Simutaneous Determination Of Three Butyltins By Wavelet-Partial Least Squares Enhenced Polarography

Butyltins were widely used as fungicides in agriculture, antifouling in ship paints, and stabilizers for PVC in plastics industry. Tributyltin (TBT) has been largely applied in ship paints to prevent alga and conch's cohesion. The toxicity of butyltins on organisms depends on their chemical species and TBT is the most toxic species. It also may have some effects on human being through the bioaccumulation of food chain.A computerized oscillographic polarography (Model JP-2) was devised to fulfill the simultaneous determination of three butyltins. The polarograms were transformed to digital signal by an analog-to-digital card , then the real-time data were collected and stored by a laboratory-written LabVIEW program.In a 0.4mol/L HAC-NaAC buffer solution(pH6.0), tributyltin, dibutyltin(DBT) and monobutyltin(MBT) each has a polarographic wave. The peak potentials of MBT and TBT were at -0.70V and -1.18V(vs. SCE). DBT had two polarographic waves with peak potentials at -0.78V and -0.88V(vs. SCE). The peak current and the concentration have linear correlation in the range of 0.6 μ g/ml~1.8 μ g/ml for MBT and 0.3 μg/mL~1.8 μ g/mL for DBT and TBT. Correlation coefficients were 0.993, 0.998 and 0.996. When there were two and/or three butyltins in the solution,severely interfered polarograms were observed and make it difficult to simultaneously determine each of butyltins by polarography. PLS2 was chosen to resolve the polarograms. Wavelet transform was selected to extract useful information for modeling PLS and polarographic data could be compressed from 520 points to 26 points. Simultaneous determination of monobutyltin, dibutyltin and tributyltin by polarography has been achieved successfully. The average recoveries were in the range of 96.2%~101.2% and the relative standard deviations (RSD) of MBT, DBT, TBT were 3.2%, 3.48% and 11.9% respectively.