Speciation of Underivatized Organotin Compounds in Sediments by Gas Chromatography-triple Quadrupole Mass Spectrometry

Tributyltin is well recognized as an environmental endocrine disruptor and is listed as a priority substance that requires extended monitoring by the European Water Framework Directive (2000/60/EC). At the same time, due to their high pathogenicity, producing hormonal, immune, metabolic and reproductive dysfunctions, other butyltin species (e.g. monobutyltin, dibutyltin and tetrabutyltin) are consistently monitored in marine and freshwater aquatic ecosystems; the European Chemicals Agency classified these butyltin species as potential carcinogens and toxic substances for the human reproduction. Several analytical techniques, including gas chromatography and high-performance liquid chromatography, have been used to determine organotin species in aquatic ecosystems. Because of their chemical properties, organotin compounds result poorly stable upon temperature and are thus unsuited for direct analysis through capillary gas chromatography, which is usually performed after a derivatization step. The procedure described in this paper allowed the detection of underivatized chlorinated organotin compounds through gas chromatography-triple quadrupole mass spectrometry. Importantly, the obtained spectra of chlorinated monobutyltin and dibutyltin are herein presented and the fragmentation patterns are identified for the first time. The method was successfully applied to evaluate organotin compounds in sediments, providing the speciation of organotin species. Taking advantage of a simplified procedure of sample treatment, this study provided an innovative protocol for the gas chromatography/mass spectrometry of phenyl and butyl-substituted organotin compounds in contaminated sediments, capable of improving the efficiency of the conventional analysis of organotin compounds.