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Compound-Specific Chlorine Isotope Analysis of Tetrachloromethane and Trichloromethane by Gas Chromatography-Isotope Ratio Mass Spectrometry vs Gas Chromatography-Quadrupole Mass Spectrometry: Method Development and Evaluation of Precision and Trueness

Benjamin Heckel, Diana Rodriguez-Fernandez, Clara Torrento Aguerri, Armin Meyer, Jordi Palau Capdevila, Christina Domenèch, Mònica Rosell, Albert Soler, Daniel Hunkeler & Martin Elsener

Résumé Compound-specific chlorine isotope analysis of tetrachloromethane (CCl4) and trichloromethane (CHCl3) was explored by both, gas chromatography-isotope ratio mass spectrometry (GC-IRMS) and GC-quadrupole MS (GC-qMS), where GC-qMS was validated in an interlaboratory comparison between Munich and Neuchâtel with the same type of commercial GC-qMS instrument. GC-IRMS measurements analyzed CCl isotopologue ions, whereas GC-qMS analyzed the isotopologue ions CCl3, CCl2, CCl (of CCl4) and CHCl3, CHCl2, CHCl (of CHCl3), respectively. Lowest amount dependence (good linearity) was obtained (i) in H-containing fragment ions where interference of 35Cl- to 37Cl-containing ions was avoided; (ii) with tuning parameters favoring one predominant rather than multiple fragment ions in the mass spectra. Optimized GC-qMS parameters (dwell time 70 ms, 2 most abundant ions) resulted in standard deviations of 0.2‰ (CHCl3) and 0.4‰ (CCl4), which are only about twice as large as 0.1‰ and 0.2‰ for GC-IRMS. To compare also the trueness of both methods and laboratories, samples from CCl4 and CHCl3 degradation experiments were analyzed and calibrated against isotopically different reference standards for both CCl4 and CHCl3 (two of each). Excellent agreement confirms that true results can be obtained by both methods provided that a consistent set of isotopically characterized reference materials is used.
   
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Citation Heckel, B., Rodriguez-Fernandez, D., Torrento Aguerri, C., Meyer, A., Palau Capdevila, J., Domenèch, C., Rosell, M., Soler, A., Hunkeler, D., & Elsener, M. (2017). Compound-Specific Chlorine Isotope Analysis of Tetrachloromethane and Trichloromethane by Gas Chromatography-Isotope Ratio Mass Spectrometry vs Gas Chromatography-Quadrupole Mass Spectrometry: Method Development and Evaluation of Precision and Trueness. Analytical Chemistry, 89, 3411-3420.
   
Type Article de périodique (Anglais)
Date de publication 3-2017
Nom du périodique Analytical Chemistry
Volume 89
Pages 3411-3420
URL https://DOI.org/10.1021/acs.analchem.6b04129