OPTIMIZATION OF COMPREHENSIVE SPECIATION OF ORGANOTIN COMPOUNDS IN ENVIRONMENTAL-SAMPLES BY CAPILLARY GAS-CHROMATOGRAPHY HELIUM MICROWAVE-INDUCED PLASMA EMISSION-SPECTROMETRY

The potential of the microwave-induced plasma atomic emission detector for capillary gas chromatography (GC-AED) as a tool for the speciation of organotin compounds in environmental samples is studied. The operational variables are optimized for chromatographic resolution and detection limits. A comprehensive method for the determination of mono-, di-, tri-, and some tetraalkylated organotin compounds in water and sediments by GC-AED is developed. Ionic organotin compounds are extracted as diethyl dithiocarbamates into pentane and, after its evaporation, dissolved in a small volume of octane and derivatized by pentylmagnesium bromide to give the solution of gas chromatographable species. The absolute detection limit is about 0.05 pg (as Sn), and the calibration graph is linear over three decades. The analytical response is independent of the elution temperature of the compound allowing for internal standard calibration. The accuracy of the method developed is confirmed by independent analysis by GC-AAS. A method to determine the empiric formula of the compounds detected is proposed.