EXTRACTION AND DETERMINATION OF BUTYLTIN COMPOUNDS IN SHELLFISH BY HYDRIDE GENERATION GAS-CHROMATOGRAPHY QUARTZ FURNACE ATOMIC-ABSORPTION SPECTROMETRY

The method described involves the conversion of butyltin compounds extracted from shellfish into volatile hydrides by sodium tetrahydroborate, cryogenic trapping and selective volatilization followed by on-line quartz furnace atomic absorption spectrometric detection. Several sample pretreatment procedures were compared with emphasis on their accuracy, reproducibility and respect for the speciation of tin. Digestion with 0.083 M HCl in 16.7% methanol under sonication for 1 h- is proposed. The recoveries of mono-, di- and tributyltin compounds from spiked mussel and oyster samples ranged from 96 to 99% with low degradation of butyltins (< 9%). Detection limits were in the 2-3 ng Sn g(-1) (wet weight) range. The method was applied to wild and commercial samples of oysters, mussels and scallops and fairly high concentrations of butyltin compounds were measured.