DETERMINATION OF BUTYLTIN COMPOUNDS IN SEDIMENTS BY GC/MS AFTER THEIR CONVERSION TO METHYL DERIVATIVES

摘要

A selective and rapid procedure was developed for the determination of trace amounts of butyltin compounds in sediments by capillary gas chromatography with mass spectrometric detection. Analytes were isolated from the sediment samples by extraction with a methanolic solution of HCl (0.5 mol l(-1)) followed by reextraction into a hexane solution of tropolone (0.1%). The organotin compounds were converted to the nonpolar methyl derivatives by methylation with a Grignard reagent. The recovery was determined for each step of the procedure. This efficient separation method combined with the ion trap based mass detection ensures a high selectivity even for concentrations approaching the detection limit (0.15 pg for Bu3SnMe) in real sediments. Chemical ionization using acetonitrile as the reaction gas, exhibiting a similar sensitivity of determination and reducing the background level, can serve as a convenient alternative of detection for sediments heavily contaminated by organics. The method was applied to a set of real samples and validated by analysis of a certified reference material. [References: 14]