ORCID Profile
0000-0002-8436-1836
Current Organisation
Deakin University
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Publisher: American Chemical Society (ACS)
Date: 08-06-2023
Publisher: Elsevier BV
Date: 10-2023
Publisher: Elsevier BV
Date: 11-2017
Publisher: American Chemical Society (ACS)
Date: 09-02-2023
Publisher: Elsevier BV
Date: 10-2020
Publisher: Springer Science and Business Media LLC
Date: 22-01-2019
DOI: 10.1007/S00216-019-01579-7
Abstract: Sapucainha oil, which may be used to treat leprosy, comprises straight chain and cyclic fatty acids (FA), and triacylglycerols (TAG). The FA and TAG content of the oil s le was analysed using gas chromatography-electron ionisation mass spectrometry (GC-EIMS). FA analysis was performed after derivatisation to fatty acid methyl esters (FAME). For free FA and TAG analysis, the oil s le was dissolved in hexane and injected into a short, high-temperature column, for GC with MS analysis. Free FA and FAME were tentatively identified based on mass spectrum information of their molecular and fragment ions, as well as library matching. Overlapping TAG peaks were deconvoluted based on mass fingerprint data. The FA composition was utilised to predict possible TAG identities. FA residues of TAG were identified based on characteristic fragment ions, such as [M-RCO
Publisher: MDPI AG
Date: 13-05-2020
DOI: 10.3390/SEPARATIONS7020027
Abstract: Molecular spectroscopic detection techniques, such as Fourier transform infrared spectroscopy (FTIR), provides additional specificity for isomers where often mass spectrometry (MS) fails, due to similar fragmentation patterns. A hyphenated system of gas chromatography (GC) with FTIR via a light-pipe interface is reported in this study to explore a number of GC–FTIR analytical capabilities. Various compound classes were analyzed—aromatics, essential oils and oximes. Variation in chromatographic peak parameters due to the light-pipe was observed via sequentially-located flame ionization detection data. Unique FTIR spectra were observed for separated mixtures of essential oil isomers having similar mass spectra. Presentation of GC×FTIR allows a ‘comprehensive’-style experiment to be developed. This was used to obtain spectroscopic/separation profiles for interconverting oxime species with their in idual spectra in the overlap region being displayed on a color contour plot. Partial least square regression provides multivariate quantitative analysis of co-eluting cresol isomers derived from GC–FTIR data. The model resulted in an R2 of 0.99. Prediction was obtained with R2 prediction value of 0.88 and RMSEP of 0.57, confirming the method’s suitability. This study explores the potential of GC–FTIR hyphenation and re-iterates its value to derive unambiguous and detailed molecular information which is complementary to MS.
Publisher: Elsevier
Date: 2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9AN00990F
Abstract: Oxime E / Z isomers interconvert on GC columns they can be in idually monitored using FTIR to provide profiles of each isomer.
Publisher: American Chemical Society (ACS)
Date: 15-05-2015
DOI: 10.1021/ACS.ANALCHEM.5B00953
Abstract: Comprehensive two-dimensional gas chromatography hyphenated with accurate mass time-of-flight mass spectrometry (GC × GC-accTOFMS) was applied for improved analytical accuracy of saffron analysis, by using retention indices in the two-dimensional separation. This constitutes 3 dimensions of identification. In addition to accTOFMS specificity, and first dimension retention indices ((1)I), a simple method involving direct multiple injections with stepwise isothermal temperature programming is described for construction of isovolatility curves for reference alkane series in GC × GC. This gives access to calculated second dimension retention indices ((2)I). Reliability of the calculated (2)I was evaluated by using a Grob test mixture, and saturated alkanes, revealing good correlation between previously reported I values from the literature, with R(2) correlation being 0.9997. This essentially recognizes the retention property of peaks in the GC × GC 2D space as being reducible to a retention index in each dimension, which should be a valuable tool supporting identification. The benefit of (2)I data, in supplementing (1)I and MS library matching, was clearly demonstrated by the progressive reduction of the number of possible compound matches for peaks observed in saffron. 114 analytes were assessed according to (1)I and (2)I values within ±20 index unit of reference values, and by MS spectrum matching above a match statistic of 750 (including mass accuracy of the molecular ion <20 ppm) and their possible identities derived. The described method provides a new avenue to utilize the full capability of the two-dimensional separation (GC × GC), in combination with MS library matching in complex s le analysis, to provide improved component identification.
Publisher: Elsevier BV
Date: 03-2019
Publisher: MDPI AG
Date: 27-08-2021
Abstract: The volatile profile of raw beef contains vital information related to meat quality and freshness. This qualitative study examines the effect of packaging system on the formation and release of volatile organic compounds (VOCs) from raw beef over time, relative to the packaging best before date (BBD). The three packaging systems investigated were modified atmospheric packaging, vacuum packaging, and cling-wrapped packaging. Porterhouse steak s les with the same BBD were analysed from 3 days before to 3 days after the BBD. VOCs were detected via preconcentration using solid-phase microextraction combined with gas chromatography–accurate mass quadrupole time-of-flight mass spectrometry. In total, 35 different VOCs were tentatively identified. Interestingly, there was no clear relationship of the VOCs detected between the three packaging systems, with only carbon disulphide and acetoin, both known volatiles of beef, detected in all three. This is the first study to investigate the effects of commercial packaging systems on VOC formation it provides an understanding of the relationship of VOCs to the BBD that is essential for the development of on-pack freshness and quality sensors.
Publisher: Elsevier BV
Date: 2021
Publisher: Elsevier BV
Date: 09-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4CC00933A
Abstract: Polymorphic metal-organic framework (MOF) materials offer a platform for small-scale separation of complex mixtures of polycyclic aromatic hydrocarbons (PAHs) and polar compounds. Retention factors show dependence on both analyte dimensions and polarity, suggesting mixed-mode separation, allowing complete resolution of some analytes from multi-component mixtures.
Publisher: Wiley
Date: 05-03-2202
Abstract: In this study, the use of monolithic molecularly imprinted polymers in a micropipette tip format allowing the simple and fast extraction of flavonoids from standard solutions and a black tea s le is demonstrated. The imprinted polymer employed quercetin, methacrylic acid or 4-vinylpyridine, and ethylene glycol dimethacrylate as template, functional monomer, and cross-linker, respectively. Surface morphologies of the quercetin-imprinted polymers and the corresponding nonimprinted polymers were characterized by SEM. Extraction of flavonoid standards was performed to evaluate the selectivity and recovery with these imprinted and nonimprinted polymers. Flavonoid compositions in aliquots eluted from the tips were identified using fast GC with flame ionization detection. Maximum specific capacities of 0.2, 5.7, and 16.0 mg/g for catechin, morin, and quercetin, respectively, were obtained with the imprinted polymer prepared with methacrylic acid, with the corresponding recoveries of 99.8, 98.8, and 95.4%, respectively. Efficient extraction by the quercetin-imprinted polymer of epicatechin, catechin, and quercetin from an apple-flavored black tea s le was achieved, with GC-MS employed for compound identification for both the tea and extracted s les.
Publisher: Elsevier BV
Date: 11-2019
DOI: 10.1016/J.ACA.2019.07.013
Abstract: This study develops analytical approaches using comprehensive heart-cut multidimensional gas chromatography (H/C MDGC) to experimentally investigate effects of concentration and temperature on peak shapes and on kinetic analysis of E/Z isomerisation of oximes which undergo various extents of interconversion on
Publisher: Elsevier BV
Date: 06-2017
DOI: 10.1016/J.CHROMA.2017.04.037
Abstract: A precursor solution to the metal-organic framework (MOF), Cd(1,4,7,10-tetrakis(4-carboxybenzyl)-1,4,7,10-tetraazacyclododecane), was aged in a surface-functionalised 250μm-diameter capillary, to generate a film containing the constituents of the bulk phase crystalline material. EDX analysis revealed a higher ratio of ligand elements (C, N and O) to Cd in the capillary coated phase compared to that achieved from bulk synthesis in a vial. Separation performance of the coated capillary for gas chromatography (GC) was compared to the performance of the original MOF crystals packed in tips for liquid elution chromatography (LEC) towards the separation of polycyclic aromatic hydrocarbons (PAHs) and small probe analytes with different properties. This study showed that different retention mechanisms were observed for the same set of analytes in gas and liquid phases. Independently of the trend of vapour pressure difference, the GC result showed less specific size selective retention, but with stronger retention towards larger PAHs. A linear solvation energy relationship correlation further revealed enhanced retention contributions (positive stationary phase descriptor values) by cavity formation/dispersion interactions and H-bonding with acid functionality of the probe analytes in both GC and LEC (though stronger in LEC), whilst H-bonding with basic functional groups slightly increased retention in GC retention was strengthened by dipole-dipole/dipole-induced dipole interactions only in LEC.
Publisher: Springer Science and Business Media LLC
Date: 08-05-2019
Publisher: Elsevier BV
Date: 05-2019
DOI: 10.1016/J.FOODRES.2019.02.009
Abstract: A novel dynamic approach is described to profile volatile organic compound (VOC) and semi-VOC (SVOC) emission during coffee roasting aimed at analysing components present in the roasting plume, and to monitor their evolution during the process. Two sorbents - coconut shell charcoal (CSC) and styrene- inylbenzene resin (XAD-2) - were evaluated while collecting substances in four sequential time intervals (0-3, 3-6, 6-9 and 9-12 min). Extracted VOCs ( 400 Da. GC × GC resolved many co-eluting compounds observed in 1D GC and allowed chemical group type cluster analysis, revealing that many non-polar VOCs are observed within the 0-3 min interval, and that the release of polar and higher molar mass SVOCs were mostly found within the 3-6 min interval. These group-type cluster analyses offer a broad spectrum chemical profile of the released substances. It may also reveal detailed insights into the roast process evolution over time.
Publisher: Wiley
Date: 27-11-2018
Abstract: Homochiral metal–organic frameworks (MOFs) have gained much attention because of their chiral properties and disposition for chiral separation. However, the fabrication of high‐quality homochiral MOF membranes remains challenging because of the difficulty in controlling growth of MOF membranes with chiral functionalities. A homochiral zeolitic imidazolate framework‐8 (ZIF‐8) membrane is reported for efficient chiral separation. The membrane is synthesized by incorporating a natural amino acid, l ‐histidine ( l ‐His), into the framework of ZIF‐8. The homochiral l ‐His‐ZIF‐8 membrane exhibits a good selectivity for the R ‐enantiomer of 1‐phenylethanol over the S ‐enantiomer, showing a high enantiomeric excess value up to 76 %.
Publisher: Informa UK Limited
Date: 03-02-2015
Publisher: Elsevier BV
Date: 02-2021
Publisher: Elsevier BV
Date: 05-2018
DOI: 10.1016/J.CHROMA.2018.03.037
Abstract: Heart-cut multidimensional gas chromatographic (H/C MDGC) methods under suitable flow and high temperature (T) program conditions were developed to separate olive oil triacylglycerols (TAGs). Different column sets were selected for further evaluation, each with relatively short non-polar first dimension (
Publisher: Wiley
Date: 11-04-2014
Publisher: American Chemical Society (ACS)
Date: 06-02-2015
DOI: 10.1021/JP5103753
Abstract: In this study, the surface properties of type-B silica have been compared with an unmodified silica hydride phase, a diamond hydride phase and silica hydride phases modified with bidentate anchored octyl (BDC8), bidentate anchored octadecyl (BDC18), phenyl and cholesteryl groups. Atomic distributions of the surface elemental composition of each type of stationary phase were determined using energy-dispersive X-ray spectroscopy. For the type-B silica, unmodified silica hydride, diamond hydride as well as BDC18 and cholesteryl silica hydride phases, the increase in carbon contents correlated with more negative surface ζ potential values (R(2) = 0.92). The origin of these more negative ζ potentials has been evaluated with mobile phases up to 100% (v/v) methanol content, with this property attributed to either an increase in the amount of adsorbed hydroxide ions or a decrease in the amount of adsorbed protons on the surfaces modified silica hydride phases of higher carbon content. This property of chemically modified silica hydride phases is in accordance with the unique propensity for hydroxide ions to be preferentially adsorbed onto hydrophobic surfaces of low permittivity and effects due to the specific accumulated water molecules associated with the electrical interfacial double layer of the adsorbent.
Publisher: Wiley
Date: 15-12-2013
Abstract: Flavonoids represent one of the more abundant classes of phytochemicals. They are renowned for their health benefits against age-related ailments and diseases. Several chromatography techniques have underpinned many chemical analysis methods, developed for superior flavonoid separation and identification. Among these, GC is one of the most powerful tools in separation science, providing precise measurement of a wide range of flavonoids. Combined with various detectors - most commonly MS-GC offers a sensitive and accurate tool for quantitative and qualitative flavonoids analysis. This review features developments in the application of GC and MS for flavonoids determination during past decades, progressing to recent developments and considering future trends. The review will highlight the state-of-the-art of GC, with opportunities for multidimensional GC analysis also briefly discussed.
Publisher: Elsevier BV
Date: 05-2015
DOI: 10.1016/J.FOODCHEM.2014.10.083
Abstract: The extraction capabilities of a Diamond Hydride™ phase, as well as silica hydride phases modified with bidentate octadecyl (BDC(18)), phenyl or cholesteryl groups, were evaluated for the analysis of fatty acids, amino acids, sugars and sterols in a dark chocolate extract. These batch adsorption performances were investigated using either methanol or aqueous methanol as the solvent. The compositions of the extracted fractions were assessed by gas chromatography interfaced with quadrupole mass spectrometry (GC-qMS). The batch binding propensities of the various compound classes with silica hydride particles modified with immobilised phenyl groups or larger ligands followed trends predicted from linear solvation energy relationships. Both prediction and experiment revealed that better extraction results could be obtained with the phenyl, BDC(18) and cholesteryl hydride particles for the major chocolate components. Based on these results, separations in micro-pipette tip format with these three types of stationary phase particles have been undertaken.
Publisher: American Chemical Society (ACS)
Date: 23-09-2021
Publisher: Springer Science and Business Media LLC
Date: 17-02-2018
DOI: 10.1007/S00216-018-0944-7
Abstract: New generation inert ionic liquid (iIL) GC columns IL60i, IL76i and IL111i, comprising phosphonium or imidazolium cationic species, were investigated for separation of fatty acid methyl esters (FAME). In general, the iIL phases provide comparable retention times to their corresponding conventional columns, with only minor selectivity differences. The average tailing factors and peak widths were noticeably improved (reduced) for IL60i and IL76i, while they were slightly improved for IL111i. Inert IL phase columns were coupled with conventional IL columns in comprehensive two-dimensional GC (GC × GC) with a solid-state modulator which offers variable modulation temperature (T
Publisher: American Chemical Society (ACS)
Date: 02-02-2016
DOI: 10.1021/ACS.ANALCHEM.5B03688
Abstract: The selection of the best column sets is one of the most tedious processes in comprehensive two-dimensional gas chromatography (GC × GC) where a multitude of choices of column sets could be employed for an in idual s le analysis. We demonstrate analyte/stationary phase dependent selection approaches based on the linear solvation energy relationship (LSER), which is a reliable concept for the study of interaction mechanisms and retention prediction with a large database pool of columns and compounds. Good correlations between our predicted results, with experimental results reported in the literature, were obtained. The developed approaches were applied to the simulation of 157 920 in idual experiments in GC × GC, focusing on the application of 30 nonionic liquid and 111 ionic liquid (IL) stationary phases for separation of some ex le sets of model compounds present in practical s les. The best column sets for each s le separation could then be extracted according to maximizing orthogonality, which estimates the quality of separation.
Publisher: Elsevier BV
Date: 10-2023
Publisher: American Chemical Society (ACS)
Date: 17-12-2015
DOI: 10.1021/AC5030039
Abstract: In this study, a theoretical concept and method to achieve a degree of orthogonality in comprehensive two-dimensional gas chromatography (GC × GC) for separation of fatty acid methyl esters (FAME) by using a single ionic liquid (IL) stationary phase (1-phase-GC × GC) were established. The 1-phase system comprises a long IL column and shorter IL column of the same phase before and after the modulation region, operated under temperature-programmed conditions. Initial isothermal experiments employing six commercial IL columns were conducted at different temperatures. On the basis of the temperature-dependent linear solvation energy relationship (LSER) concept, SLB-IL111 exhibited the greatest thermal sensitivity and degree of difference over the tested temperature (T) range, so it was selected for investigation of the 1-phase-GC × GC mode. With the same temperature program, a significantly high degree of orthogonality was observed for the experiment, varied with column lengths. The switchable separation result, which inverts the retention of saturated and unsaturated FAME on the downstream column ((2)D), was achieved by varying column diameters and surface thicknesses of the IL-coated layers. These results were explained according to the corresponding LSER principles. Also, the time summation model was applied for the simulation of the observed 1-phase-GC × GC results.
Publisher: American Chemical Society (ACS)
Date: 18-12-2020
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.ACA.2013.07.002
Abstract: Due to their distinct chemical properties, the application of ionic liquid (IL) compounds as gas chromatography (GC) stationary phases offer unique GC separation especially in the analysis of geometric and positional fatty acid methyl ester (FAME) isomers. Elution behaviour of FAME on several commercialised IL capillary columns including phosphonium based SLB-IL59, SLB-IL60, SLB-IL61 and SLB-IL76 and imidazolium based SLB-IL82, SLB-IL100, and SLB-IL111 as well as a general purpose column SLB-5ms, were evaluated in gas chromatography-mass spectrometry (GC-MS) analysis. The phases were further characterised by using a linear solvation energy relationship (LSER) approach according to the equivalent chain length (ECL) index of FAME. Among all tested IL columns, elution temperatures of saturated FAME increased as their McReynolds' polarity value decreased, except for IL60. ECL values increased markedly as the stationary phase polarity increased, particularly for the polyunsaturated FAME. The LSER study indicated a lowest l/e value at 0.864 for IL111, displaying phase selectivity towards unsaturated FAME, with higher peak capacity within a carbon number isomer group. s and e descriptors calculated from LSER were validated by excellent correlation with dipole moments and lowest unoccupied molecular orbital (LUMO) energies, with R(2) values of 0.99 and 0.92 respectively, calculated using GAUSSIAN.
Publisher: Elsevier BV
Date: 09-2018
Publisher: Elsevier BV
Date: 12-2019
DOI: 10.1016/J.CHROMA.2019.460392
Abstract: Approaches to simulate peak time and intensity profiles of compounds in comprehensive two dimensional gas chromatography (GC × GC) were developed, and which are demonstrated for separation of a mixture of saturated and unsaturated fatty acid methyl esters (FAME) using a range of column sets. The simulation of first and second dimension time (
Publisher: Wiley
Date: 11-2014
Publisher: American Chemical Society (ACS)
Date: 22-03-2016
DOI: 10.1021/ACS.ANALCHEM.5B03839
Abstract: Recent advances in multidimensional gas chromatography (MDGC) comprise methods such as multiple heart-cut (H/C) analysis and comprehensive two-dimensional gas chromatography (GC × GC) however, clear approaches to evaluate the MDGC results, choice of the most appropriate method, and optimized separation remain of concern. In order to track the capability of these analytical techniques and select an effective experimental approach, a fundamental approach was developed utilizing a time summation model incorporating temperature-dependent linear solvation energy relationship (LSER). The approach allows prediction of optimized analyte distribution in the 2D space for various MDGC approaches employing different experimental variables such as column lengths, temperature programs, and stationary phase combinations in order to evaluate separation performance (apparent (1)D, (2)D, total number of separated peaks, and orthogonality) for simulated MDGC results. The methodology applied LSER to generate results for nonpolar-polar and polar-nonpolar 2D column configurations for separation of 678 compounds in an oxidized kerosene-based jet fuel s le. Three-dimensional plots were generated in order to illustrate the dependency of separation performance on (2)D column length and number of injections for different stationary phase combinations. With a given limit of analysis time, a MDGC approach to obtain an optimized total separated peak number for a particular column set was proposed depending on (1)D and (2)D analyte peak distribution. This study introduces fundamental concepts and establishes approaches to design effective GC × GC or multiple H/C systems for different column combinations, to provide the best overall separation outcomes with the highest separated peak number and/or orthogonality.
Publisher: Wiley
Date: 25-07-2014
Abstract: Effective separation of mixtures of enantiomers is of continuing interest in analytical and preparative chromatography, with new materials frequently designed and tested. We report two new enantiomerically pure 2D→3D interpenetrated materials used as stationary liquid chromatographic (LC) phases that are shown to resolve selected racemic mixtures with enantiomeric and chemical selectivity. Dicarboxylate ligands derived from amino acids on naphthalene and perylene cores form 2D frameworks that interpenetrate to give 3D structures. Selectivity is initially tested by uptake from solution subsequent LC methods show that the materials exhibit resolution of racemic analytes in 'micro-columns' and that the two closely related materials show markedly different selectivity for different analytes with much greater activity than the ligands alone. Comparison with a close-packed analogue suggests that the separation activity is largely due to surface effects.
Publisher: Elsevier BV
Date: 05-2021
Publisher: American Chemical Society (ACS)
Date: 10-01-2023
Publisher: Elsevier BV
Date: 04-2018
DOI: 10.1016/J.CHROMA.2018.02.035
Abstract: Real-time interconversion processes produce unconventional peak broadening in gas chromatography (GC), and can be used to generate kinetic and thermodynamic data. In this study, an unusual separation situation in comprehensive two dimensional GC where two dimensional interconversion (i.e. a raised plateau in both first and second dimension,
Publisher: Elsevier BV
Date: 02-2018
Publisher: Wiley
Date: 13-01-2014
DOI: 10.1002/CHIR.22280
Abstract: Chiral comprehensive two-dimensional gas chromatography (eGC×GC) coupled to quadrupole-accurate mass time-of-flight mass spectrometry (QTOFMS) was evaluated for its capability to report the chiral composition of several monoterpenes, namely, α-pinene, β-pinene, and limonene in cardamom oil. Enantiomers in a standard mixture were fully resolved by direct enantiomeric-GC analysis with a 2,3-di-O-methyl-6-t-butylsilyl derivatized β-cyclodextrin phase however, the (+)-(R)-limonene enantiomer in cardamom oil was overlapped with other background components including cymene and cineole. Verification of (+)-(R)-limonene components based on characteristic ions at m/z 136, 121, and 107 acquired by chiral single-dimension GC-QTOFMS in the alternate MS/MSMS mode of operation was unsuccessful due to similar parent/daughter ions generated by interfering or co-eluting cymene and cineole. Column phases SUPELCOWAX, SLB-IL111, HP-88, and SLB-IL59, were incorporated as the second dimension column ((2)D) in chiral GC×GC analysis the SLB-IL59 offered the best resolution for the tested monoterpene enantiomers from the matrix background. Enantiomeric ratios for α-pinene, β-pinene, and limonene were determined to be 1.325, 2.703, and 1.040, respectively, in the cardamom oil s le based on relative peak area data.
Publisher: American Chemical Society (ACS)
Date: 12-08-2020
No related grants have been discovered for Yada Nolvachai.