Resolution of overlapping peaks in HPLC with diode array detection by application of partial least squares calibration to cross-sections of spectrochromatograms

Because of the capacity of the diode array detector (DAD) in high performance liquid chromatography (HPLC), three-dimensional data can be easily generated in analytical laboratories. This allows new possibilities for the identification and quantification of solutes eluting from a chromatographic column. This paper deals with the application of a computer aided technique in the resolution of overlapping peaks by Partial Least Squares (PLS) calibration. This consists in performing cross-sections through the three-dimensional (A, λ, t) data matrix to increase the analytical information for each analyte. In this way, the sensitivity in the determination is maximized. The application of this technique in combination with the PLS-1 method offers a greater ability to resolve overlapped chromatographic peaks, and greater accuracy in quantification than the PLS-1 method performed by using chromatograms obtained at one selected wavelength. In order to demonstrate the validity and applicability of the method, it has been applied to the resolution of iprodione, procymidone, chlorothalonil, folpet and triazophos pesticide mixtures in ground water and soil.