Development of a simple method for the determination of toluene extractable organotin by electrothermal atomic absorption spectrometry and its application to effluent analysis

Abstract

Toluene extractable organotin compounds in two sewage effluents and a complex, simulated effluent were determined at sub-ppb levels. The technique involves the acidification of the sample with glacial acetic acid, followed by its extraction into a small volume of toluene (a concentration factor of 100). The extract was then analysed by Zeeman graphite furnace electrothermal atomic absorption spectrometry (ETAAS) with an isobutyl methyl ketone solution of Pd as a modifier. At low levels of analyte, the extract was concentrated by evaporation of the toluene prior to analysis by ETAAS. The limit of detection (LOD; 3σ)(no evaporation of the extract) in the sewage effluents was 40 ng l^–1(as Sn), whilst for the complex, simulated effluent, it was 80 ng l^–1. The degradation in LOD was caused by the larger volume of toluene extraction solvent that was required to overcome formation of an emulsion with the complex effluent. The average recoveries of spiked, simulated, complex effluent (0.4 µg l^–1) were 102 ± 8.0%. The technique should be applicable to almost any water sample. The preparation of a reproducible, complex, simulated effluent for performance testing is described.