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Kawashima H. Stable Carbon Isotope Ratio of Volatile Organic Compounds in Air Using Solid-Phase Microextraction Coupled with Chromatography, Combustion, and Isotope Ratio Mass Spectrometry. Chromatographia 2022. [DOI: 10.1007/s10337-022-04203-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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2
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Compound Specific Stable Isotope Analysis of Aromatics in Diesel Fuel to Identify Potential Cocktailing. Forensic Sci Int 2022; 334:111244. [DOI: 10.1016/j.forsciint.2022.111244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 01/28/2022] [Accepted: 02/27/2022] [Indexed: 11/24/2022]
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3
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Felix JD, Thomas R, Casas M, Shimizu MS, Avery GB, Kieber RJ, Mead RN, Lane CS, Willey JD, Guy A, Campos MLAM. Compound-Specific Carbon Isotopic Composition of Ethanol in Brazil and US Vehicle Emissions and Wet Deposition. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:1698-1705. [PMID: 30566835 DOI: 10.1021/acs.est.8b05325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Global atmospheric ethanol budget models include large uncertainties in the magnitude of ethanol emission sources and sinks. To apply stable isotope techniques to constrain ethanol emission sources, a headspace solid phase microextraction gas chromatograph-combustion-isotope ratio mass spectrometry method (HS-SPME-GC-C-IRMS) was developed to measure the carbon isotopic composition of aqueous phase ethanol at natural abundance levels (1-30 μM) with a precision of 0.4‰. The method was applied to determine the carbon isotope signatures (δ13C) of vehicle ethanol emission sources in Brazil (-12.8 ± 2.4‰) and the US (-9.8 ± 2.5‰), and to measure the carbon isotope composition of ethanol in wet deposition (-22.6 to -12.7‰). A two end-member isotope mixing model was developed using anthropogenic and biogenic end members and fractionation scenarios to estimate ethanol source contributions to wet deposition collected in Brazil and US. Mixing model results indicate anthropogenic sources contribute two and a half to four times more ethanol to the atmosphere than previously predicted in modeled global ethanol inventories. As established and developing countries continue to rapidly increase ethanol fuel consumption and subsequent emissions, understanding the magnitude of all ethanol sources and sinks will be essential for modeling future atmospheric chemistry and air quality impacts.
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Affiliation(s)
- J David Felix
- Department of Physical and Environmental Science , Texas A&M University-Corpus Christi , Corpus Christi , Texas , 78412 , United States
| | - Rachel Thomas
- Department of Chemistry and Biochemistry , University of North Carolina Wilmington , Wilmington , North Carolina , 28403 , United States
| | - Matt Casas
- Department of Chemistry and Biochemistry , University of North Carolina Wilmington , Wilmington , North Carolina , 28403 , United States
| | - Megumi S Shimizu
- Department of Chemistry and Biochemistry , University of North Carolina Wilmington , Wilmington , North Carolina , 28403 , United States
| | - G Brooks Avery
- Department of Chemistry and Biochemistry , University of North Carolina Wilmington , Wilmington , North Carolina , 28403 , United States
| | - Robert J Kieber
- Department of Chemistry and Biochemistry , University of North Carolina Wilmington , Wilmington , North Carolina , 28403 , United States
| | - Ralph N Mead
- Department of Chemistry and Biochemistry , University of North Carolina Wilmington , Wilmington , North Carolina , 28403 , United States
| | - Chad S Lane
- Department of Earth and Ocean Sciences , University of North Carolina Wilmington , Wilmington , North Carolina , 28403 , United States
| | - Joan D Willey
- Department of Chemistry and Biochemistry , University of North Carolina Wilmington , Wilmington , North Carolina , 28403 , United States
| | - Amanda Guy
- Department of Chemistry and Biochemistry , University of North Carolina Wilmington , Wilmington , North Carolina , 28403 , United States
| | - M Lucia A M Campos
- Departamento de Química, Faculdade de Filosofia, Ciencias e Letras de Ribeirão Preto , Universidade de São Paulo , Avenida dos Bandeirantes 3900 , 14040-901 Ribeirão Preto , São Paulo Brazil
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Blessing M, Jochmann MA, Haderlein SB, Schmidt TC. Optimization of a large-volume injection method for compound-specific isotope analysis of polycyclic aromatic compounds at trace concentrations. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2015; 29:2349-2360. [PMID: 26563706 DOI: 10.1002/rcm.7389] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 09/02/2015] [Accepted: 09/07/2015] [Indexed: 06/05/2023]
Abstract
RATIONALE Compound-specific isotope analysis (CSIA) of persistent organic contaminants can be used for source apportioning in the environment if appropriate sensitivity can be achieved. This paper describes the optimization and validation of a sensitive analytical approach for the determination of the carbon isotope composition of semi-volatile organic compounds, such as polycyclic aromatic hydrocarbons (PAHs). METHODS Analyses are based on the introduction of up to 150 μL of organic extracts by means of programmed temperature vaporization-large-volume injection combined with gas chromatography coupled to isotope ratio mass spectrometry (PTV-LVI-GC/IRMS). To allow for the analysis of more volatile, low-molecular-weight PAHs, the PTV injector was equipped with a sub-ambient/cryogenic cooling. Accuracy, precision, linearity and determination limits for application in isotope analysis were evaluated for a set of individual PAHs ranging from two- to five-ring molecular structures. The method was exemplified by determining the δ(13) C values of individual PAHs in soil samples in a source apportionment study at a contaminated site. RESULTS The choice of PTV injection parameters is crucial to prevent isotope fractionation during injection and largely depends on the analytes to be determined. The observed isotope fractionation effect on semi-volatiles depends on the applied solvent and injection temperature and demonstrates the importance of performing appropriate tests with given PTV parameters for each of the compounds of interest. The proposed PTV-LVI-GC/IRMS method allows the carbon isotope ratio (δ(13) C value) of individual PAHs to be determined accurately and precisely at concentrations of 0.04-0.1 ng μL(-1) even for volatile PAHs such as naphthalene or acenaphthene. CONCLUSIONS LVI with PTV injector cooling allows for the isotopic analysis of volatile and semi-volatile PAHs at trace concentrations, thus considerably expanding the applicability of CSIA in environmental studies.
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Affiliation(s)
- Michaela Blessing
- BRGM, LAB/ISO, 3 avenue Claude Guillemin, BP 36009, F-45060, Orléans cedex 2, France
| | - Maik A Jochmann
- Instrumental Analytical Chemistry, University Duisburg-Essen, Universitätsstr. 5, D-45141, Essen, Germany
| | - Stefan B Haderlein
- Center for Applied Geoscience (ZAG), Eberhard Karls University Tübingen, Hölderlinstr. 12, D-72076, Tübingen, Germany
| | - Torsten C Schmidt
- Instrumental Analytical Chemistry, University Duisburg-Essen, Universitätsstr. 5, D-45141, Essen, Germany
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Herrero-Martín S, Nijenhuis I, Richnow HH, Gehre M. Coupling of a Headspace Autosampler with a Programmed Temperature Vaporizer for Stable Carbon and Hydrogen Isotope Analysis of Volatile Organic Compounds at Microgram per Liter Concentrations. Anal Chem 2015; 87:951-9. [DOI: 10.1021/ac503229e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sara Herrero-Martín
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research, Permoserstrasse 15, D-04318 Leipzig, Germany
| | - Ivonne Nijenhuis
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research, Permoserstrasse 15, D-04318 Leipzig, Germany
| | - Hans H. Richnow
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research, Permoserstrasse 15, D-04318 Leipzig, Germany
| | - Matthias Gehre
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research, Permoserstrasse 15, D-04318 Leipzig, Germany
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6
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Lee X, Zhang L, Huang D, An N, Yang F, Jiang W, Fang B. Analysis of the stable carbon isotope composition of formic and acetic acids. Anal Biochem 2013; 436:178-86. [DOI: 10.1016/j.ab.2013.01.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 01/17/2013] [Accepted: 01/28/2013] [Indexed: 10/27/2022]
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Lee X, Huang D, Lou D, Pawliszyn J. Needle trap extraction for GC analysis of formic and acetic acids in aqueous solution. J Sep Sci 2012; 35:1675-981. [DOI: 10.1002/jssc.201101082] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Xinqing Lee
- State Key Laboratory of Environmental Geochemistry; Institute of Geochemistry; Chinese Academy of Sciences; Guiyang China
| | - Daikuan Huang
- State Key Laboratory of Environmental Geochemistry; Institute of Geochemistry; Chinese Academy of Sciences; Guiyang China
| | - Dawei Lou
- Department of Chemistry; University of Waterloo; Waterloo Ontario Canada
| | - Janusz Pawliszyn
- Department of Chemistry; Jilin Institute of Chemical Technology; Jilin China
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Hattori R, Yamada K, Kikuchi M, Hirano S, Yoshida N. Intramolecular carbon isotope distribution of acetic acid in vinegar. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2011; 59:9049-9053. [PMID: 21830825 DOI: 10.1021/jf200227e] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Compound-specific carbon isotope analysis of acetic acid is useful for origin discrimination and quality control of vinegar. Intramolecular carbon isotope distributions, which are each carbon isotope ratios of the methyl and carboxyl carbons in the acetic acid molecule, may be required to obtain more detailed information to discriminate such origin. In this study, improved gas chromatography-pyrolysis-gas chromatography-combustion-isotope ratio mass spectrometry (GC-Py-GC-C-IRMS) combined with headspace solid-phase microextraction (HS-SPME) was used to measure the intramolecular carbon isotope distributions of acetic acid in 14 Japanese vinegars. The results demonstrated that the methyl carbons of acetic acid molecules in vinegars produced from plants were mostly isotopically depleted in (13)C relative to the carboxyl carbon. Moreover, isotopic differences (δ(13)C(carboxyl) - δ(13)C(methyl)) had a wide range from -0.3 to 18.2‰, and these values differed among botanical origins, C3, C4, and CAM plants.
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Affiliation(s)
- Ryota Hattori
- Central Laboratories for Frontier Technology, Center for Food Safety Science, Kirin Holdings Co. Ltd., 1-13-5 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan.
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Yamada K, Hattori R, Ito Y, Shibata H, Yoshida N. Determination of carbon isotope ratios of methanol and acetaldehyde in air samples by gas chromatography-isotope ratio mass spectrometry combined with headspace solid-phase microextraction. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2010; 46:392-399. [PMID: 20686990 DOI: 10.1080/10256016.2010.505686] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Isotopic signatures of atmospheric methanol and acetaldehyde have the potential to improve our ability to quantitatively assess their importance in atmospheric chemistry. However, isotopic measurements of atmospheric methanol and acetaldehyde and their individual source and sink processes have been limited. In this study, we examined gas chromatography-isotope ratio mass spectrometry combined with headspace solid-phase microextraction to measure the carbon isotope ratios of methanol and acetaldehyde in air samples. The method enabled us to determine carbon isotope ratios with a precision (1 standard deviation) of ± 0.6 ‰ for 20 ml of air sample containing more than 3 ppm of methanol and ± 0.7 ‰ for 20 ml of air sample containing more than 2 ppm of acetaldehyde. Moreover, the applicability of this method to determine isotope ratios of methanol and acetaldehyde emitted from detached plant leaves was demonstrated.
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Affiliation(s)
- Keita Yamada
- Department of Environmental Chemistry and Engineering, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yokohama, Japan.
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Hattori R, Yamada K, Shibata H, Hirano S, Tajima O, Yoshida N. Measurement of the isotope ratio of acetic acid in vinegar by HS-SPME-GC-TC/C-IRMS. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:7115-7118. [PMID: 20504023 DOI: 10.1021/jf100406y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Acetic acid is the main ingredient of vinegar, and the worth of vinegar often depends on the fermentation of raw materials. In this study, we have developed a simple and rapid method for discriminating the fermentation of the raw materials of vinegar by measuring the hydrogen and carbon isotope ratio of acetic acid using head space solid-phase microextraction (HS-SPME) combined with gas chromatography-high temperature conversion or combustion-isotope ratio mass spectrometry (GC-TC/C-IRMS). The measurement of acetic acid in vinegar by this method was possible with repeatabilities (1sigma) of +/-5.0 per thousand for hydrogen and +/-0.4 per thousand for carbon, which are sufficient to discriminate the origin of acetic acid. The fermentation of raw materials of several vinegars was evaluated by this method.
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Affiliation(s)
- Ryota Hattori
- Central Laboratories for Frontier Technology, Center for Food Safety Science, Kirin Holdings Co. Ltd., Kanazawa-ku, Yokohama, Japan.
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Efficiency of monolaurin in mitigating ruminal methanogenesis and modifying C-isotope fractionation when incubating diets composed of either C3 or C4 plants in a rumen simulation technique (Rusitec) system. Br J Nutr 2009; 102:1308-17. [PMID: 19505345 DOI: 10.1017/s0007114509990262] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Mitigation of methanogenesis in ruminants has been an important goal for several decades. Free lauric acid, known to suppress ruminal methanogenesis, has a low palatability; therefore, in the present study the aim was to evaluate the mitigation efficacy of its esterified form (monolaurin). Further, 13C-isotope abundance (delta13C) and 13C-12C fractionation during methanogenesis and fermentation were determined to evaluate possible microbial C-isotope preferences. Using the rumen simulation technique, four basal diets, characterised either by the C3 plants grass (hay) and wheat (straw and grain), or the C4 plant (13C excess compared with C3 plants) maize (straw and grain), and a mixture of the latter two, were incubated with and without monolaurin (50 g/kg dietary DM). Added to hay, monolaurin did not significantly affect methanogenesis. When added to the other diets (P < 0.05 for the wheat-based diet) methane formation was lowered. Monolaurin decreased fibre disappearance (least effect with the hay diet), acetate:propionate ratio, and protozoal counts. Feed residues and SCFA showed the same delta13C as the diets. Methane was depleted in 13C while CO2 was enriched in 13C compared with the diets. Monolaurin addition resulted in 13C depletion of CO2 and enrichment in CH4 (the latter only in the hay diet). In conclusion, monolaurin proved to effectively decrease methanogenesis in the straw-grain diets although this effect might partly be explained by the concomitantly reduced fibre disappearance. The influence on 13C-isotope abundance and fractionation supports the hypothesis that ruminal microbes seem to differentiate to some extent between C-isotopes during methanogenesis and fermentation.
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Medeiros PM, Simoneit BRT. Gas chromatography coupled to mass spectrometry for analyses of organic compounds and biomarkers as tracers for geological, environmental, and forensic research. J Sep Sci 2007; 30:1516-36. [PMID: 17623433 DOI: 10.1002/jssc.200600399] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Gas chromatography, especially when coupled with mass spectrometry, is the analytical method of choice for elucidation of biomarker compounds present in organic mixtures extracted from geological, environmental, and biological samples. This review describes the biomarker concept, i. e., the precursor natural products to the geological/environmental derivatives, and their application as multi-tracers in the geosphere and ambient environment. The mass spectrometric methods currently utilized for such analyses are reviewed with a general key to the literature, and typical examples of applications using GC-MS are also described.
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Affiliation(s)
- Patricia M Medeiros
- Environmental and Petroleum Research Group, College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, USA
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Moran JJ, House CH, Thomas B, Freeman KH. Products of trace methane oxidation during nonmethyltrophic growth byMethanosarcina. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006jg000268] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
Instrumentation and methods exist for highly precise analyses of the stable-isotopic composition of organic compounds separated by GC. The general approach combines a conventional GC, a chemical reaction interface, and a specialized isotope-ratio mass spectrometer (IRMS). Most existing GC hardware and methods are amenable to isotope-ratio detection. The interface continuously and quantitatively converts all organic matter, including column bleed, to a common molecular form for isotopic measurement. C and N are analyzed as CO2 and N2, respectively, derived from combustion of analytes. H and O are analyzed as H2 and CO produced by pyrolysis/reduction. IRMS instruments are optimized to provide intense, highly stable ion beams, with extremely high precision realized via a system of differential measurements in which ion currents for all major isotopologs are simultaneously monitored. Calibration to an internationally recognized scale is achieved through comparison of closely spaced sample and standard peaks. Such systems are capable of measuring 13C/12C ratios with a precision approaching 0.1 per thousand (for values reported in the standard delta notation), four orders of magnitude better than that typically achieved by conventional "organic" mass spectrometers. Detection limits to achieve this level of precision are typically < 1 nmol C (roughly 10 ng of a typical hydrocarbon) injected on-column. Achievable precision and detection limits are correspondingly higher for N, O, and H, in that order.
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Affiliation(s)
- Alex L Sessions
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA.
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Jochmann MA, Blessing M, Haderlein SB, Schmidt TC. A new approach to determine method detection limits for compound-specific isotope analysis of volatile organic compounds. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2006; 20:3639-48. [PMID: 17103491 DOI: 10.1002/rcm.2784] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Compound-specific isotope analysis (CSIA) has been established as a useful tool in the field of environmental science, in particular in the assessment of contaminated sites. What limits the use of gas chromatography/isotope ratio mass spectrometry (GC/IRMS) is the low sensitivity of the method compared with GC/MS analysis; however, the development of suitable extraction and enrichment techniques for important groundwater contaminants will extend the fields of application for GC/IRMS. So far, purge and trap (P&T) is the most effective, known preconcentration technique for on-line CSIA with the lowest reported method detection limits (MDLs in the low microg/L range). With the goal of improving the sensitivity of a fully automated GC/IRMS analysis method, a commercially available P&T system was modified. The method was evaluated for ten monoaromatic compounds (benzene, toluene, para-xylene, ethylbenzene, propylbenzene, isopropylbenzene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, fluorobenzene) and ten halogenated volatile organic compounds (VOCs) (dichloromethane, cis-1,2-dichloroethene, trans-1,2-dichloroethene, carbon tetrachloride, chloroform, 1,2-dichloroethane, trichloroethene, tetrachlorethene, 1,2-dibromoethane, bromoform). The influence of method parameters, including purge gas flow rates and purge times, on delta13C values of target compounds was evaluated. The P&T method showed good reproducibility, high linearity and small isotopic fractionation. MDLs were determined by consecutive calculation of the delta13C mean values. The last concentration for which the delta13C value was within this iterative interval and for which the standard deviation was lower than +/-0.5 per thousand for triplicate measurements was defined as the MDL. MDLs for monoaromatic compounds between 0.07 and 0.35 microg/L are the lowest values reported so far for continuous-flow isotope ratio measurements using an automated system. MDLs for halogenated hydrocarbons were between 0.76 and 27 microg/L. The environmental applicability of the P&T-GC/IRMS method in the low-microg/L range was demonstrated in a case study on groundwater samples from a former military air field contaminated with VOCs.
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Affiliation(s)
- Maik A Jochmann
- Center for Applied Geoscience (ZAG), Eberhard Karls University Tuebingen, Sigwartstr. 10, 72076 Tuebingen, Germany
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Ferchaud-Roucher V, Albert C, Champ M, Krempf M. Solid-phase microextraction method for carbon isotopic analysis of volatile carboxylic acids in human plasma by gas chromatography/combustion/isotope ratio mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2006; 20:3573-8. [PMID: 17083131 DOI: 10.1002/rcm.2769] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
A new analytical method is described for the determination of the physiological concentration and low-level enrichment of (13)C-short-chain volatile organic acids (SCVAs) (e.g. (13)C-acetate and (13)C-butyrate) in human plasma. This two-step method involves solid-phase microextraction (SPME) coupled to gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) without any organic solvents or derivatizing agents. Two SCVA extraction methods were compared using a carboxen/polydimethylsiloxane fiber: headspace sampling (HS) and liquid sampling (LS) SPME. The influences of extraction temperature and time were tested to optimize the adsorption of SCVAs onto the fiber. The comparison of the peak area responses of the acids in the two adsorption methods showed better sensitivity in the human physiological concentration range in the LS mode than in the HS mode. The accuracy of isotopic enrichment measurement was determined using plasma spiked with (13)C-acetate and (13)C-butyrate solution from 0 to 1 mol percent excess (MPE). The linearity and repeatability (RSD < 5%) were measured in LS mode. Plasma SCVA concentrations were also determined relative to 3-methylvalerate (internal standard). Linearity and repeatability were observed from 0 to 400 microM for acetate, from 0 to 20 microM for propionate, and from 0 to 10 microM for butyrate. This method was also used to determine plasma acetate production obtained from lactulose (an undigestible disaccharide) fermentation in one healthy volunteer over 3 h. The acetate concentration increased twofold, 2 h after oral lactulose intake. These results are in agreement with the data obtained by GC/MS in healthy volunteers and obese adults following a lactulose intake by using higher amounts of labelled tracers.SPME coupled with GC/C/IRMS can be used to analyze (13)C-SCVAs at low enrichment (<0.5 MPE) within the physiological concentration measured in human plasma.
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Chou CC, Lee MR. Determination of organotin compounds in water by headspace solid phase microextraction with gas chromatography–mass spectrometry. J Chromatogr A 2005; 1064:1-8. [PMID: 15729814 DOI: 10.1016/j.chroma.2004.08.166] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This investigation evaluates headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) to determine trace levels of organotins in water. The organotins were derivatized in situ with sodium tetraethylborate and adsorbed on a poly(dimethysiloxane) (PDMS)-coated fused silica fiber. The SPME experimental procedures to extract organotins in water were at pH 5, with extraction and derivatization simultaneously at 45 degrees C for 30 min in a 2% sodium tetraethylborate solution and a sample solution volume in the ratio of 1:1, and desorption in the splitless injection port of the GC at 260 degrees C for 2 min. Detection limits are determined to be in the low ng/L range. According to the analysis, the linearity range is from 10 to 10,000 ng/L with R.S.D. values below 12% except triphenyltin (24%). The proposed method was tested by analyzing surface seawater from the harbors on the Taiwanese coast for organotins residues. Some organotins studied were detected in the analyzed samples. Results of this study demonstrate the adequacy of the headspace SPME-GC-MS method for analyzing organotins in sea water samples.
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Affiliation(s)
- Chi-Chi Chou
- Department of Chemistry, National Chung-Hsing University Taichung, Taiwan, ROC
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Zwank L, Berg M, Schmidt TC, Haderlein SB. Compound-specific carbon isotope analysis of volatile organic compounds in the low-microgram per liter range. Anal Chem 2004; 75:5575-83. [PMID: 14710841 DOI: 10.1021/ac034230i] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Compound-specific carbon isotope analysis (CSIA) has become an important tool in biological, archeological, and geological studies as well as in forensics, food sciences, and organic chemistry. If sensitivity could be enhanced, CSIA would further have an improved potential for environmental applications such as, for example, in situ remediation studies to assess contaminated environments, identification of pollutant degradation pathways and kinetics, distinction between degradation/formation mechanisms, or, verification of contaminant sources. With this goal in mind, we have developed methods to determine delta13C values of commonly reported groundwater contaminants in low-microgram per liter concentrations. Several injection and preconcentration techniques were evaluated for this purpose, i.e., on-column injection, split/ splitless injection, solid-phase microextraction (SPME), and purge and trap (P&T) in combination with gas chromatography-isotope ratio mass spectrometry. The delta13C values of the target compounds were determined by liquid injections of the analytes dissolved in diethyl ether or, in the case of P&T and SPME, by extraction from water spiked with the analytes. P&T extraction was the most efficient preconcentration technique reaching method detection limits (MDLs) from 0.25 to 5.0 microg/L. These are the lowest MDLs reported so far for continuous-flow isotope ratio determinations, using a commercially available and fully automated system. Isotopic fractionation resulting from preconcentration and injection was investigated and quantified for the priority groundwater pollutants methyl tert-butyl ether (MTBE), chloroform, tetrachloromethane, chlorinated ethylenes, benzene, and toluene. The isotopic fractionations caused by the extraction techniques were small but highly reproducible and could therefore be corrected for. P&T was characterized by a higher reproducibility and smaller isotopic fractionations than SPME. Among the liquid injection techniques, cold on-column injection resulted in slightly better precision compared to split/splitless injection. However, the MDLs determined for liquid injections were 4-6 orders of magnitude higher (i.e., 9.5-2800 mg/L) than for P&T and SPME. Since both of the latter methods are solventless, a better chromatographic resolution was obtained than for the liquid injection techniques. The P&T and SPME methods described here are also applicable for CSIA of D/H ratios, which require 10-20 times higher analyte concentrations than 13C/12C analysis. Finally, the applicability of the described methods is demonstrated for pollutant concentrations of only 5-60 microg/L in environmental samples.
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Affiliation(s)
- Luc Zwank
- Swiss Federal Institute for Environmental Science and Technology (EA WAG), Ueberlandstrasse 133, CH-8600 Duebendorf, Switzerland
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Goldstein AH, Shaw SL. Isotopes of Volatile Organic Compounds: An Emerging Approach for Studying Atmospheric Budgets and Chemistry. Chem Rev 2003; 103:5025-48. [PMID: 14664642 DOI: 10.1021/cr0206566] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Allen H Goldstein
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720, USA.
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Norlin E, Irgum K, Ohlsson KEA. Nitrogen isotope analysis of ammonium in aqueous solutions using a perfluorosulfonated ionomer membrane for solid-phase microextraction. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2003; 17:936-942. [PMID: 12717766 DOI: 10.1002/rcm.993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The use of custom-made solid-phase microextraction (SPME) fibers coated with a perfluorosulfonated ionomer, Nafion, was investigated for nitrogen isotopic analysis of ammonium in aqueous solutions. Aqueous ammonium was converted to ammonia by addition of a base, followed by absorption from the headspace, desorption in the injection port of a gas chromatograph, and analysis by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Fibers coated with a Nafion tubing were chosen due to a higher fiber-gas distribution constant and a higher Nafion thickness than fibers coated with Nafion solution, both leading to a higher amount of ammonia absorbed at equilibrium. The Nafion membrane-coated fiber absorbed approximately 20 times more than a commercial polydimethylsiloxane (PDMS) fiber. The isotopic fractionation between fiber and gas was 1.0117 +/- 0.0009 (standard deviation, SD, of all measurements) at an initial ammonia gas concentration of 21-210 microM. At 390 microM initial gas concentration it was slightly lower. When sampling from liquid samples, an ammonium concentration of 10 mM was needed to obtain a sufficient amount of ammonia absorbed. Modeling of the absorption at different temperatures showed that the absorption was approximately constant in the temperature range suitable for SPME experiments. Absorption at room temperature was therefore used for simplicity. A pilot study was conducted in which absorption was achieved from a single 9 microL droplet of sample. The preliminary results showed that delta(15)N analysis was possible for only 0.4-0.5 micromol of ammonium with a SD of 0.8 per thousand (n = 5).
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Affiliation(s)
- Elin Norlin
- Swedish University of Agricultural Sciences, Department of Forest Ecology, Section of Soil Science, SE-901 83 Umeå, Sweden.
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Rhofir C, Hawari J. Application of solid-phase microextraction-gas chromatography-mass spectrometry to characterize intermediates in a joint solar-microbial process for total mineralization of Aroclor 1254. J Chromatogr A 2000; 873:53-61. [PMID: 10757284 DOI: 10.1016/s0021-9673(99)00922-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
A combined solid-phase microextraction-GC-MS analytical technique was used to monitor the formation of metabolites in the biodegradation of biphenyl, which were originally obtained from the solar photodechlorination of Aroclor 1254 by Pseudomonas pseudoalcaligenes KF707 and Burkholderia sp LB400. In both cases, the following metabolites were detected: 2-hydroxybiphenyl (2-OH-BP), 2,3-dihydroxybiphenyl (2,3-di-OH-BP), and benzoic acid, which was detected as its benzoate derivative 1-methylethylbenzoate. A time course study for the formation and disappearance of these metabolites was used to construct a degradation pathway, which in both cases, involved the formation of 2-OH-BP and 2,3-di-OH-BP.
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Affiliation(s)
- C Rhofir
- Biotechnology Research Institute, National Research Council Canada, Montreal
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Lichtfouse E. Compound-specific isotope analysis. Application to archaeology, biomedical sciences, biosynthesis, environment, extraterrestrial chemistry, food science, forensic science, humic substances, microbiology, organic geochemistry, soil science and sport. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2000; 14:1337-1344. [PMID: 10920352 DOI: 10.1002/1097-0231(20000815)14:15<1337::aid-rcm9>3.0.co;2-b] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The isotopic composition, for example, (14)C/(12)C, (13)C/(12)C, (2)H/(1)H, (15)N/(14)N and (18)O/(16)O, of the elements of matter is heterogeneous. It is ruled by physical, chemical and biological mechanisms. Isotopes can be employed to follow the fate of mineral and organic compounds during biogeochemical transformations. The determination of the isotopic composition of organic substances occurring at trace level in very complex mixtures such as sediments, soils and blood, has been made possible during the last 20 years due to the rapid development of molecular level isotopic techniques. After a brief glance at pioneering studies revealing isotopic breakthroughs at the molecular and intramolecular levels, this paper reviews selected applications of compound-specific isotope analysis in various scientific fields.
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Affiliation(s)
- E Lichtfouse
- Soil and Environment Laboratories, INRA-ENSAIA/INPL, BP 172, 54505 Vandoeuvre-les-Nancy, France.
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van Doorn H, Grabanski CB, Miller DJ, Hawthorne SB. Solid-phase microextraction with pH adjustment for the determination of aromatic acids and bases in water. J Chromatogr A 1998; 829:223-33. [PMID: 9923082 DOI: 10.1016/s0021-9673(98)00760-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Adjusting the pH of water samples before performing solid-phase microextraction (SPME) analysis can be used to selectively extract organic acids (at pH 2) and bases (at pH 12). Sorption behavior of test organics is predictable based on the acid dissociation constant in water. In general, polyacrylate (PA) and Carbowax-divinylbenzene (CW-DVB) show substantially higher fiber/water sorption coefficients (Kd values) than a polydimethylsiloxane (PDMS) coated fiber. Gas chromatography-flame ionization detection (GC-FID) detection limits with the CW-DVB sorbent are approximately 0.5 to 10 ng/ml in a 2-ml water sample for a variety of aromatic amines, phenols, and chlorinated phenols, and are approximately 1 to 50 ng/ml for the same solutes using the PA sorbent. However, the PA fiber is more selective (depending on the water pH) for the acid or base components than the CW-DVB fiber. With proper pH adjustment, the recovery of spiked aromatic amines and phenols from a surface wetlands water ranged from 73 to 118% of the known values, with a precision (R.S.D.) of approximately 5 to 20%. SPME quantitation of phenols in a coal gasification wastewater using a PA fiber also gave excellent agreement with conventional methylene chloride extraction, although continued use of a single fiber with this wastewater led to poorer precision.
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Affiliation(s)
- H van Doorn
- Energy & Environmental Research Center, University of North Dakota, Grand Forks 58202-9018, USA
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Koster EHM, Hofman NSK, de Jong GJ. Direct solid-phase microextraction combined with gas and liquid chromatography for the determination of lidocaine in human urine. Chromatographia 1998. [DOI: 10.1007/bf02467453] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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