Speciation of Trace Di- and Triorganotins in Water by Ion-Exchange HPLC-GFAA

A broad range of organotins representing current industrial and environmental interests were speciated in trace quantities by a combination of an element-specific graphite furnace atomic absorption (GFAA) detector coupled with high performance liquid chromatography (HPLC) employing commercial, bonded-phase, strong cation-exchange (SCX) columns. Optimization of SCX column parameters was characterized in terms of efficiency and resolution, to provide examples for separation of organotins, RnSn(4-n)+, by class (n = 2,3), functionality (R = aryl, alkyl, alicyclic), and as geometric isomers (R = n-butyl vs. i-butyl; benzyl vs. 4-tolyl). This permitted a novel application of molecular substituent parameters available from the literature in a linear relationship to the free energy term, Ink. Means for predicting optimal chromatographic conditions or for identifying unknown R groups were shown. SCX column performance varied for individual organotin analytes, as did HPLC-GFAA system detection limits (95% confidence limit) in the range 5 to 30 ng (as tin). Applications of the method to current problems involving direct speciation of organotins in field samples from marine antifoulant leachates were described.