SPECIATION ANALYSIS FOR ORGANOTIN COMPOUNDS IN SEDIMENTS BY CAPILLARYGAS-CHROMATOGRAPHY WITH FLAME PHOTOMETRIC DETECTION AFTER MICROWAVE-ASSISTED ACID LEACHING

A rapid method is described for the speciation of butyl- and phenyltin compounds in sediments. The procedure was based on the quantitative m icrowave-assisted leaching of the target compounds from a sediment sam ple with ethanoic acid followed by their derivatization with sodium te traethylborate-in the aqueous phase, The ethyl derivatives of the anal yte compounds were subsequently extracted into iso-octane and separate d by capillary GC, A modified flame photometer with a graphite burner fitted with a 610 nm bandpass filter was used for detection, A desulfu rization procedure used prior to GC was optimized and then incorporate d into the analytical scheme in order to remove the sulfur present in sediments which would otherwise interfere with the detection of the or ganotin compounds, The leaching of the analyte species in a focused mi crowave field took only 3-4 min and the analysis time was limited by t he duration of the gas chromatographic run (15 min), The effects of pH , temperature and time for ethylation of methyl-, butyl-, phenyl-, oct yl- and dodecyltin compounds were evaluated, The possibility Of accele rating the ethylation, by using a focused microwave field, was examine d, The detection limit of the procedure was 10 ng g(-1) for 0.5 g of s ediment, Atypical precision for this determination was 5-10%, The meth od developed was validated by analysing two CRMs (NRCC PACS-1 and BCR CRM 462), A series of applications in the Arcachon Bay and Greek coast al monitoring programme demonstrated the presence of butyl and phenylt in species.