Determination of butyltin compounds in aqueous samples by gas chromatography with flame photometric detector and headspace solid-phase microextraction after in-situ hydride derivatization

A method for the extraction and determination of butyltin species in aqueou s samples by solid-phase microextraction (SPME) combined with a capillary g as chromatography-flame photometric detector (GC-FPD) is described. The but yltin species was converted to its hydride form by sodium tetrahydroborate (NaBH4) in a closed headspace vial prior to extraction. A laboratory-assemb led SPME device including a fused-silica fiber and a modified microsyringe protection part was used throughout the experiment. The extraction was an e quilibrium process that depended on the butyltin species partitioning betwe en the liquid phase and the fiber. When the equilibrium was reached, the fi ber was directly transferred to a GC column under the protection of a micro syringe, where the analyte was thermally desorbed inside the heated injecto r and subsequently, separated in a HP-1 capillary column and detected by a laboratory-made flame photometric detector using quartz surface-induced tin emission. The detection limits based on the signal equal to 3 times of the base-line noise were 0.2 mu g/L, 0.2 mu g/L, 0.1 mu g/L and 0.02 mu g/L fo r monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT) and tetrabutyltin (TeBT), respectively. The recovery ranged from 85% to 117%. The proposed m ethod has been applied to determination of butyltin species in Various aque ous samples.