Rapid Ultratrace Analysis of Tributyltin in Aqueous Matrixes by Purge-and-Trap Gas Chromatography with Flame Photometric Detection

A simplified purge-and-trap technique for detecting subnanogram amounts of the biocide tributyltin (TBT) and its degradation products dibutyltin (DBT) and monobutyltin (MBT) in aqueous environmental samples is described. Butyltin chlorides present in the sample were derivatized to volatile butyltin hydrides with NaBH4 and simultaneously purged by drawing ambient air through the purge vessel. Butyltin hydrides were trapped on a Porapak-N cartridge, eluted with dichloromethane, and analyzed by gas chromatography with flame photometric detection. Recoveries of the butyltin species ranged from 46 to 101%. Method detection limits for MBT, DBT, and TBT were 1.28, 0.39, and 0.24 ng/L, respectively. The major advantages of this technique are sensitivity, reduced analysis time, and a significant reduction in the amount of dichloromethane used. Results from the analysis of various surface water samples collected in New York are presented.