SPECIATION ANALYSIS OF ORGANOTIN IN THE RIVER SCHELDT BY CAPILLARY GAS-CHROMATOGRAPHY ATOMIC-EMISSION SPECTROMETRY (GC-AES)

Two rapid, sensitive and interference-free analytical procedures were developed for the comprehensive speciation analysis of ionic butyl- and phenyltin compounds in water. One of them based on ethylation of ionic organotin in the aqueous phase with sodium tetraethylborate (NaBEt4) followed by the extraction of the derivatized species into hexane. The other method involved preconcentration of ionic organotin on a C18 cartridge followed by on-column ethylation in a semi-automated flow system. Separation and determination of organotin species were performed by capillary gas chromatography with microwave induced plasma atomic emission detection (GC-MIP AED). 20-50 ml of sample was sufficient for the analysis and a detection limit of 0.1 ng/l (as Sn) was obtained. The methods were applied to the determination of organotin in the river Scheldt at 15 locations close to the Antwerp agglomeration. Butyltin compounds were detected in all the analyzed samples at concentrations ranging between 10-140 ng/l, 8-70 ng/l and 4-10 ng/l for the mono-, di- and tributyltin in the dissolved phase, respectively. No phenyltin species were detected. The agreement between die results obtained by different methods was within 15%.