Журнал хроматографии и методов разделения
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Use of Polydimethylsiloxane Preconcentration Sorbent for the Analysis of Organotins in Water Samples

Cavalheiro J, Tessier E, Baltrons O, Donard OFX and Monperrus M

Organotin compounds were extensively used as powerful biocides in anti-fouling paints and pesticide formulations, particularly tributyltin (TBT), and are recognized as priority pollutants by the european European Water Framework Directive (WFD). Environmental Quality Standard set by the WFD for TBT is fixed at 0.2 ng.L-1 for water samples which impose the use of very sensitive analytical techniques to perform such analysis. GC-ICP-MS is the only analytical technique able to achieve such low concentration level, but the expensive equipment requires also qualified personnel to operate, so not all routine laboratories can afford to use it. Preconcentration methods are therefore a good alternative to obtain a more concentrated and cleaner sample extract and later use an easier and affordable analytical technique like GC-MS. In this work, a new method to analyse organotin compounds in water samples using a preconcentration step with polydimethylsiloxane sorbents was developed and validated. The analytical method exhibited linearity higher than 0.9967 for all compounds. For butyltin compounds, LOQ were between 5.7-20.1 pg.L-1 with precision below 8%. For methyltin compounds, LOQ were between 26.9-106 pg.L-1 with precision below 22%. Matrix effects were evaluated for simulated synthetic estuarine and river waters and was then applied to real estuarine and river water samples. Very good recoveries were obtained for butyltins ranging between 87% and 131%. Methyltins, however, exhibited recoveries between 26% and 118% as a result of matrix effect no accurately corrected by the quantification by external calibration.