DETERMINATION OF ORGANOTINS IN NATURAL WATERS BY TOLUENE EXTRACTION GRAPHITE FURNACE AAS
Report No DWI0661

Jul l987

SUMMARY

The determination of tributyltin in natural waters by toluene extraction and graphite furnace AAS detection of tin has been investigated. The effect of pH on the extraction of mono-, di-, tributyltin and triphenyltin, has been examined and the optimum c onditions for the estimation of tributyltin assessed. Investigation of graphite furnace conditions has shown that AAS performance is greatly improved by using furnace tubes pretreated by soaking in sodium tungstate solution. Such pretreatment is essential if low detection limits are to be attained. On extraction from aqueous media, a marked signal enhancement effect was observed (irrespective of furnace tube type) which varied according to the nature of the aqueous solution. The enhancement effect is believed to result from water in the toluene extract activating the tube surface. Methods for the estimation of tributyltin in waters that are appropriate for screening samples as part of routine monitoring programmes, are described. Using a 1 litre sample, limits of detection (based on 4.65 times the within-batch standard deviation of the blank) of below 4 ng Sn/l were attained. Relative standard deviation on six replicate analyses of seawater containing 170 ng Sn/l of tributyltin was 1.3%.

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