Application of SPE-HPLC-DAD and SPE-HPTLC-DAD to the analysis of pesticides in lake water

Abstract

Summary The objective of this paper is to present a new procedure for analysis of pesticides in water by use of solid-phase extraction (SPE) and high-performance chromatography with diode-array detector (HPLC–DAD) and high-performance thin-layer chromatography with diode-array scanning (HPTLC–DAD). Pesticides in lake water were enriched by solid-phase extraction (SPE) on C18/SDB-1, C18, C18 Polar Plus, and CN cartridges. SPE was used not only for preconcentration of the analytes but also for their fractionation. The analytes were eluted first with methanol then with dichloromethane. Methanol eluates were analyzed by HPLC–DAD, the dichloromethane eluates by HPTLC–DAD. The method was validated for precision, repeatability, and accuracy. In HPLC–DAD calibration plots were linear between 0.1 and 50.0 μg mL –1 for all pesticides, with correlation coefficients, r, between 0.9992 and 1.000. In HPTLC–DAD the best fit for the calibration plots was obtained when the calibration data were analyzed by second-degree polynomial regression. Calibration plots between 0.1 and 17 μg per spot were obtained for all pesticides; the correlation coefficients, r, were between 0.9974 and 0.9997. The limit of detection (LOD) was between 0.04 and 0.65 μg per spot for HPTLC–DAD and between 0.01 and 1.56 μg mL–1 for HPLC–DAD. The limit of quantification (LOQ) was between 0.12 and 1.92 μg per spot for HPTLC–DAD and between 0.04 and 4.72 μg mL –1 for HPLC–DAD.