Determination of tri-n-butyltin and di-n-butyltin compounds in fish by gas chromatography with flame photometric detection

An analytical method is described for the simultaneous quantitative determination of tri-n-butyltin and di-n-butyltin compounds in fish. The sample was extracted with 0.5N HCl-methanol, and the methanol solution was extracted with hexane. The extract was purified by gel permeation chromatography and treated with Grignard reagent to yield the methyl derivatives, which were determined by gas chromatography with flame photometric detection operated in the tin mode (610 nm). Recoveries of tri-n-butyltin chloride (Bu3SnCl) and di-n-butyltin dichloride (Bu2SnCl2) spiked to fish at the levels of 0.2 and 1.0 ppm ranged from 80 to 105%. Detection limits were 0.02 micrograms/g for both compounds. Tri-n-butyltin compounds equivalent to Bu3SnCl levels of 0.07-2.0 ppm and di-n-butyltin compounds equivalent to Bu2SnCl2 levels of 0.02-0.11 ppm were found in reared yellowtails, and these values showed good agreement with the results from gas chromatographic-mass spectrometric analysis.