Comparison of sulphur-mode and tin-mode flame photometric detectors for the gas chromatographic determination of organotin compounds.

A comparison of sulphur-mode (393 nm) and tin-mode (610 nm) flame photometric detectors for the gas chromatographic determination of butyl- and phenyltin compounds is described. The chromatographic peaks of the butyl- and phenyltin compounds were well separated, and high sensitivity was achieved in both modes; however, the tin-mode was more specific for tin compounds than the sulphur-mode. The absolute detection limits with the sulphur-mode and the tin-mode were 3.9-7.6 pg and 2.6-5.1 pg as tin, respectively. The application of the tin-mode gas chromatographic method to the determination of organotin compounds in fish is presented. For this application, organotins are extracted (as chloride) with hydrochloric acid and n-hexane-benzene (3:2, containing 0.05% tropolone) and the extracts are pentylated by a Grignard reagent prior to gas chromatography. The absolute recoveries of butyl- and phenyltin compounds added to fish samples ranged from 68.5 to 84.4% (the coefficients of variation were less than 6.6% for all substances, n = 8). Significant amounts of three organotin compounds (di- and tributyltin and triphenyltin) in fish samples were detected by this method. This technique may have application for other organotin compounds and the monitoring of butyl- and phenyltin compounds in the environment.