SUPERCRITICAL-FLUID EXTRACTION OF TRIBUTYLTIN AND ITS DEGRADATION PRODUCTS FROM SEAWATER VIA LIQUID-SOLID PHASE EXTRACTION

Quantitative extraction of di- and tributyltin compounds from aqueous matrices using C-18 liquid-solid extraction (LSE) discs, followed by i n situ Grignard ethylation and supercritical fluid extraction of deriv atized LSE discs, is demonstrated for the first time. The optimum extr action efficiency of dibutyltin and tributyltin from synthetic seawate r at pH 2 was achieved by using a combination of static and dynamic ex traction procedures with supercritical carbon dioxide (10 MPa, 40 degr ees C). The extraction efficiency for dibutyltin and tributyltin range d from 92 to 102%, and the R.S.D.s (n = 5) were 6.6 and 8.2%, respecti vely. The limit of detection of tributyltin (1 l of seawater) using a capillary gas chromatograph coupled to a single-flame tin-selective fl ame photometric detector was 6 ng/l, while the limit of quantitation o f harbour seawater was 9 ng/l. Furthermore, analysis time and solvent usage are reduced by 50 and 90%, respectively, in comparison with clas sical methods involving liquid-liquid extraction in the presence of co mplexing agents.