A simple method for the speciation of organotin compounds in water samplesusing ethylation and GC-QFAAS

A simple method for the extraction of organotin compounds from water sample s was developed in which both the instrumental parameters and the extractio n/derivatization step were optimized. Organotin compounds (butyl-, phenyl- and octyl-) in tap water samples were ethylated with the addition of 2.5 ml of 0.4% w/v NaBEt4 at pH 5.00 and subsequently extracted two times, for 10 min, with 3 and 2ml of hexane. The combined extracts were analyzed with on- column capillary GC-QFAAS. The recoveries were quantitative for di- and tri - alkyltin compounds, whereas between 67 and 86% of the monoalkyltin compou nds were recovered. The detection limits obtained ranged from 110pg for mon obutyltin to 500 pg for triphenyltin, as sensitivities were found to be com pound dependent. The preparation of ethylated standards was also optimized. It was found that two subsequent extractions, with 1.0 and 0.5 mi of hexan e were necessary for the quantitative recovery of the ethylated organotin c ompounds.