ACID LEACHING SOLVENT-EXTRACTION TREATMENT OF SEDIMENT SAMPLES FOR ORGANOTIN SPECIATION

A method is described for leaching of nanogram amounts of monobutylin (MBT), dibutyltin (DBT) and tributyltin (TBT) and monophenyltin (MPT), diphenyltin (DPT) and triphenyltin (TPT) from sediments. The procedur e is based on soaking the sediments in water-hydrogen bromide mixture (1:1) with magnetic stirring for 30 min followed by extraction with 0. 04% (w/v) tropolone solution in dichloromethane for 2 h. Organotins ar e determined by gas chromatography with a flame photometric detector ( GC-FPD) after cleanup through a Florisil column and derivatization by Grignard pentylation. The method has been applied to the study of wate r and sediments in different areas of the south-west Spain. Predominan t species are butyltins, especially TBT which rise critical levels in waters and sediments of fishering harbours. In this study it has been found a direct relation between organotin levels and distance to poten tial sources determined by boating activities. In addition, it has bee n verified the relative occurrence of DBT and MBT together with TBT, p ossibly as a result of a degradation process, and the influence of sed iment grain size and organic matter content on organotins accumulation .