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Trinklein TJ, Synovec RE. Simulating comprehensive two-dimensional gas chromatography mass spectrometry data with realistic run-to-run shifting to evaluate the robustness of tile-based Fisher ratio analysis. J Chromatogr A 2022; 1677:463321. [PMID: 35853427 DOI: 10.1016/j.chroma.2022.463321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/01/2022] [Accepted: 07/07/2022] [Indexed: 10/17/2022]
Abstract
Untargeted analysis of comprehensive two-dimensional (2D) gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS) data has the potential to be hindered by run-to-run retention time shifting. To address this challenge, tile-based Fisher ratio (F-ratio) analysis (FRA) has been developed, which utilizes a supervised, untargeted approach involving a chromatographic segmentation routine termed "tiling" combined with the ANOVA F-ratio statistic to discover class-distinguishing analytes while minimizing false positives arising from shifting. The tiling algorithm is designed to account for retention shifting in both separation dimensions. Although applications of FRA have been reported, there remains a need to thoroughly evaluate the robustness of FRA for different levels of run-to-run retention shifting in order to broaden the scope of its application. To this end, a novel method of simulating GC×GC-TOFMS chromatograms with realistic run-to-run shifting is presented by random generation of low-frequency "shift functions". The dimensionless retention-time precision, <δr>, which is four times the standard deviation in retention time normalized to the peak width-at-base is used as a key modeling variable along with the 2D chromatographic saturation, αe,2D, and within-class relative standard deviation in peak area, RSDwc. We demonstrate that all three of these variables operate together to impact true positive discovery. To quantify the "success" of true positive discovery, GC×GC-TOFMS datasets for various combinations of <δr>, αe,2D, and RSDwc were simulated and then analyzed by FRA using a wide range of relative tile areas (RTA), which is a dimensionless measure of tile size. Since each hit in the FRA hit list was known a priori as either a true or false positive based on the simulation inputs, receiver operating characteristic (ROC) curves were readily constructed. Then, the area under the ROC curve (AUROC) was used as a metric for discovery "success" for various combinations of the modeling variables. Based on the results of this study, recommendations for tile size selection and experimental design are provided, and further supported by comparison to previous tile-based FRA applications. For instance, values for <δr>, αe,2D, and RSDwc obtained from a GC×GC-TOFMS dataset of yeast metabolites suggested an optimum RTA of 6.25, corresponding closely to the RTA of 4.00 employed in the study, implying the simulation results obtained here can be generalized to real datasets.
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Affiliation(s)
- Timothy J Trinklein
- Department of Chemistry, Box 351700, University of Washington, Seattle, WA 98195, USA
| | - Robert E Synovec
- Department of Chemistry, Box 351700, University of Washington, Seattle, WA 98195, USA.
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Ghosh C, Leon A, Koshy S, Aloum O, Al-Jabawi Y, Ismail N, Weiss ZF, Koo S. Breath-Based Diagnosis of Infectious Diseases: A Review of the Current Landscape. Clin Lab Med 2021; 41:185-202. [PMID: 34020759 DOI: 10.1016/j.cll.2021.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Various analytical methods can be applied to concentrate, separate, and examine trace volatile organic metabolites in the breath, with the potential for noninvasive, rapid, real-time identification of various disease processes, including an array of microbial infections. Although biomarker discovery and validation in microbial infections can be technically challenging, it is an approach that has shown great promise, especially for infections that are particularly difficult to identify with standard culture and molecular amplification-based approaches. This article discusses the current state of breath analysis for the diagnosis of infectious diseases.
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Affiliation(s)
- Chiranjit Ghosh
- Division of Infectious Diseases, Brigham and Women's Hospital, 181 Longwood Avenue, MCP642, Boston, MA 02115, USA; Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA
| | - Armando Leon
- Division of Infectious Diseases, Brigham and Women's Hospital, 181 Longwood Avenue, MCP642, Boston, MA 02115, USA; Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA
| | - Seena Koshy
- Division of Infectious Diseases, Brigham and Women's Hospital, 181 Longwood Avenue, MCP642, Boston, MA 02115, USA; Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA
| | - Obadah Aloum
- Division of Infectious Diseases, Brigham and Women's Hospital, 181 Longwood Avenue, MCP642, Boston, MA 02115, USA; Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA
| | - Yazan Al-Jabawi
- Division of Infectious Diseases, Brigham and Women's Hospital, 181 Longwood Avenue, MCP642, Boston, MA 02115, USA; Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA
| | - Nour Ismail
- Division of Infectious Diseases, Brigham and Women's Hospital, 181 Longwood Avenue, MCP642, Boston, MA 02115, USA; Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA
| | - Zoe Freeman Weiss
- Division of Infectious Diseases, Brigham and Women's Hospital, 181 Longwood Avenue, MCP642, Boston, MA 02115, USA; Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA; Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Sophia Koo
- Division of Infectious Diseases, Brigham and Women's Hospital, 181 Longwood Avenue, MCP642, Boston, MA 02115, USA; Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA; Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA.
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Ahn YG, Jeon SH, Lim HB, Choi NR, Hwang GS, Kim YP, Lee JY. Analysis of Polycyclic Aromatic Hydrocarbons in Ambient Aerosols by Using One-Dimensional and Comprehensive Two-Dimensional Gas Chromatography Combined with Mass Spectrometric Method: A Comparative Study. JOURNAL OF ANALYTICAL METHODS IN CHEMISTRY 2018; 2018:8341630. [PMID: 29805841 PMCID: PMC5901813 DOI: 10.1155/2018/8341630] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 02/06/2018] [Accepted: 02/19/2018] [Indexed: 06/08/2023]
Abstract
Advanced separation technology paired with mass spectrometry is an ideal method for the analysis of atmospheric samples having complex chemical compositions. Due to the huge variety of both natural and anthropogenic sources of organic compounds, simultaneous quantification and identification of organic compounds in aerosol samples represents a demanding analytical challenge. In this regard, comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS) has become an effective analytical method. However, verification and validation approaches to quantify these analytes have not been critically evaluated. We compared the performance of gas chromatography with quadrupole mass spectrometry (GC-qMS) and GC×GC-TOFMS for quantitative analysis of eighteen target polycyclic aromatic hydrocarbons (PAHs). The quantitative obtained results such as limits of detection (LODs), limits of quantification (LOQs), and recoveries of target PAHs were approximately equivalent based on both analytical methods. Furthermore, a larger number of analytes were consistently identified from the aerosol samples by GC×GC-TOFMS compared to GC-qMS. Our findings suggest that GC×GC-TOFMS would be widely applicable to the atmospheric and related sciences with simultaneous target and nontarget analysis in a single run.
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Affiliation(s)
- Yun Gyong Ahn
- Western Seoul Center, Korea Basic Science Institute, Seoul 03759, Republic of Korea
| | - So Hyeon Jeon
- Western Seoul Center, Korea Basic Science Institute, Seoul 03759, Republic of Korea
| | - Hyung Bae Lim
- Air Quality Research Division, National Institute of Environmental Research, Incheon 22689, Republic of Korea
| | - Na Rae Choi
- Department of Environmental Science and Engineering, Ewha Womans University, Seoul 03759, Republic of Korea
| | - Geum-Sook Hwang
- Western Seoul Center, Korea Basic Science Institute, Seoul 03759, Republic of Korea
| | - Yong Pyo Kim
- Department of Chemical Engineering and Material Science, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Ji Yi Lee
- Department of Environmental Science and Engineering, Ewha Womans University, Seoul 03759, Republic of Korea
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5
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Current-day employment of the micro-bore open-tubular capillary column in the gas chromatography field. J Chromatogr A 2012; 1261:23-36. [DOI: 10.1016/j.chroma.2012.05.074] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 05/15/2012] [Accepted: 05/16/2012] [Indexed: 11/24/2022]
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Kim YH, Kim KH. Ultimate detectability of volatile organic compounds: how much further can we reduce their ambient air sample volumes for analysis? Anal Chem 2012; 84:8284-93. [PMID: 22934885 DOI: 10.1021/ac301792x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To understand the ultimately lowest detection range of volatile organic compounds (VOCs) in air, application of a high sensitivity analytical system was investigated by coupling thermal desorption (TD) technique with gas chromatography (GC) and time-of-flight (TOF) mass spectrometry (MS). The performance of the TD-GC/TOF MS system was evaluated using liquid standards of 19 target VOCs prepared in the range of 35 pg to 2.79 ng per μL. Studies were carried out using both total ion chromatogram (TIC) and extracted ion chromatogram (EIC) mode. EIC mode was used for calibration to reduce background and to improve signal-to-noise. The detectability of 19 target VOCs, if assessed in terms of method detection limit (MDL, per US EPA definition) and limit of detection (LOD), averaged 5.90 pg and 0.122 pg, respectively, with the mean coefficient of correlation (R(2)) of 0.9975. The minimum quantifiable mass of target analytes, when determined using real air samples by the TD-GC/TOF MS, is highly comparable to the detection limits determined experimentally by standard. In fact, volumes for the actual detection of the major aromatic VOCs like benzene, toluene, and xylene (BTX) in ambient air samples were as low as 1.0 mL in the 0.11-2.25 ppb range. It was thus possible to demonstrate that most target compounds including those in low abundance could be reliably quantified at concentrations down to 0.1 ppb at sample volumes of less than 10 mL. The unique sensitivity of this advanced analytical system can ultimately lead to a shift in field sampling strategy with smaller air sample volumes facilitating faster, simpler air sampling (e.g., use of gas syringes rather than the relative complexity of pumps or bags/canisters), with greatly reduced risk of analyte breakthrough and minimal interference, e.g., from atmospheric humidity. The improved detection limits offered by this system can also enhance accuracy and measurement precision.
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Affiliation(s)
- Yong-Hyun Kim
- Department of Environment and Energy, Sejong University, Seoul, Korea
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Silva BJG, Tranchida PQ, Purcaro G, Queiroz MEC, Mondello L, Lanças FM. Evaluation of comprehensive two-dimensional gas chromatography coupled to rapid scanning quadrupole mass spectrometry for quantitative analysis. J Chromatogr A 2012; 1255:177-83. [DOI: 10.1016/j.chroma.2012.05.035] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 05/02/2012] [Accepted: 05/03/2012] [Indexed: 11/24/2022]
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Tsugawa H, Bamba T, Shinohara M, Nishiumi S, Yoshida M, Fukusaki E. Practical non-targeted gas chromatography/mass spectrometry-based metabolomics platform for metabolic phenotype analysis. J Biosci Bioeng 2011; 112:292-8. [PMID: 21641865 DOI: 10.1016/j.jbiosc.2011.05.001] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 05/02/2011] [Accepted: 05/02/2011] [Indexed: 11/18/2022]
Abstract
Gas chromatography coupled to mass spectrometry (GC/MS) is a core analytical method for metabolomics and has been used as a platform in non-targeted analysis, especially for hydrophilic metabolites. Non-targeted GC/MS-based metabolomics generally requires a high-throughput technology to handle a large volume of samples and an accumulated database (reference library) of the retention times and mass spectra of standard compounds for accurate peak identification. In this study, we provide a practical GC/MS platform and an auto peak identification technique that is not restricted to certain types of mass spectrometers. The platform utilizes a quadrupole mass spectrometer capable of high-speed scanning, resulting in greater output compared with Pegasus GC-time of flight (TOF)/MS, which has been an essential instrument for high-throughput experiments. Moreover, we show that our reference library is broadly applicable to other instruments; peak identification can be readily performed using the library without constructing a reference resource. The usefulness and versatility of our system are demonstrated by the analyses of three experimental metabolomics data sets, including standard mixtures and real biological samples.
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Affiliation(s)
- Hiroshi Tsugawa
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, Japan
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9
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Accelerating analysis for metabolomics, drugs and their metabolites in biological samples using multidimensional gas chromatography. Bioanalysis 2011; 1:367-91. [PMID: 21083173 DOI: 10.4155/bio.09.28] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Gas chromatography (GC) with mass spectrometry (MS) is one of the great enabling analytical tools available to the chemical and biochemical analyst for the measurement of volatile and semi-volatile compounds. From the analysis result, it is possible to assess progress in chemical reactions, to monitor environmental pollutants in a wide range of soil, water or air samples, to determine if an athlete or horse trainer has contravened doping laws, or if crude oil has migrated through subsurface rock to a reservoir. Each of these scenarios and samples has an associated implementation method for GC-MS. However, few samples and the associated interpretation of data is as complex or important as biochemical sample analysis for trace drugs or metabolites. Improving the analysis in both the GC and MS domains is a continual search for better separation, selectivity and sensitivity. Multidimensional methods are playing important roles in providing quality data to address the needs of analysts.
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Wojtowicz P, Zrostlíková J, Kovalczuk T, Schůrek J, Adam T. Evaluation of comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry for the diagnosis of inherited metabolic disorders using an automated data processing strategy. J Chromatogr A 2010; 1217:8054-61. [DOI: 10.1016/j.chroma.2010.09.067] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Revised: 09/22/2010] [Accepted: 09/23/2010] [Indexed: 11/16/2022]
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Wei LM, Shen Q, Lu HJ, Yang PY. Pretreatment of low-abundance peptides on detonation nanodiamond for direct analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2009; 877:3631-7. [DOI: 10.1016/j.jchromb.2009.09.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Revised: 08/31/2009] [Accepted: 09/02/2009] [Indexed: 10/20/2022]
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12
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Silva A, Pereira H, Casilli A, Conceição F, Aquino Neto F. Analytical challenges in doping control: Comprehensive two-dimensional gas chromatography with time of flight mass spectrometry, a promising option. J Chromatogr A 2009; 1216:2913-22. [DOI: 10.1016/j.chroma.2008.10.042] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2008] [Revised: 09/30/2008] [Accepted: 10/08/2008] [Indexed: 10/21/2022]
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13
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Cordero C, Bicchi C, Galli M, Galli S, Rubiolo P. Evaluation of different internal-diameter column combinations in comprehensive two-dimensional gas chromatography in flavour and fragrance analysis. J Sep Sci 2008; 31:3437-50. [DOI: 10.1002/jssc.200800280] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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14
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Marsman J, Wildschut J, Evers P, de Koning S, Heeres H. Identification and classification of components in flash pyrolysis oil and hydrodeoxygenated oils by two-dimensional gas chromatography and time-of-flight mass spectrometry. J Chromatogr A 2008; 1188:17-25. [DOI: 10.1016/j.chroma.2008.02.034] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Revised: 02/05/2008] [Accepted: 02/07/2008] [Indexed: 10/22/2022]
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15
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Luedemann A, Strassburg K, Erban A, Kopka J. TagFinder for the quantitative analysis of gas chromatography--mass spectrometry (GC-MS)-based metabolite profiling experiments. ACTA ACUST UNITED AC 2008; 24:732-7. [PMID: 18204057 DOI: 10.1093/bioinformatics/btn023] [Citation(s) in RCA: 379] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
MOTIVATION Typical GC-MS-based metabolite profiling experiments may comprise hundreds of chromatogram files, which each contain up to 1000 mass spectral tags (MSTs). MSTs are the characteristic patterns of approximately 25-250 fragment ions and respective isotopomers, which are generated after gas chromatography (GC) by electron impact ionization (EI) of the separated chemical molecules. These fragment ions are subsequently detected by time-of-flight (TOF) mass spectrometry (MS). MSTs of profiling experiments are typically reported as a list of ions, which are characterized by mass, chromatographic retention index (RI) or retention time (RT), and arbitrary abundance. The first two parameters allow the identification, the later the quantification of the represented chemical compounds. Many software tools have been reported for the pre-processing, the so-called curve resolution and deconvolution, of GC-(EI-TOF)-MS files. Pre-processing tools generate numerical data matrices, which contain all aligned MSTs and samples of an experiment. This process, however, is error prone mainly due to (i) the imprecise RI or RT alignment of MSTs and (ii) the high complexity of biological samples. This complexity causes co-elution of compounds and as a consequence non-selective, in other words impure MSTs. The selection and validation of optimal fragment ions for the specific and selective quantification of simultaneously eluting compounds is, therefore, mandatory. Currently validation is performed in most laboratories under human supervision. So far no software tool supports the non-targeted and user-independent quality assessment of the data matrices prior to statistical analysis. TagFinder may fill this gap. STRATEGY TagFinder facilitates the analysis of all fragment ions, which are observed in GC-(EI-TOF)-MS profiling experiments. The non-targeted approach allows the discovery of novel and unexpected compounds. In addition, mass isotopomer resolution is maintained by TagFinder processing. This feature is essential for metabolic flux analyses and highly useful, but not required for metabolite profiling. Whenever possible, TagFinder gives precedence to chemical means of standardization, for example, the use of internal reference compounds for retention time calibration or quantitative standardization. In addition, external standardization is supported for both compound identification and calibration. The workflow of TagFinder comprises, (i) the import of fragment ion data, namely mass, time and arbitrary abundance (intensity), from a chromatography file interchange format or from peak lists provided by other chromatogram pre-processing software, (ii) the annotation of sample information and grouping of samples into classes, (iii) the RI calculation, (iv) the binning of observed fragment ions of equal mass from different chromatograms into RI windows, (v) the combination of these bins, so-called mass tags, into time groups of co-eluting fragment ions, (vi) the test of time groups for intensity correlated mass tags, (vii) the data matrix generation and (viii) the extraction of selective mass tags supported by compound identification. Thus, TagFinder supports both non-targeted fingerprinting analyses and metabolite targeted profiling. AVAILABILITY Exemplary TagFinder workspaces and test data sets are made available upon request to the contact authors. TagFinder is made freely available for academic use from http://www-en.mpimp-golm.mpg.de/03-research/researchGroups/01-dept1/Root_Metabolism/smp/TagFinder/index.html.
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Affiliation(s)
- Alexander Luedemann
- Department Prof. L. Willmitzer, Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, D-14476 Potsdam-Golm, Germany
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Tamakawa K. Chapter 17 Polycyclic Aromatic Hydrocarbons. FOOD CONTAMINANTS AND RESIDUE ANALYSIS 2008. [DOI: 10.1016/s0166-526x(08)00017-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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17
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Portolés T, Pitarch E, López FJ, Sancho JV, Hernández F. Methodical approach for the use of GC-TOF MS for screening and confirmation of organic pollutants in environmental water. JOURNAL OF MASS SPECTROMETRY : JMS 2007; 42:1175-85. [PMID: 17605142 DOI: 10.1002/jms.1248] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The potential of gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF MS) for the screening of organic pollutants in water was explored. After a conventional SPE step with C(18) cartridges, the comparison of spectra with available libraries together with an evaluation of the mass accuracy was the first approach used for the screening and confirmation of target analytes. However, at low analyte concentrations (i.e. below 0.1 microg/l), this procedure was not feasible and the use of the application manager TargetLynx was evaluated. This application allows the selection of up to five representative ions per analyte, measured with high mass accuracy, and their intensity ratio evaluation. Ion selection, extraction mass window and concentration levels were found to be the critical parameters. The reference compound used as 'lock mass' was also found to affect to the quality of information obtained in some particular cases. Full spectral acquisition data generated by the TOF MS analyzer allowed investigation of the presence of several analytes in samples in a post-target style, without the need of reanalyze the water samples.Finally, a methodical approach was established for the reliable screening and confirmation of organic pollutants (PAHs, pesticides, octyl/nonyl phenols) in real-world samples, which led to satisfactory results of approximately 0.1 microg/l.
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Affiliation(s)
- Tania Portolés
- Research Institute for Pesticides and Water, University Jaume I, Castellón, Spain
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18
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Cordero C, Bicchi C, Joulain D, Rubiolo P. Identification, quantitation and method validation for the analysis of suspected allergens in fragrances by comprehensive two-dimensional gas chromatography coupled with quadrupole mass spectrometry and with flame ionization detection. J Chromatogr A 2007; 1150:37-49. [PMID: 16973171 DOI: 10.1016/j.chroma.2006.08.079] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2006] [Revised: 08/24/2006] [Accepted: 08/28/2006] [Indexed: 11/24/2022]
Abstract
The first part of this study first aims at validating a method to identify suspected allergens limited by EU regulations in fragrances by comprehensive two-dimensional gas chromatography (GC x GC) coupled with rapid scanning quadrupole MS (GC x GC-qMS). The effectiveness of the quadrupole MS operating at different scanning speed (1000 and 11,111 amu/s) was evaluated in identifying (full scan mode acquisition--TIC) and in quantifying (single ion monitoring--SIM) the target analytes in complex mixtures. In full scan acquisition mode the mass range was reduced to 40-240 amu to increase the scan acquisition rate while in SIM mode the influence of different dwell-times (40, 10 and 5 ms) was tested. The number of scans for each single modulated chromatographic GC x GC peak and the total number of scans for the 2D peak, together with half height peak width (referred to apex) of each allergen in the standard mixture in both TIC and SIM modes were determined. Moreover, the match quality of the spectra obtained by GC/MS at 1000 and 11,111 amu/s and by GC x GC-MS at 11,111 amu/s were compared and the occurrence of spectral skewing verified. In the second part of this work quantitative methods by GC x GC-SIM/qMS and GC x GC-FID were validated on the basis of Eurachem/CITAC protocols through which the following performance parameters were determined: confirmation of identity, selectivity and specificity, limit of detection (LOD), limit of quantitation (LOQ), linearity (working and linear range), precision and accuracy and uncertainty. Suspected allergens were spiked in a concentration range between 2 and 25 ppm (microg/mL) on a Test fragrance taken as a reference, while 1,4 dibromo-benzene and 4,4'-dibromodiphenyl were used as internal standards.
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Affiliation(s)
- Chiara Cordero
- Dipartimento di Scienza e Tecnologia del Farmaco, Università degli Studi di Torino, Via P. Giuria 9, I-10125 Torino, Italy.
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Donato P, Tranchida PQ, Dugo P, Dugo G, Mondello L. Rapid analysis of food products by means of high speed gas chromatography. J Sep Sci 2007; 30:508-26. [PMID: 17444220 DOI: 10.1002/jssc.200600407] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Since the invention of GC, there has been an ever increasing interest within the chromatographic community for faster GC methods. This is obviously related to the fact that the number of samples subjected to GC analysis has risen greatly. Nowadays, in routine analytical applications, sample throughput is often the most important aspect considered when choosing an analytical method. Gas chromatographic instrumentation, especially in the last decade, has been subjected to continuous and considerable improvement. High-speed injection systems, electronic gas pressure control, rapid oven heating/cooling and fast detection are currently available in a variety of commercial gas chromatographs. The main consequence of this favourable aspect is that high-speed GC is being increasingly employed for routine analysis in different fields. Furthermore, the employment of dedicated software makes the passage from a conventional to a fast GC method a rather simple step. The present review provides an overview of the employment of fast GC techniques for the analysis of food constituents and contaminants. A brief historical and theoretical background is also provided for the approaches described.
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Affiliation(s)
- Paola Donato
- Dipartimento Farmaco-chimico, Facoltà di Farmacia, Università di Messina, viale Annunziata, Messina, Italy
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Hoh E, Mastovska K, Lehotay SJ. Optimization of separation and detection conditions for comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry analysis of polychlorinated dibenzo-p-dioxins and dibenzofurans. J Chromatogr A 2007; 1145:210-21. [PMID: 17306276 DOI: 10.1016/j.chroma.2007.01.064] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Revised: 01/18/2007] [Accepted: 01/22/2007] [Indexed: 10/23/2022]
Abstract
The 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are among the most toxic compounds known, and several sources of exposure to these chemicals should be monitored to protect human and environmental health. The current predominant method of analysis is too expensive and cumbersome, and comprehensive two-dimensional GC coupled to time-of-flight mass spectrometry (GC x GC--TOF-MS) has the potential to lower the costs and speed analysis of PCDD/Fs. In this study, GC x GC--TOF parameters were evaluated and optimized to yield complete separation of the 17 most important PCDD/F congeners from polychlorinated biphenyls (PCBs) interferences, and to attain the lowest detection limits. The optimization study entailed evaluation of oven temperature programs, column flow rates, ion source temperatures, electron ionization energy, data acquisition rate, and various GC x GC parameters, including modulation period, modulator temperature offset and hot pulse duration. After optimization, all 17 PCDD/Fs were separated in <60 min, and in particular, the critical pair of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and pentachlorobiphenyl congener CB126 did not co-elute chromatographically. Accurate identification and determination of all analytes could be made using their deconvoluted full mass spectra. In GC x GC, the modulation period and start time were the most important factors that affected sensitivity and selectivity for the analysis of the PCDD/Fs. The modulation period should be < or = 4s to preserve separations achieved in one-dimensional GC, and the modulation start time was important to achieve one large slice and two smaller symmetrical slices of TCDD to maximize its detection sensitivity. After optimization, the method could identify 0.25 pg of TCDD with standard injection from its full mass spectrum.
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Affiliation(s)
- Eunha Hoh
- US Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
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21
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Williamson LN, Bartlett MG. Quantitative gas chromatography/time-of-flight mass spectrometry: a review. Biomed Chromatogr 2007; 21:664-9. [PMID: 17472219 DOI: 10.1002/bmc.847] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Time-of-flight (TOF) instruments have recently gained popularity in quantitative analyses. Normally, TOF mass spectrometers are used for accurate mass measurements for empirical formula verification. However, over the past decade, they have been used quantitatively as well. Because of the fast separations and narrow peaks that result from gas chromatography separations, scanning mass spectrometers are not ideal detectors. TOF mass spectrometers, however, have the ability to collect spectra at a faster rate. Two-dimensional gas chromatography has also been introduced to further resolve peaks from complex matrices. Two-dimensional gas chromatography results in a faster separation as well as narrower peaks. This paper reviews the methods currently in the literature for the quantitation of compounds using one- and two-dimensional gas chromatography and TOF mass spectrometry detection.
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Affiliation(s)
- Leah N Williamson
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, Athens, GA 30602-2352, USA
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22
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Poster DL, Schantz MM, Sander LC, Wise SA. Analysis of polycyclic aromatic hydrocarbons (PAHs) in environmental samples: a critical review of gas chromatographic (GC) methods. Anal Bioanal Chem 2006; 386:859-81. [PMID: 17019586 DOI: 10.1007/s00216-006-0771-0] [Citation(s) in RCA: 260] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2006] [Revised: 08/04/2006] [Accepted: 08/10/2006] [Indexed: 11/30/2022]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are frequently measured in the atmosphere for air quality assessment, in biological tissues for health-effects monitoring, in sediments and mollusks for environmental monitoring, and in foodstuffs for safety reasons. In contemporary analysis of these complex matrices, gas chromatography (GC), rather than liquid chromatography (LC), is often the preferred approach for separation, identification, and quantification of PAHs, largely because GC generally affords greater selectivity, resolution, and sensitivity than LC. This article reviews modern-day GC and state-of-the-art GC techniques used for the determination of PAHs in environmental samples. Standard test methods are discussed. GC separations of PAHs on a variety of capillary columns are examined, and the properties and uses of selected mass spectrometric (MS) techniques are presented. PAH literature on GC with MS techniques, including chemical ionization, ion-trap MS, time-of-flight MS (TOF-MS), and isotope-ratio mass spectrometry (IRMS), is reviewed. Enhancements to GC, for example large-volume injection, thermal desorption, fast GC, and coupling of GC to LC, are also discussed with regard to the determination of PAHs in an effort to demonstrate the vigor and robustness GC continues to achieve in the analytical sciences.
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Affiliation(s)
- Dianne L Poster
- Analytical Chemistry Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8392, USA.
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23
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Richoll SM, Colón I. Determination of triphenylphosphine oxide in active pharmaceutical ingredients by hollow-fiber liquid-phase microextraction followed by reversed-phase liquid chromatography. J Chromatogr A 2006; 1127:147-53. [PMID: 16814311 DOI: 10.1016/j.chroma.2006.06.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2006] [Revised: 05/26/2006] [Accepted: 06/01/2006] [Indexed: 11/18/2022]
Abstract
A versatile procedure has been developed and validated for the determination of triphenylphosphine oxide (TPPO) at low levels in various active pharmaceutical ingredients (APIs). This procedure incorporates the use of the novel hollow-fiber liquid-phase microextraction (LPME) for the measurement of this potential process-related impurity in aqueous solutions of APIs. A small volume (40 microL) of 1-octanol contained within a hollow polypropylene fiber is used for the extraction of TPPO from low pH aqueous API solutions. More than a 100-fold increase in the TPPO concentration is obtained without additional evaporation of the extract. Experimental parameters of the extraction procedure were investigated to optimize extraction efficiency and minimize sample matrix interference. Using HPLC/UV as the end analysis technique, the procedure was validated for TPPO in the concentration range of 3-16 microg/L with an API present at 1500 mg/L. The versatility of the method was demonstrated by applying the procedure to the analysis of APIs with different molecular structures. This simple LPME procedure is inexpensive and offers appropriate sensitivity for the intended use while providing several advantages over other analysis methods for pharmaceutical samples.
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Affiliation(s)
- Stephen M Richoll
- Analytical R&D, Pfizer Global R&D, Eastern Point Road, Mail Stop 8286-31, Groton, CT 06340, USA.
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24
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Adahchour M, Brandt M, Baier HU, Vreuls RJJ, Batenburg AM, Brinkman UAT. Comprehensive two-dimensional gas chromatography coupled to a rapid-scanning quadrupole mass spectrometer: principles and applications. J Chromatogr A 2005; 1067:245-54. [PMID: 15844530 DOI: 10.1016/j.chroma.2004.09.094] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The principles, practicability and potential of comprehensive two-dimensional (2D) gas chromatography coupled to a rapid-scanning quadrupole mass spectrometer (GC x GC-qMS) for the analysis of complex flavour mixtures in food, allergens in fragrances and polychlorinated biphenyls (PCBs) were studied. With a scan speed of 10,000 amu/s, monitoring over a mass range of up to 200 atomic mass unit (amu) can be achieved at an acquisition frequency of 33 Hz. Extending this mass range and/or increasing the data acquisition frequency results in a loss of spectral quality. Optimal parameter settings allow, next to unambiguous identification/confirmation of target compounds on the basis of high-quality mass spectra, fully satisfactory quantification (three to four modulations per peak) with linear calibration plots and detection limits in the low-pg level. The potential of time-scheduled data acquisition to increase the effective mass range within one GC x GC run was also explored. The analyses, with baseline separation of the flavours, allergens and PCB target compounds, took less than 30 min.
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Affiliation(s)
- Mohamed Adahchour
- Department of Analytical Chemistry and Applied Spectroscopy, Vrije Universiteit, de Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
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25
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Lyapchenko N, Eitner K, Schroeder G, Brzezinski B. The complexes of some s-triazine herbicides with metal cations studied by ESI mass spectrometry and theoretical calculations. J Mol Struct 2004. [DOI: 10.1016/j.molstruc.2003.11.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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26
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Focant JF, Cochran JW, Dimandja JMD, DePauw E, Sjodin A, Turner WE, Patterson DG. High-throughput analysis of human serum for selected polychlorinated biphenyls (PCBs) by gas chromatography-isotope dilution time-of-flight mass spectrometry (GC-IDTOFMS). Analyst 2004; 129:331-6. [PMID: 15042164 DOI: 10.1039/b313675b] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A method for the high-throughput analysis of human serum for the 38 most prevalent polychlorinated biphenyls (PCBs) based on the use of fast gas chromatography-isotopic dilution time-of-flight mass spectrometry (GC-IDTOFMS) is presented. The chromatographic separation time was 8 min. The separation of the congeners was carried out either chromatographically or analytically using the mass spectral deconvolution capability of the TOFMS. The instrument and the method limits of detection (LODs) were 0.5 pg microL(-1) and 20 pg microL(-1), respectively, which is not as good as the one achieved using high resolution mass spectrometry (HRMS) but allows the detection and quantification of the prevalent PCBs present in real human serum samples. The dynamic range covered 3 orders of magnitude. The comparison with the high resolution mass spectrometry (HRMS) reference method (28 min) was good and some separation improvements have been observed. This method allows the analysis of 100 samples per day per instrument.
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Affiliation(s)
- Jean-Francois Focant
- Centers for Disease Control and Prevention, National Center for Environmental Health, Division of Laboratory Sciences, Atlanta, Georgia 30341, USA
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27
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Santos FJ, Galceran MT. Modern developments in gas chromatography-mass spectrometry-based environmental analysis. J Chromatogr A 2003; 1000:125-51. [PMID: 12877169 DOI: 10.1016/s0021-9673(03)00305-4] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Gas chromatography coupled with mass spectrometry (GC-MS) continues to play an important role in the identification and quantification of organic contaminants in environmental samples. GC-MS is one of the most attractive and powerful techniques for routine analysis of some ubiquitous organic pollutants due to its good sensitivity and high selectivity and versatility. This paper presents an overview of recent developments and applications of the GC-MS technique in relation to the analysis in environmental samples of known persistent pollutants and some emerging contaminants. The use of different mass analysers such as linear quadrupole, quadrupole ion-trap, double-focusing sectors and time-of-flight analysers is examined. The advantages and limitations of GC-MS methods for selected applications in the field of environmental analysis are discussed. Recent developments in field-portable GC-MS are also examined.
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Affiliation(s)
- F J Santos
- Departamento de Química Analítica, Universitat de Barcelona, Diagonal 647, Barcelona 08028, Spain
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28
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Dallüge J, Roose P, Brinkman UAT. Evaluation of a high-resolution time-of-flight mass spectrometer for the gas chromatographic determination of selected environmental contaminants. J Chromatogr A 2002; 970:213-23. [PMID: 12350095 DOI: 10.1016/s0021-9673(02)00233-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A benchtop high-resolution time-of-flight mass spectrometer (TOF MS) was evaluated for the determination of key organic microcontaminants. The major advantage of the TOF MS proved to be the high mass resolution of about 0.002 Da (10 ppm). Consequently, the detectability of polar pesticides, polynuclear aromatic hydrocarbons and polychlorinated biphenyls is excellent, and detection limits are in the order of 1-4 pg injected mass. Best mass spectral resolution was obtained for medium-scale peaks. It is a disadvantage that the calibration range is rather limited, viz. to about two orders of magnitude. The high mass spectral resolution was especially useful to improve the selectivity and sensitivity when analyzing target compounds in complex samples and to prevent false-positive identifications.
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Affiliation(s)
- Jens Dallüge
- Free University, Department of Analytical Chemistry and Applied Spectroscopy, Amsterdam, The Netherlands.
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29
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Geerdink RB, Niessen WMA, Brinkman UAT. Trace-level determination of pesticides in water by means of liquid and gas chromatography. J Chromatogr A 2002; 970:65-93. [PMID: 12350103 DOI: 10.1016/s0021-9673(02)00234-0] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The trace-level determination of pesticides and their transformation products (TPs) in water by means of liquid and gas chromatography (LC and GC) is reviewed. Special attention is given to the use of (tandem) mass spectrometry for identification and confirmation purposes. The complementarity of LC- and GC-based techniques and the potential of comprehensive GCXGC are discussed, and also the impressive performance of time-of-flight mass spectrometry. It is also indicated that, in the near future, the TPs rather than the parent compounds should receive most attention--with a better understanding of matrix effects and eluent composition on the ionization efficiency of analytes being urgently required. Finally, the merits of using much shorter LC columns, or even no column at all (flow-injection analysis) in target analysis are shown, and a more cost-efficient and sophisticated strategy for monitoring programmes is briefly introduced.
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Affiliation(s)
- R B Geerdink
- Institute for Inland Water Management and Waste Water Treatment, RIZA, Lelystad, The Netherlands
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30
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Dallüge J, van Rijn M, Beens J, Vreuls RJJ, Brinkman UAT. Comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometric detection applied to the determination of pesticides in food extracts. J Chromatogr A 2002; 965:207-17. [PMID: 12236526 DOI: 10.1016/s0021-9673(01)01324-3] [Citation(s) in RCA: 171] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The separation provided by conventional gas chromatography (1D-GC) can be significantly enhanced by using comprehensive two-dimensional GC (GC X GC) instead. Combination with mass spectrometric detection is desirable for unambiguous confirmation of target compounds and the provisional identification of unknowns. A GC X GC system using a cryogenic modulator was coupled to a time-of-flight mass spectrometric (TOF MS) detector. With the determination of pesticides in vegetable extracts as an example, it was demonstrated that GC X GC improves the separation dramatically. All 58 pesticides of interest could be identified using their full-scan mass spectra, which was not possible when using ID-GC-TOF MS. In addition, the high scan speed of the TOF MS allowed the deconvolution of compounds partly co-eluting in GC X GC.
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31
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Dallüge J, Vreuls RJJ, van Iperen DJ, van Rijn M, Brinkman UAT. Resistively heated gas chromatography coupled to quadrupole mass spectrometry. J Sep Sci 2002. [DOI: 10.1002/1615-9314(20020601)25:9<608::aid-jssc608>3.0.co;2-r] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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32
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Dallüge J, Vreuls RJJ, Beens J, Brinkman UAT. Optimization and characterization of comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometric detection (GC×GC-TOF MS). J Sep Sci 2002. [DOI: 10.1002/1615-9314(20020301)25:4<201::aid-jssc201>3.0.co;2-b] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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