DETERMINATION OF TRACE BUTYLTIN COMPOUNDS IN SEA-WATER BY GAS-CHROMATOGRAPHY ATOMIC-ABSORPTION SPECTROMETRY

A gas chromatography-atomic absorption spectrometric (GC-AAS) method has been developed for the determination of trace butyltin compounds in sea water. Aqueous butyltin compounds were reduced to the volatile hydride forms by NaBH4 and were extracted with dichloromethane simultaneously. The dichloromethane extract was concentrated under reduced pressure, followed by direct injection into the GC-AAS system for analysis. The butyltin species were separated with a 2-m glass column packed with 2% OV-101 on Chromosorb G HP (100-120 mesh). Following GC separation, each species was transferred into an electrothermally heated (800-degrees-C) quartz furnace for atomization. The tin atoms produced from individual butyltin compound were detected at 224.6 nm by an atomic absorption spectrometer. With a sea water sample (1 L), the detection limits (3-sigma) for monobutyltin, dibutyltin and tributyltin were approximately 20, 20 and 70 ng Sn L-1, respectively. The method has been applied to the analysis of trace butyltin compounds in the sea water of Keelung Harbor.