Effect of using selected information from HPLC-DAD and PLS in the elimination of interferences for the resolution of a complex pesticide mixture

Partial Least Squares (PLS) and Principal Component Regression (PCR) method s were applied to the simultaneous determination of a mixture of twelve pes ticides by high performance liquid chromatography (HPLC). Calibration model s at two different wavelengths were developed to resolve mixtures of the pe sticides with overlapping chromatographic peaks. The first model carried ou t at 205 nm, as first detector compromise wavelength, yielded satisfactory sensitivity and selectivity for estimation of the concentration of iprodion e, procymidone, triadimefon, and vinclozolin. The other model at 250 nm, as second detector compromise wavelength, was used for estimation of chloroth alonil, clorfenvinphos, fenamiphos, parathion-methyl, parathion-ethyl, and triazophos. However, two pesticides of the mixture, malathion and tebuconaz ole, showed bad prediction ability and were not determined, perhaps owing t o their low signal relative to the other compounds. Both calibration models were evaluated by predicting the concentration of independent test set sam ples, and were successfully applied to the determination of these pesticide s in groundwater samples. In all cases the PLS calibration method showed su perior quantitative prediction ability than the PCR method.