Speciation analysis of organotin compounds by capillary electrophoresis with direct ultraviolet absorbance detection

Organotin compounds (OTCs), particularly tributyltin, have been widely used as biocides in antifouling paints. These pollutants have been detected in many aquatic ecosystems, with highest concentrations in the marine coastal and lagoon environments; their widespread diffusion is due to their use in many activity sectors and their chemical characteristics. OTC are extremely toxic to a wide range of organisms, including humans; they are considered endocrine disruptors, as responsible for genetic, reproductive and metabolic disorders. Because of their persistence, there is increasing concern over their presence in the environment. The most commonly used separation techniques are liquid chromatography LC and gas chromatography GC, despite the need for derivatization of organotin compounds to more volatile species, one of the most critical steps in organotin analysis. Capillary electrophoresis (CE) could be an alternative technique of great potential because the organotin species can be separated without changing the actual chemical form of the species. In addition, CE has the advantages of high speed, high efficiency, relatively low cost and requires much smaller sample. Therefore, the aim of this study was the development of a CE method for the inexpensive and quick determination of organotin compounds (tributyltin TBT, dibutyltin DBT, monobutyltin MTB) using direct ultraviolet absorbance detection, although their lack of chromophore, by proper selection of acetate buffer, pH adjustment and organic modifier addition to the background electrolyte. Future studies will concern the improvement of sensitivity and the development of a preconcentration step, using new materials such as zeolite, in order to evaluate the applicability of the method to real environmental samples.