ACID-EXTRACTION TREATMENT OF SEDIMENT SAMPLES FOR ORGANOTIN SPECIATION - OCCURRENCE OF BUTYLTIN AND PHENYLTIN COMPOUNDS ON THE CADIZ COAST,SOUTH-WEST SPAIN

A method is described for leaching of nanogram amounts of mono-, di an d tri-butyltin compounds and mono-, di- and tri-phenyltin compounds fr om sediments, The procedure is based on soaking the sediments in a wat er-hydrogen bromide mixture (2:3) with magnetic stirring for Ih follow ed by extraction with 0.02% (w/v) tropolone solution in pentane for 2 h. Organotins are determined by GF FPD after clean-up through a Floris il column and derivatization by Grignard pentylation, The method has b een applied to the study of water and sediments in different areas of south-west Spain, Predominant species are butyltins, especially tribut yltin (TBT), which has high values in waters and sediments of Puerto d e Santa Maria and Cadiz Bay, as well as in sediments of the Sancti Pet ri Channel, which suggests a harmful action on biota, A direct relatio n has been found beween organotin levels and distance of potential foc us determined by boating activities, In addition, the relative occurre nce of dibutyltin (DBT) and monobutyltin (MET) together with TBT has b een noted, possibly as a result of a degradation process, and the infl uence of grain size of sediment and presence of organic matter on orga notin accumulation has been studied.