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Anal Chem

Title:		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
Author(s):		Herrero-Martin S; Nijenhuis I; Richnow HH; Gehre M;
Address:		"Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research , Permoserstrasse 15, D-04318 Leipzig, Germany"
Journal Title:		Anal Chem
Year:		2015
Volume:		20150107
Issue:		2
Page Number:		951 - 959
DOI:		10.1021/ac503229e
ISSN/ISBN:		1520-6882 (Electronic) 0003-2700 (Linking)
Abstract:		"One major challenge for the environmental application of compound-specific stable isotope analysis (CSIA) is the necessity of efficient sample treatment methods, allowing isolation of a sufficient mass of organic contaminants needed for accurate measurement of the isotope ratios. Here, we present a novel preconcentration technique--the coupling of a headspace (HS) autosampler with a programmed temperature vaporizer (PTV)--for carbon (delta(13)C) and hydrogen (delta(2)H) isotope analysis of volatile organic compounds in water at concentrations of tens of micrograms per liter. The technique permits large-volume injection of headspace samples, maintaining the principle of simple static HS extraction. We developed the method for multielement isotope analysis (delta(13)C and delta(2)H) of methyl tert-butyl ether (MTBE), benzene, toluene, ethylbenzene, and o-xylene (BTEX), and analysis of delta(13)C for chlorinated benzenes and ethenes. Extraction and injection conditions were optimized for maximum sensitivity and minimum isotope effects. Injection of up to 5 mL of headspace sample from a 20 mL vial containing 13 mL of aqueous solution and 5 g of NaCl (10 min of incubation at 90 degrees C) resulted in accurate delta(13)C and delta(2)H values. The method detection limits (MDLs) for delta(13)C were from 2 to 60 mug/L (MTBE, BTEX, chlorinated ethenes, and benzenes) and 60-97 mug/L for delta(2)H (MTBE and BTEX). Overall, the HS-PTV technique is faster, simpler, isotope effect-free, and requires fewer treatment steps and less sample volume than other extraction techniques used for CSIA. The environmental applicability was proved by the analysis of groundwater samples containing BTEX and chlorinated contaminants at microgram per liter concentrations"
Keywords:
Notes:		"PubMed-not-MEDLINEHerrero-Martin, Sara Nijenhuis, Ivonne Richnow, Hans H Gehre, Matthias eng 2014/12/17 Anal Chem. 2015 Jan 20; 87(2):951-9. doi: 10.1021/ac503229e. Epub 2015 Jan 7"