title: Compound-specific chlorine isotope analysis: a comparison of gas chromatography/isotope ratio mass spectrometry and gas chromatography/quadrupole mass spectrometry methods in an interlaboratory study.
abstract: Chlorine isotope analysis of chlorinated hydrocarbons like trichloroethylene (TCE) is of emerging demand because these species are important environmental pollutants. Continuous flow analysis of noncombusted TCE molecules, either by gas chromatography/isotope ratio mass spectrometry (GC/IRMS) or by GC/quadrupole mass spectrometry (GC/qMS), was recently brought forward as innovative analytical solution. Despite early implementations, a benchmark for routine applications has been missing. This study systematically compared the performance of GC/qMS versus GC/IRMS in six laboratories involving eight different instruments (GC/IRMS, Isoprime and Thermo MAT-253; GC/qMS, Agilent 5973N, two Agilent 5975C, two Thermo DSQII, and one Thermo DSQI). Calibrations of (37)Cl/(35)Cl instrument data against the international SMOC scale (Standard Mean Ocean Chloride) deviated between instruments and over time. Therefore, at least two calibration standards are required to obtain true differences between samples. Amount dependency of δ(37)Cl was pronounced for some instruments, but could be eliminated by corrections, or by adjusting amplitudes of standards and samples. Precision decreased in the order GC/IRMS (1σ ≈ 0.1‰), to GC/qMS (1σ ≈ 0.2-0.5‰ for Agilent GC/qMS and 1σ ≈ 0.2-0.9‰ for Thermo GC/qMS). Nonetheless, δ(37)Cl values between laboratories showed good agreement when the same external standards were used. These results lend confidence to the methods and may serve as a benchmark for future applications.
authors.affiliation: Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, 85764 Neuherberg, Germany.
authors.forename: Anat
authors.initials: A
authors.lastname: Bernstein
authors.forename: Orfan
authors.initials: O
authors.lastname: Shouakar-Stash
authors.forename: Karin
authors.initials: K
authors.lastname: Ebert
authors.forename: Christine
authors.initials: C
authors.lastname: Laskov
authors.forename: Daniel
authors.initials: D
authors.lastname: Hunkeler
authors.forename: Simon
authors.initials: S
authors.lastname: Jeannottat
authors.forename: Kaori
authors.initials: K
authors.lastname: Sakaguchi-Söder
authors.forename: Jens
authors.initials: J
authors.lastname: Laaks
authors.forename: Maik A
authors.initials: MA
authors.lastname: Jochmann
authors.forename: Stefan
authors.initials: S
authors.lastname: Cretnik
authors.forename: Johannes
authors.initials: J
authors.lastname: Jager
authors.forename: Stefan B
authors.initials: SB
authors.lastname: Haderlein
authors.forename: Torsten C
authors.initials: TC
authors.lastname: Schmidt
authors.forename: Ramon
authors.initials: R
authors.lastname: Aravena
authors.forename: Martin
authors.initials: M
authors.lastname: Elsner
mesh_terms: D002138:Calibration; D002713:Chlorine / Q000032:analysis* / Q000592:standards; D004785:Environmental Pollutants / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000295:instrumentation / Q000592:standards; D007553:Isotope Labeling; D007554:Isotopes / Q000032:analysis* / Q000592:standards; D014241:Trichloroethylene / Q000032:analysis
chemical_list: D004785:Environmental Pollutants; D007554:Isotopes; D014241:Trichloroethylene; D002713:Chlorine