Application of “Clean-up” Cartridge for Gas Chromatographic Determination of Di- and Tri-n-butyltin in Fish

Abstract

A gas chromatographic method is presented to determine traces of di- and tri-n-butyltin compounds in fish by use of an innovative clean-up cartridge. The cartridge used was packed with a moderately sulfonated low capacity cation exchange resin. The organotin compounds in fish tissue were extracted with hydrochloric acid-ethanol solution as their chlorides, transferred to an ethylacetate/hexane phase by liquid-liquid extraction, and the organic layer was concentrated with a rotary evaporator. The organotin chlorides were trapped on the resin by passing through the cartridge. The sampled cartridge was washed successively with ethanol, water and sodium chloride solution. The trapped organotin compounds were converted to their hydrides by passing a sodium borohydride ethanol solution through the cartridge, and these hydrides were eluted with 1/1 hexane/ethanol. The eluted organotin hydrides were extracted with hexane by shaking the eluate with water and hexane. The hexane layer was subjected to gas chromatographic separation, and identified by mass spectroscopy. The di- and tri-n-butyltin compounds in a fish sample could be determined as their chlorides with 2.7–4.8% relative standard deviations in the range 0.1–2.0 ng/g. The detection limits of di- and tri-n-butyltin compounds as their chlorides were 3 ng/g and 8 ng/g for 10 g of the sample.