Identification of organic arsenic, tin, antimony and tellurium compounds in environmental samples by GC-MS

Abstract

Abstract In this study, the potential of GC-MS for structure analysis of organometal(loid) species of arsenic, tin, antimony and tellurium in environmental samples was investigated. Analytes were ionic organometal(loid) species from compost samples, which were derivatised with NaBH 4 before introduction into the GC/MS via a purge and trap system, as well as volatile species from hydrothermal gases sampled on SPME-fibres. Several organic species of arsenic, tin, antimony and tellurium were identified. By scanning the chromatogram for typical fragments of organoarsenic compounds seven arsenic species were identified. To our knowledge three of them (diarsine, monomethyl diarsine and dimethylarsenomercaptane) have not been reported in environmental samples so far. To further exclude artefacts being misinterpreted as volatile organometal(loid)s, measurements of volatile arsenic species naturally occurring in hydrothermal samples with SPME-GC-MS were performed. The determination of dimethylarsenomercaptane in these samples confirms that this compound which was also found after derivatisation of ionic arsenic species is not an artefact. A strategy for the identification of unknown species whose structure cannot be elucidated by library comparison or with the help of isotopic patterns is presented. The necessity of positive identification of unknown species and confirmation of known and assumed compounds for speciation analysis is highlighted and the applicability of quadrupol GC/MS for this purpose is stated.