The determination of organotins in fish and shellfish

Just as MeHg has become a widely distributed and commonly found environmental pollutant in many fish species, especially swordfish and tunafish, so too has tribulyl tin (TBT) gained in recognition as an even more widely distributed aquatic pollutant and toxicant [53], TBT can now be found in almost all fish/shellfish samples taken anywhere in the world, even from native salmon in Scotland, Denmark, Norway, or elsewhere. The U.S. Food and Drug Administration (FDA) has, in part, a responsibilily to continuously monitor foods imported into the U.S. destined for human consumption. It was, in part, the purpose of this study to develop improved GC-element selective detection (ESD) approaches for organotins in fish and shellfish. And, to then utilize such newer, validated approaches for as many real world marine samples as possible and practical. 

By and large, most currently employed approaches for the accurate and precise quantitation of TBT and other butyltins rely on GC with some type of element selective or specific detection technique. Most of these use flame photometric detection (FPD) with a tin specific filter at GOOnm emission. Though somewhat selective for tin containing species, it is not 100% specific for tin alone. Thus, the combination of GC with FPD and DCP appeared to be a very reliable and practical approach to obtain one and/or two selective chromatograms from one or two injections of a fish or shellfish extract. 

Most literature reports have utilized some type of pre-injection deriva-tization for TBT and the other butyltin species. Such approaches have generally used hydridization or alkylation, in order to provide improved GC performance characteristics for the original species. Improvements in the off-column derivatization methods generally reported have quite recently used reaction GC to form the hydrides of TBT and its analogs prior to FPD detection [62-64]. This remains an entirely feasible, continuous, and automatable approach to perform on-column reactions in GC, especially for compounds such as TBT which can readily form metal/element hydrides. 

There have been very few reports on the direct GC determination of butyltins without some type of pre-column derivatization [65]. In general, those reports that used direct injection, have shown broadened peak shapes, serious tailing of peaks, poor column eflficiencies, and less-than-ideal peak resolution or capacity. An ideal GC-element selective detection (ESD) method might involve the following steps (1) simple sample work-up and extraction from fish/shellfish with high recovery 

All four organotins of current environmental or FDA interest have been baseline resolved, without prior derivatization, using the GC-FPD conditions indicated in Fig. 9.6 [53]. Similar chromatograms, not 

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