Analytical and Bioanalytical Chemistry

, Volume 384, Issue 1, pp 237–243

Establishing a chromium-reactor design for measuring δ2H values of solid polyhalogenated compounds using direct elemental analysis and stable isotope ratio mass spectrometry

  • Wolfgang Armbruster
  • Katja Lehnert
  • Walter Vetter
Original Paper

DOI: 10.1007/s00216-005-0160-0

Cite this article as:
Armbruster, W., Lehnert, K. & Vetter, W. Anal Bioanal Chem (2006) 384: 237. doi:10.1007/s00216-005-0160-0

Abstract

2H/1H isotope ratios of polyhalogenated compounds were determined by elemental analysis and isotope ratio mass spectrometry (EA-IRMS). Initial measurements with standard EA-IRMS equipment, which used high-temperature pyrolysis to convert the organic compounds into hydrogen, did not achieve significant signals for polychlorinated pesticides and related compounds, presumably due to the formation of HCl instead of hydrogen. To reverse this problematic reaction, a chromium reactor was incorporated into the element analyzer system, which scavenged Cl, forming chromium chloride and releasing hydrogen again in the form of H2. The optimized system therefore allowed the δ2H values of polyhalogenated compounds to be determined. A quality assurance program was developed based on several parameters. (i) Each compound was analyzed using a sequence of five injections, where the first measurement was discarded. (ii) Recovery of H (when calculated relative to acetanilide) had to be >90% for all replicates in a sequence. (iii) All δ-values within a sequence had to vary by less than 10‰. (iv) Results had to be reproducible on another day with a different sample scheme. Once this reproducibility had been established, variabilities in the δ2H values of organohalogen standards were investigated using the technique. The highest δ2H value of +75‰ was found for o,p´-DDD, whereas the strongest depletion in deuterium was found for Melipax (–181‰). The most important results for comparable compounds were as follows. DDT-related compounds gave δ2H values of between +59 and +75‰ (technical DDT, o,p´- and p,p´-DDD) or in the range of approximately −1‰, indicative of the different sources/methods of producing this compound. Four HCH isomers from the same supplier showed relatively similar hydrogen isotope distributions, whereas two lindane (γ–HCH) standards from other sources had 39‰ less deuterium. This difference is likely due to different purification steps during the isolation of pure lindane from the technical HCH mixture. An even greater difference was observed between the δ2H values of Toxaphene (US product dating from 1978) and Melipax (product from the former East Germany, dating from 1979), which gave δ2H values of –101‰ and –181‰, respectively, meaning that both products were easily distinguished via δ2H-IRMS. Fractioning of hydrogen isotopes in the atmospheric water cycle was suggested as one reason for the different values. In this theory, the water (which had different δ2H values depending on where it was taken from) was incorporated during the biosynthesis of camphene, which is the natural product used to produce both products. These results indicate that hydrogen isotope-specific analysis can be a valuable tool for tracing the origins of a compound in certain cases.

Keywords

Stable hydrogen isotope ratios EA-IRMS δ2Chromium reactor Polyhalogenated compounds 

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Wolfgang Armbruster
    • 1
  • Katja Lehnert
    • 2
  • Walter Vetter
    • 2
  1. 1. Institute of Food Chemistry, Department of Food Chemistry and Analytical ChemistryUniversity of HohenheimStuttgartGermany
  2. 2. Institute of Food Chemistry, Department of Food ChemistryUniversity of HohenheimStuttgartGermany

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