DETERMINATION OF BUTYLTIN COMPOUNDS IN SEDIMENT USING GAS-CHROMATOGRAPHY ATOMIC-ABSORPTION SPECTROMETRY - COMPARISON OF SODIUM TETRAHYDROBORATE AND SODIUM TETRAETHYLBORATE DERIVATIZATION METHODS

Aqueous ethylation and hydride generation, two rapid, convenient speciation techniques used for the determination of butyltin species in river sediments, were compared. After extracting the sediment with methanol containing 0.5 M HCl, the extract was derivatized and analysed by gas chromatography-atomic absorption spectrometry. Monobutyltin and dibutyltin can be determined quantitatively using the hydride generation method; for tributyltin, the analysis suffers from critical interference from the sediment extract. With the ethylation method, quantitative determination of dibutyltin and tributyltin in the sediment can be achieved, while a lower recovery of monobutyltin is observed. The detection limits for butyltins in sediments are significantly improved by this method because no foaming occurs during the ethylation step and because the analytical procedure is not hampered by interference from sediment extracts. The detection limits are 0.20, 0.10 and 0.44 ng Sn g-1 dry sediment for mono-, di- and tributyltin, respectively.