Trace metal speciation via supercritical fluid extraction–liquid chromatography–inductively coupled plasma mass spectrometry

Supercritical fluid CO2 was used for the extraction of organotin compounds present in fish. A sample of tuna fish was spiked with trimethyltin chloride, tributylin chloride and triphenyltin chloride. Parameters such as cartridge size, type of modifier, and type and temperature of the restrictor were evaluated for the spiked sample. Extraction conditions were optimized by measuring total metal content using ICP-MS detection. The extracts were also analysed by LC–ICP-MS. Optimized extraction conditions were applied to a fish tissue CRM that contained tributyltin and triphenyltin. LC–ICP-MS analysis indicated that the extracted species varied with the modifier used. Extraction efficiencies for the CRM were lower when compared with the results obtained for the spiked samples using the same extraction conditions. However, extraction efficiencies were up to 80% for trimethyltin and 40% for triphenyltin with the fish tissue CRM when 1% water was added as a modifier and diethyldithiocarbamic acid ammonium salt or pyrrolidinecarbothioic acid ammonium salt were added as complexing agents.