GC FPD METHOD FOR THE SIMULTANEOUS SPECIATION OF BUTYLTIN AND PHENYLTIN COMPOUNDS IN WATERS

A method is described for the simultaneous determination of nanogram amounts of mono-, di- and tri-butyltin compounds and mono-, di- and triphenyltin compounds in water. The procedure is based on the conversion of tin compounds to volatile species by Grignard pentylation and analysis using GC with flame photometric detection (GC FPD). The ionic compounds are extracted from diluted acidified (HBr) aqueous solutions by using a pentane-tropolone solution. The extracted organotin compounds are pentylated by a Grignard reagent and purified on a Fluorisil column before analysis by GC FPD. The detection limits are 20 ng dm-3 for butyltin compounds and 50 ng dm-3 for phenyltin compounds. Recoveries from spiking experiments in tap-water and natural seawater matrices, in which no organotin compounds were detected, were greater than 90% for most of the alkyltin compounds.