: American Chemical Society (ACS)
Date: 12-05-2022
Publisher: Elsevier BV
Date: 07-2010
DOI: 10.1016/J.CHROMA.2010.05.002
Abstract: A gradient kinetic plot method is used for theoretical characterisation of the performance of polymeric particulate anion exchange columns for gradient separations of small inorganic anions. The method employed requires only information obtained from a series of isocratic column performance measurements and in silico predictions of retention time and peak width under gradient conditions. Results obtained under practically constrained conditions provide parameters for the generation of high peak capacities and rapid peak production for fast analysis to be determined. Using this prediction method, a maximum theoretical peak capacity of 84 could be used to achieve separation of 26 components using a 120min gradient (R(s)>1). This approach provides a highly convenient tool for development of both mono- and multidimensional ion chromatography (IC) methodologies as it yields comprehensive understanding of the influence of gradient slope, analysis time, column length and temperature upon kinetically optimised gradient performance.
Publisher: Springer Science and Business Media LLC
Date: 16-12-2019
Publisher: Elsevier BV
Date: 12-2019
DOI: 10.1016/J.TALANTA.2019.120147
Abstract: In this study, we present a novel selective cleanup/enrichment method based on metal oxide solid phase extraction combined with quantitative gas chromatography-tandem mass spectrometry and ion exchange chromatography-tandem mass spectrometry for the analysis of phosphorylated metabolites in yeast cell extracts relevant to biotechnological processes. Following screening of several commercially available metal oxide-based enrichment materials, all steps of the enrichment process (loading, washing and elution) were optimized for both the selective enrichment of 12 phosphorylated compounds from the glycolysis and pentose phosphate pathways, and the simultaneous removal of highly abundant matrix components such as organic acids and sugars. The full analytical workflow was then validated to meet the demands of accurate quantification of phosphorylated metabolites in yeast (Pichia pastoris) cell extracts using the best performing material and cleanup/enrichment method combined with quantification strategies based on internal standardization with isotopically labeled internal standards and external calibration. A good recovery (>70%) for 5 of the 12 targeted phosphorylated compounds with RSDs of less than 6.0% was obtained while many sugars, organic acids and amino acids were removed (>99% of glucose, and >95% of aspartate, succinate, glutamate, alanine, glycine, serine, threonine, proline, and valine). The use of isotopically labeled internal standards added to the s les prior to SPE, enables accurate quantification of the metabolites as it compensates for errors introduced during s le pretreatment and GC-MS or LC-MS analysis. To the best of our knowledge, this is the first time an effective and selective metal oxide-based affinity chromatography cleanup/enrichment method was designed and applied successfully for intracellular phosphorylated metabolites.
Publisher: American Chemical Society (ACS)
Date: 09-2202
Publisher: Elsevier BV
Date: 10-2201
Publisher: American Chemical Society (ACS)
Date: 16-08-2017
Publisher: American Chemical Society (ACS)
Date: 11-07-2022
DOI: 10.26434/CHEMRXIV-2022-87K68
Abstract: Steroids play key roles in various biological processes and are characterized by many isomeric variants which makes their unambiguous identification challenging. Ion mobility-mass spectrometry (IM-MS) has been proposed as a suitable platform for this application, particularly using collision cross section (CCS) databases obtained from differ-ent commercial IM-MS instruments. CCS is foreseen as an ideal additional identification parameter for steroids as long-term repeatability and interlaboratory reproducibility of this measurand are excellent and matrix effects are negligible. While excellent results were demonstrated for in idual IM-MS technologies, a systematic comparison of CCS derived from all major commercial IM-MS technologies has not been performed. To address this gap, a comprehensive interlabor-atory comparison of 142 CCS values derived from drift tube (DTIM-MS), traveling wave (TWIM-MS) and trapped ion mo-bility (TIM-MS) platforms using a set of 87 steroids was undertaken. Besides delivering three instrument-specific CCS databases, systematic comparisons revealed excellent interlaboratory performance for 95% of the ions with CCS biases within ±1% for TIM-MS and within ±2% for TWIM-MS with respect to DTIM-MS values. However, a small fraction of ions ( .5 %) showed larger biases of up to 7% indicating that differences in the ion conformation s led on different in-strument types need to be further investigated. Systematic differences between CCS derived from different IM-MS analyz-ers and implications on the applicability for non-targeted analysis are critically discussed. To the best of our knowledge this is the most comprehensive interlaboratory study comparing CCS from three different IM-MS technologies for analysis of steroids and small molecules in general.
Publisher: Elsevier BV
Date: 2016
Publisher: Wiley
Date: 03-2016
Publisher: Springer US
Date: 16-11-2019
DOI: 10.1007/978-1-0716-0030-6_4
Abstract: This chapter describes the developments in drift-tube ion mobility-mass spectrometry (DTIM-MS) that have driven application development in 'omics analyses. Harnessing the additional, orthogonal separation that DTIM provides increased confidence in compound identifications as the mass spectral complexity can be reduced and mobility-derived parameters (most prominently the collision cross section, CCS) used to support identity confirmation goals for a variety of 'omics application areas. Presented within this contribution is a methodology for improving the transmission and maintaining accurate determination of drift time-derived CCS (
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/CH10088
Abstract: Oligo(acrylic acid) efficiently stabilizes polymeric particles, especially particles produced by reversible addition–fragmentation chain transfer (RAFT) (as hydrophilic block of an hiphilic copolymer). Capillary electrophoresis (CE) has a far higher resolution power to separate these oligomers than the commonly used size exclusion chromatography. Coupling CE to electrospray ionization mass spectrometric detection unravels the separation mechanism. CE separates these oligomers, not only according to their degree of polymerization, but also according to their tacticity, in agreement with NMR analysis. Such analysis will provide insight into the role of these oligomers as stabilizers in emulsion polymerization, and into the mechanism of the RAFT polymerization with respect to degree of polymerization and tacticity.
Publisher: Elsevier BV
Date: 09-2016
Publisher: Elsevier BV
Date: 12-2019
DOI: 10.1016/J.ACA.2019.08.037
Abstract: In this study, we report a methodology based on reversed phase LC (RP-LC) and hydrophilic interaction chromatography (HILIC) separations coupled to ion mobility (IM) and high resolution mass spectrometry (HR-MS) for the detailed analysis of hydrolysable tannins. The application of this approach to the analysis of an industrial chestnut (Castanea sativa, wood chips) tannin extract is demonstrated. A total of 38 molecular species, including a large number or isomers, were identified in this s le based on HR-MS
Publisher: Elsevier BV
Date: 11-2012
DOI: 10.1016/J.CHROMA.2012.09.033
Abstract: The influence of mobile phase solvent composition and consequently retention factor on the chromatographic performance for a set of small molecules was studied using a commercially available poly(styrene-co- inyl benzene) analytical scale porous polymeric monolithic column as an ex le. Chromatographic elution performance was studied across retention factors from close to 0 up to 100 realized for a set of structurally similar small molecules in a binary reversed-phase solvent environment of acetonitrile and water. By altering the mobile phase composition from volume fractions of acetonitrile of just 10% (v/v) to only acetonitrile it was systematically shown that gel porosity of the monolithic column plays a dominant role in modulating mass transport and the associated chromatographic efficiency in a consistent manner. Up to a sixfold difference in plate height was recorded for the most strongly retained hydrophobic solute (ethylbenzene) at a constant, low flow velocity simply by varying the amount of acetonitrile in the mobile phase. Plate height curves recorded for the set of solutes that comprise benzene, toluene, ethylbenzene as well as phenol and benzyl alcohol further demonstrate the importance of functional group content of the solute and the modulated porous gel structure on mass transport. These results highlight some important practical considerations for characterizing the chromatographic properties of any polymeric monolithic column. First, it is imperative that any chromatographic performance characterization using plate height data explicitly considers the influence of mobile phase composition, retention factor, molecular size and functional groups of the probe solute. Second, as the physicochemical conditions of the material are directly reflected in the gel porosity, a range of different mobile phase compositions, retention factors and probe-specific effects must be investigated to yield a fair appraisal of the chromatographic performance.
Publisher: Elsevier BV
Date: 09-2020
Publisher: Elsevier BV
Date: 2022
Publisher: Elsevier BV
Date: 05-2010
DOI: 10.1016/J.CHROMA.2010.03.033
Abstract: Alternative approaches to conventional acetonitrile gradient methods for reversed-phase liquid chromatographic analysis of intact proteins have been investigated using commercial poly(styrene-co- inylbenzene) monolithic columns (Dionex ProSwift RP-2H and RP-4H). Alternative solvents to acetonitrile (2-propanol and methanol) coupled with elevated temperatures demonstrated complementary approaches to adjusting separation selectivity and reducing organic solvent consumption. Measurements of peak area at increasing isothermal temperature intervals indicated that only minor (<5%) decreases in detectable protein recovery occurred between 40 and 100 degrees C on the timescale of separation (2-5 min). The reduced viscosity of a 2-propanol/water eluent at elevated temperatures permitted coupling of three columns to increase peak production (peaks/min) by 16.5%. Finally, narrow-bore (1 mm i.d.) columns were found to provide a more suitable avenue to fast, high temperature (up to 140 degrees C) separations.
Publisher: American Chemical Society (ACS)
Date: 19-03-2012
DOI: 10.1021/AC300161B
Abstract: In this study we introduce the implementation of rapid temperature pulses for selectivity tuning in capillary liquid chromatography. Short temperature pulses improved resolution in discrete sections of chromatograms, demonstrated for ion-exchange chromatography (IC) and hydrophilic interaction chromatography (HILIC) modes. Using a resistively heated column module capable of accurate and rapid temperature changes, this concept is first illustrated with separations of small anions by IC using a packed capillary column as well as a series of nucleobases and nucleosides by HILIC using a silica monolithic column with zwitterionic functionality (ZIC-HILIC). Both positive (increasing temperature) and negative temperature pulses are demonstrated to produce significant changes in selectivity and are useful approaches for improving resolution between coeluted compounds. The approach was shown to be reproducible over a large number of replicates. Finally, the use of temperature gradients as well as other complex temperature profiles was also examined for both IC and HILIC separations.
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3CP01968C
Abstract: Protonation and deprotonation sites of diaminobenzoic acid and aminophthalic acid isomers were investigated using ion mobility-mass spectrometry and computational methods.
Publisher: Wiley
Date: 03-06-2021
Abstract: In a previous work, we explored zone broadening and the achievable plate numbers in linear drift tube ion mobility‐mass spectrometry through developing a plate‐height model [1]. On the basis of these findings, the present theoretical study extends the model by exploring peak‐to‐peak resolution and peak capacity in ion mobility separations. The first part provides a critical overview of chromatography‐influenced resolution equations, including refinement of existing formulae. Furthermore, we present exact resolution equations for drift tube ion mobility spectrometry based on first principles. Upon implementing simple modifications, these exact formulae could be readily extended to traveling wave ion mobility separations and to cases when ion mobility spectrometry is coupled to mass spectrometry. The second part focuses on peak capacity. The well‐known assumptions of constant plate number and constant peak width form the basis of existing approximate solutions. To overcome their limitations, an exact peak capacity equation is derived for drift tube ion mobility spectrometry. This exact solution is rooted in a suitable physical model of peak broadening, accounting for the finite injection pulse and subsequent diffusional spreading. By borrowing concepts from the theoretical toolbox of chromatography, we believe that the present study will help in integrating ion mobility spectrometry into the unified language of separation science.
Publisher: Springer Science and Business Media LLC
Date: 12-01-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D2SC06487A
Abstract: 3-Pyridylcarbinol ester derivatization introduces a universal probe for cryogenic gas-phase infrared spectroscopy of fatty acids that enables assignment of the position and configuration of carbon–carbon double bonds even in the presence of isomers.
Publisher: Elsevier
Date: 2018
Publisher: Elsevier BV
Date: 11-2011
DOI: 10.1016/J.CHROMA.2011.09.047
Abstract: The kinetic optimisation of open-tubular liquid chromatography (OTLC) columns has been revisited by taking the thick-film effects for porous coatings on retention, column resistance, band broadening and mass loadability into account. Considering the most advantageous case (i.e. where the retentive layer allows for the same high internal diffusion coefficient as conventional porous particles), calculations show the need for the development of coating procedures leading to porous films filling up approximately 50-70% of the total column diameter. Furthermore, to achieve optimum kinetic performance for separations of small molecules with total analysis times of less than 8h (k'=9), total column diameters should be less than 6 μm with lengths typically greater than 0.8m for N values of 125,000-500,000 at a pressure of 400 bar. The use of elevated temperature LC (90°C) is also shown to increase the allowable total column diameter to up to 9 μm for a larger range of N values (100,000-880,000).
Publisher: American Chemical Society (ACS)
Date: 19-08-2020
Publisher: Elsevier BV
Date: 10-2015
DOI: 10.1016/J.CHROMA.2015.09.009
Abstract: In the domain of liquid phase separations, the quality of separation obtainable is most readily gauged by consideration of classical chromatographic peak capacity theory. Column-based multidimensional strategies for liquid chromatography remain the most attractive and practical route for increasing the number of spatially resolved components in order to reduce stress on necessary mass spectrometric detection. However, the stress placed on a chromatographic separation step as a second dimension in a comprehensive online methodology (i.e. online LC×LC) is rather high. As an alternative to online LC×LC combinations, coupling of HPLC with ion mobility spectrometry hyphenated to mass spectrometry (IMS-MS) has emerged as an attractive approach to permit comprehensive s ling of first dimension chromatographic peaks and subsequent introduction to an orthogonal IMS separation prior to measurement of ions by a mass spectrometer. In the present work, utilization of classical peak capacity and ion mobility theory allows theoretical assessment of the potential of two- (LC×IMS-MS) or even three-dimensional (LC×LC×IMS-MS) experimental setups to enhance peak capacity and, therefore, the number of correctly annotated features within the framework of complex, non-targeted analysis problems frequently addressed using HPLC-MS strategies. Theoretical calculations indicate that newly-available drift tube IMS-MS instrumentation can yield peak capacities of between 10 and 40 using nitrogen drift gas for typical non-targeted metabolomic, lipidomic and proteomic applications according to the expected reduced mobilities of components in the respective s les. Theoretically, this approach can significantly improve the overall peak capacity of conventional HPLC-(MS) methodologies to in excess of 10(4) depending upon the column length and gradient time employed. A more elaborate combination of LC×LC×IMS-MS would improve the ion suppression limitation and possibly allow access to theoretically even higher peak capacities, but such a combination may render the IMS separation practically redundant as well as imparting the well-known dilution problems associated with LC×LC. Finally, some predictions for the separation of co-eluted isobaric compounds can also be made by considering the required peak-to-peak resolution for acceptable IMS separation. The here-described theoretical predication approach can be used to aid method development for HPLC×IMS-MS and is also accompanied by some practical considerations that should be contemplated in associated non-targeted analysis workflows.
Publisher: Elsevier BV
Date: 07-2023
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0AN00433B
Abstract: In analogy to chromatography, a plate-height model of drift tube ion mobility-mass spectrometry is presented that describes zone broadening and resolving power in ion mobility separations.
Publisher: Elsevier BV
Date: 09-2015
DOI: 10.1016/J.WASMAN.2015.05.035
Abstract: Engineered nanomaterials (ENMs) are already extensively used in erse consumer products. Along the life cycle of a nano-enabled product, ENMs can be released and subsequently accumulate in the environment. Material flow models also indicate that a variety of ENMs may accumulate in waste streams. Therefore, a new type of waste, so-called nanowaste, is generated when end-of-life ENMs and nano-enabled products are disposed of. In terms of the precautionary principle, environmental monitoring of end-of-life ENMs is crucial to allow assessment of the potential impact of nanowaste on our ecosystem. Trace analysis and quantification of nanoparticulate species is very challenging because of the variety of ENM types that are used in products and low concentrations of nanowaste expected in complex environmental media. In the framework of this paper, challenges in nanowaste characterisation and appropriate analytical techniques which can be applied to nanowaste analysis are summarised. Recent case studies focussing on the characterisation of ENMs in waste streams are discussed. Most studies aim to investigate the fate of nanowaste during incineration, particularly considering aerosol measurements whereas, detailed studies focusing on the potential release of nanowaste during waste recycling processes are currently not available. In terms of suitable analytical methods, separation techniques coupled to spectrometry-based methods are promising tools to detect nanowaste and determine particle size distribution in liquid waste s les. Standardised leaching protocols can be applied to generate soluble fractions stemming from solid wastes, while micro- and ultrafiltration can be used to enrich nanoparticulate species. Imaging techniques combined with X-ray-based methods are powerful tools for determining particle size, morphology and screening elemental composition. However, quantification of nanowaste is currently h ered due to the problem to differentiate engineered from naturally-occurring nanoparticles. A promising approach to face these challenges in nanowaste characterisation might be the application of nanotracers with unique optical properties, elemental or isotopic fingerprints. At present, there is also a need to develop and standardise analytical protocols regarding nanowaste s ling, separation and quantification. In general, more experimental studies are needed to examine the fate and transport of ENMs in waste streams and to deduce transfer coefficients, respectively to develop reliable material flow models.
Publisher: American Chemical Society (ACS)
Date: 05-12-2020
Abstract: In this study we report a detailed investigation of the polyphenol composition of
Publisher: Wiley
Date: 29-11-2014
Abstract: The combination of CE and MS is now a widely used tool that can provide a combination of high resolution separations with detailed structural information. Recently, we highlighted the benefits of an approach to add further functionality to this well-established hyphenated technique, namely the possibility to perform chemical reactions within the sheath-liquid of the CE-MS interface . Apart from using hydrogen/deuterium exchange for online determination of numbers of exchangeable protons, the addition of DPPH• (2,2-diphenyl-1-picrylhydrazyl) to the sheath-liquid can be used as a fast screening tool for studying antioxidant characteristics of in idual components. Such a CE-MS methodology allows rapid and information-rich analysis with minimal reagent and s le consumption to be performed. In the present work, we demonstrate the applicability of this approach for the characterization of phenolic plant extracts from the Labiatae family, namely Rosmarinus officinalis and Melissa officinalis. Using the described approach, a wide range of compounds (15 and 13 phenolic compounds, respectively) could be confidently identified using a combination of high resolution CE-MS separations with implementation of online deuterium exchange and DPPH• reactions. These compounds included polyphenols, phenolic acids, and triterpene acids. In conjunction with online MS/MS experiments, extensive structural information for aglyconic and glycosylated antioxidants present in the extracts could be obtained using simple experimental changes, which can be carried out prior to the purchasing of expensive chemical standards or the time-consuming preparative isolation of in idual compounds.
Publisher: Elsevier BV
Date: 07-2010
DOI: 10.1016/J.CHROMA.2010.05.066
Abstract: The first use of the kinetic plot method to characterise the performance of ion-exchange columns for separations of small inorganic anions is reported. The influence of analyte type (mono- and alent), particle size (5 and 9microm), temperature (30 and 60 degrees C) and maximum pressure drop upon theoretical extrapolations was investigated using data collected from anion-exchange polymeric particulate columns. The quality of extrapolations was found to depend upon the choice of analyte, but could be verified by coupling a series of columns to demonstrate some practical solutions for ion chromatography separations requiring relatively high efficiency. Separations of small anions yielding 25-40,000 theoretical plates using five serially connected columns (9microm particles) were obtained and yielded deviations of <15% from the kinetic plot predictions. While this approach for achieving high efficiencies results in a very long analysis time (t(0)=21min), separations yielding approximately 10,000 theoretical plates using two serially connected columns (t(0) 10min).
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D2CC05237G
Abstract: Here, we show how intramolecular proton transfer can be induced and monitored with the ex le of polycyclic aromatic amines using in-source ion-activation and ion mobility-mass spectrometry.
Publisher: Elsevier BV
Date: 08-2017
Publisher: Springer Science and Business Media LLC
Date: 12-08-2022
DOI: 10.1007/S00216-022-04263-5
Abstract: The major benefits of integrating ion mobility (IM) into LC–MS methods for small molecules are the additional separation dimension and especially the use of IM-derived collision cross sections ( CCS ) as an additional ion-specific identification parameter. Several large CCS databases are now available, but outliers in experimental interplatform IM-MS comparisons are identified as a critical issue for routine use of CCS databases for identity confirmation. We postulate that different routine external calibration strategies applied for traveling wave (TWIM-MS) in comparison to drift tube (DTIM-MS) and trapped ion mobility (TIM-MS) instruments is a critical factor affecting interplatform comparability. In this study, different external calibration approaches for IM-MS were experimentally evaluated for 87 steroids, for which TW CCS N2 , DT CCS N2 and TIM CCS N2 are available. New reference CCS N2 values for commercially available and class-specific calibrant sets were established using DTIM-MS and the benefit of using consolidated reference values on comparability of CCS N2 values assessed. Furthermore, use of a new internal correction strategy based on stable isotope labelled (SIL) internal standards was shown to have potential for reducing systematic error in routine methods. After reducing bias for CCS N2 between different platforms using new reference values (95% of TW CCS N2 values fell within 1.29% of DT CCS N2 and 1.12% of TIM CCS N2 values, respectively), remaining outliers could be confidently classified and further studied using DFT calculations and CCS N2 predictions. Despite large uncertainties for in silico CCS N2 predictions, discrepancies in observed CCS N2 values across different IM-MS platforms as well as non-uniform arrival time distributions could be partly rationalized.
Publisher: Springer Science and Business Media LLC
Date: 13-07-2019
DOI: 10.1007/S00216-019-02021-8
Abstract: This study of ion accumulation/release behavior relevant to ion mobility-mass spectrometry (IM-MS) as employed for non-targeted metabolomics involves insight from theoretical studies, and controlled reference experiments involving measurement of low and high molecular mass metabolites in varying concentrations within a complex matrix (yeast extracts). Instrumental settings influencing ion trapping (accumulation time) and release conditions in standard and multiplexed operation have been examined, and translation of these insights to liquid chromatography (LC) in combination with drift tube IM-MS measurements has been made. The focus of the application is non-targeted metabolomics using carefully selected s les to allow quantitative interpretations to be made. Experimental investigation of the IM-MS ion utilization efficiency particularly focusing on the use of the Hadamard transform multiplexing with 4-bit pseudo-random pulsing sequence for assessment of low and high molecular mass metabolites is compared with theoretical modeling of gas-phase behavior of small and large molecules in the IM trapping funnel. Increasing the trapping time for small metabolites with standard IM-MS operation is demonstrated to have a deleterious effect on maintaining a quantitative representation of the metabolite abundance. The application of these insights to real-world non-targeted metabolomics assessment of intracellular extracts from biotechnologically relevant production processes is presented, and the results were compared to LC×IM-MS measurements of the same s les. Spiking of a uniformly
Publisher: Elsevier BV
Date: 04-2022
Publisher: Oxford University Press (OUP)
Date: 2022
Abstract: The low solubility of inorganic iron(III) in seawater leads to very limited availability of this important micronutrient for marine organisms. Estuarine or oceanic iron is almost entirely bound to organic ligands of mainly unknown chemical structure. In this context, riverine input of iron rich, land-derived dissolved organic matter (DOM) can play an important role in coastal areas and investigation of potential Fe-ligands in DOM is of high interest. Previous studies have suggested that iron is predominantly bound to the high molecular weight fraction of DOM, but distributed over the entire size range. Logically, structural elucidation needs to start from the smallest building blocks. A model study targeting low molecular weight iron-binding constituents in Suwannee River natural organic matter (NOM) using Fe-loaded Chelex or silica for immobilized-metal affinity (IMAC)-based fractionation was undertaken. The binding strengths of different compounds could be qualitatively assessed using a differential analysis workflow. IMAC-fractionated s les were acidified and analyzed via liquid chromatography high resolution mass spectrometry (LC-HRMS) and molecular formulas were assigned using state of the art software. A total of 144 Fe-binding constituents in Suwannee River NOM were found to be of interest with the largest number observed to interact with Chelex at pH 4 (55%), and the smallest with silica at neutral pH (24%). Most binding constituents were found in the lignin- and tannin-type region of the van Krevelen plot. Results from this study support the hypothesis that very low molecular weight constituents (below 300 Da) can play a role in the iron binding mechanism of DOM and demonstrate that the employed analytical workflow is suitable for their detection.
Publisher: American Chemical Society (ACS)
Date: 02-11-2018
DOI: 10.26434/CHEMRXIV.7072070.V4
Abstract: Here we present a guide on ion mobility mass spectrometry experiments, which covers both linear and nonlinear methods: what is measured, how the measurements are done, and how to report the results, including the uncertainties on mobility and collision cross section values. The guide aims to clarify some possibly confusing concepts, and the reporting recommendations should help researchers, authors and reviewers to contribute comprehensive reports, so that the ion mobility data can be reused more confidently. Starting from the concept of the definition of the measurand, we emphasize that (i) mobility values (K0) depend intrinsically on ion structure, the nature of the bath gas, temperature, and E/N, (ii) ion mobility does not measure surfaces directly, but collision cross section (CCS) values are derived from mobility values using a physical model, (iii) methods relying on calibration are empirical (and thus may provide method-dependent results) only if the gas nature, temperature or E/N cannot match those of the primary method. Our analysis highlights the urgency of a community effort towards establishing primary standards and reference materials for ion mobility, and provides recommendations to do so.
Publisher: Wiley
Date: 26-02-2016
Publisher: Elsevier BV
Date: 09-2016
DOI: 10.1016/J.ACA.2016.07.033
Abstract: Fermentation and cell culture biotechnology in the form of so-called "cell factories" now play an increasingly significant role in production of both large (e.g. proteins, biopharmaceuticals) and small organic molecules for a wide variety of applications. However, associated metabolic engineering optimisation processes relying on genetic modification of organisms used in cell factories, or alteration of production conditions remain a challenging undertaking for improving the final yield and quality of cell factory products. In addition to genomic, transcriptomic and proteomic workflows, analytical metabolomics continues to play a critical role in studying detailed aspects of critical pathways (e.g. via targeted quantification of metabolites), identification of biosynthetic intermediates, and also for phenotype differentiation and the elucidation of previously unknown pathways (e.g. via non-targeted strategies). However, the ersity of primary and secondary metabolites and the broad concentration ranges encompassed during typical biotechnological processes means that simultaneous extraction and robust analytical determination of all parts of interest of the metabolome is effectively impossible. As the integration of metabolome data with transcriptome and proteome data is an essential goal of both targeted and non-targeted methods addressing production optimisation goals, additional s le preparation steps beyond necessary s ling, quenching and extraction protocols including clean-up, analyte enrichment, and derivatisation are important considerations for some classes of metabolites, especially those present in low concentrations or exhibiting poor stability. This contribution critically assesses the potential of current s le preparation strategies applied in metabolomic studies of industrially-relevant cell factory organisms using mass spectrometry-based platforms primarily coupled to liquid-phase s le introduction (i.e. flow injection, liquid chromatography, or capillary electrophoresis). Particular focus is placed on the selectivity and degree of enrichment attainable, as well as demands of speed, absolute quantification, robustness and, ultimately, consideration of fully-integrated bioanalytical solutions to optimise s le handling and throughput.
Publisher: Elsevier BV
Date: 09-2014
Publisher: Wiley
Date: 02-2019
DOI: 10.1002/MAS.21585
Publisher: Wiley
Date: 23-11-2017
Abstract: Ion mobility spectrometry is an analytical technique known for more than 100 years, which entails separating ions in the gas phase based on their size, shape, and charge. While ion mobility spectrometry alone can be useful for some applications (mostly security analysis for detecting certain classes of narcotics and explosives), it becomes even more powerful in combination with mass spectrometry and high-performance liquid chromatography. Indeed, the limited resolving power of ion mobility spectrometry alone can be tackled when combining this analytical strategy with mass spectrometry or liquid chromatography with mass spectrometry. Over the last few years, the hyphenation of ion mobility spectrometry to mass spectrometry or liquid chromatography with mass spectrometry has attracted more and more interest, with significant progresses in both technical advances and pioneering applications. This review describes the theoretical background, available technologies, and future capabilities of these techniques. It also highlights a wide range of applications, from small molecules (natural products, metabolites, glycans, lipids) to large biomolecules (proteins, protein complexes, biopharmaceuticals, oligonucleotides).
Publisher: Oxford University Press (OUP)
Date: 12-05-2017
Abstract: Zinc is a crucial mineral for all organisms as it is an essential cofactor for the proper function of a plethora of proteins and depletion of zinc causes oxidative stress. Glutathione is the major redox buffering agent in the cell and therefore important for mitigation of the adverse effects of oxidative stress. In mammalian cells, zinc deficiency is accompanied by a glutathione depletion. In the yeast Saccharomyces cerevisiae, the opposite effect is observed: under low zinc conditions, an elevated glutathione concentration is found. The main regulator to overcome zinc deficiency is Zap1p. However, we show that Zap1p is not involved in this glutathione accumulation phenotype. Furthermore, we found that in glutathione-accumulating strains also the metal ion-binding phytochelatin-2, which is an oligomer of glutathione, is accumulated. This increased phytochelatin concentration correlates with a lower free zinc level in the vacuole. These results suggest that phytochelatin is important for zinc buffering in S. cerevisiae and thus explains how zinc homeostasis is connected with glutathione metabolism.
Publisher: American Chemical Society (ACS)
Date: 31-05-2013
DOI: 10.1021/AC401303K
Abstract: Concerning polymeric monolithic materials utilized in separation science, the structural and mechanical characteristics from the nanoscopic to the macroscopic scale remain of great interest. Suitable analytical tools are urgently required to understand the polymer monolith's constituent structure, particularly in the case of nanoscale polymer properties that tend to develop gel porosity in contact with a mobile phase ultimately affecting the chromatographic performance. Herein described are our first findings from a characterization of commercially available analytical polymer monoliths based on styrene/ inylbenzene and methacrylate chemistries utilizing confocal Raman spectroscopy imaging and atomic force microscopy (AFM). Confocal Raman spectroscopy can be used to generate a three-dimensional representation of monoliths in both dry state and in contact with solvent. AFM force-indentation measurements on in idual cross-sectioned globular features permit detailed assessment of mechanical properties of the stationary phase. This approach allowed so far unprecedented insight and identification of a heterogeneous cross-link density distribution of polymer material within in idual globular features on a submicrometer scale.
Publisher: Elsevier BV
Date: 02-2018
DOI: 10.1016/J.CBPA.2017.10.015
Abstract: Non-targeted analysis of metabolites in hypothesis-generating workflows has proven its potential to answer essential questions that arise when dealing with complex biological systems. Nevertheless, tracking changes in perturbed systems via accurate quantification and the identification process itself represent the most critical challenges in these workflows. Recent advances in ion mobility-mass spectrometry have enabled this technique to increase the confidence of metabolite annotation by introducing a complementary conditional molecular descriptor, that is collision cross section.
Publisher: Wiley
Date: 10-03-2011
Abstract: This HPLC tutorial focuses on the preparation and use of kinetic plots to characterise the performance in isocratic and gradient LC. This graphical approach allows the selection of columns (i.e. optimum particle size and column length) and LC conditions (operating pressure and temperature) to generate a specific number of plates or peak capacity in the shortest possible analysis time. Instrument aspects including the influence of extra-column effects (maximum allowable system volume) and thermal operating conditions (oven type) on performance are discussed. In addition, the performance characteristics of porous-shell particle-packed columns and monolithic stationary phases are presented and the potential of future column designs is discussed.
Publisher: Wiley
Date: 08-2017
Abstract: Reversed-phase LC combined with high-resolution mass spectrometry (HRMS) is one of the most popular methods for cellular metabolomics studies. Due to the difficulties in analyzing a wide range of polarities encountered in the metabolome, 100%-wettable reversed-phase materials are frequently used to maximize metabolome coverage within a single analysis. Packed with silica-based sub-3 μm diameter particles, these columns allow high separation efficiency and offer a reasonable compromise for metabolome coverage within a single analysis. While direct performance comparison can be made using classical chromatographic characterization approaches, a comprehensive assessment of the column's performance for cellular metabolomics requires use of a full LC-HRMS workflow in order to reflect realistic study conditions used for cellular metabolomics. In this study, a comparison of several reversed-phase LC columns for metabolome analysis using such a dedicated workflow is presented. All columns were tested under the same analytical conditions on an LC-TOF-MS platform using a variety of authentic metabolite standards and biotechnologically relevant yeast cell extracts. Data on total workflow performance including retention behavior, peak capacity, coverage, and molecular feature extraction repeatability from these columns are presented with consideration for both nontargeted screening and differential metabolomics workflows using authentic standards and Pichia pastoris cell extract s les.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2AN35804B
Abstract: Within recent years there has been an increase in research focused on the design and application of organic polymer monoliths in all areas of separation science. This is largely driven by the theoretical and practical benefits that these materials should be able to provide, particularly in terms of improved biocompatibility and high permeability. This review summarises recent new developments in this field with a focus on new approaches to the design and synthesis of polymeric monolithic materials for analytical separation science. This includes the use of alternative synthetic methodologies such as the development of hyper-crosslinked monoliths, preparation of hybrid materials and incorporation of nanostructures in the polymeric scaffold. New and developing approaches for the structural characterisation of monolithic columns are also included. Finally, we critically discuss the current chromatographic performances achieved with this column technology as well as where future developments in this field may be directed.
Publisher: Elsevier BV
Date: 02-2021
Publisher: Elsevier BV
Date: 06-2010
DOI: 10.1016/J.CHROMA.2010.04.007
Abstract: A broad appraisal of the kinetic performance of organic polymeric monolithic columns is reported using commercially available poly(styrene-co- inylbenzene) monolithic columns (Dionex ProSwift RP-1S). Analysis of a protein digest s le at elevated temperatures (> or =80 degrees C) indicated no apparent analyte degradation using an inert polymeric stationary phase. Comparison between low molecular weight solute and peptide separations highlighted the markedly different mass transport processes observed on macroporous monolithic beds and an improved C term at elevated temperature in both instances. The current usefulness of this column format for biomolecule analysis was further studied via employment of a kinetic performance characterisation for the first time to provide direction for column development servicing this application.
Publisher: Wiley
Date: 18-02-2013
Abstract: Polyimides (PIs) are a group of widely used synthetic materials that service a variety of different purposes including microelectronics, insulating films and aerospace applications. Depending on the requirements (defined by the particular final product), the actual composition of PIs may show substantial chemical variation. To study this variation in chemical structure, CE-MS can be employed for the determination of PI composition following chemical degradation of the polymer s le. PI is chemically decomposed to corresponding aromatic diamine and carboxylic acid components using an alkali fusion reaction. Solid polymer s les are fused in a potassium hydroxide melt yielding reaction products that are diluted in acid and can be immediately analysed by CE coupled to a Q/TOF-MS with quantification performed using conventional UV detection. This approach involves a simple and rapid s le preparation yielding both qualitative and quantitative information regarding the chemical composition of the polymer. Application of the CE-MS approach is shown for a range of commercially available PI and poly(amide-imide) materials and the results are used to infer the respective chemical compositions.
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/B815886J
Abstract: Use of an organic polymeric monolithic stationary phase for high temperature liquid chromatography (HTLC) with a pure water eluent is demonstrated for the first time. Separations of n-alcohols at temperatures exceeding 200 degrees C were achieved with no statistically significant reduction in chromatographic performance evident after continuous operation for 1000 column volumes above 200 degrees C.
Publisher: Elsevier BV
Date: 05-2014
DOI: 10.1016/J.CHROMA.2014.04.002
Abstract: Conventional coupling of capillary electrophoresis with electrospray ionisation mass spectrometry typically relies on the use of a triaxial sheath-flow liquid interface to facilitate electrical contact and provide a stable electrospray. In this type of analysis, the use of additives in the sheath liquid itself can also be used to improve ionisation of analytes and even facilitate reactions between separation and detection steps (which we broadly term "sheath-flow chemistry"). In the present work, this concept is demonstrated using two types of sheath-flow reactions for CE coupled with quadrupole time-of-flight (Q-TOF) MS detection. Sheath liquid compositions containing deuterated solvents or DPPH (2,2-diphenyl-1-dipicrylhydrazyl) stable free-radicals yield useful additional structural information for separated analytes. Investigations of fundamental physical and chemical characteristics of the sheath liquid coupling show their direct influence on the efficiency and some of the products of the respective reactions. For ex le, reducing the capillary internal diameter from 75 to 25μm increased the relative abundance of fully deuterated ions detected by 63-65% (5 exchangeable hydrogens) using constant sheath-flow conditions. Addition of 0.05-0.2mM DPPH to the sheath liquid reduced the peak total ion count obtained for typical antioxidant species by 20 to >95% allowing strongly antioxidant species from mixtures to be readily identified and further studied. The presented approach allows a rapid and information-rich analysis to be performed with minimal reagent and s le consumption.
Location: Austria
Start Date: 2021
End Date: 2023
Funder: FWF Austrian Science Fund
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