RESOLUTION OF OVERLAPPING PEAKS IN HPLC WITH DIODE-ARRAY DETECTION BYAPPLICATION OF PARTIAL LEAST-SQUARES CALIBRATION TO CROSS-SECTIONS OFSPECTROCHROMATOGRAMS

Because of the capacity of the diode array detector (DAD) in high perf ormance liquid chromatography (HPLC), three-dimensional data can be ea sily generated in analytical laboratories. This allows new possibiliti es for the identification and quantification of solutes eluting from a chromatographic column. This paper deals with the application of a co mputer aided technique in the resolution of overlapping peaks by Parti al Least Squares (PLS) calibration. This consists in performing cross- sections through the three-dimensional (A, lambda, t) data matrix to i ncrease 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 abili ty to resolve overlapped chromatographic peaks, and greater accuracy i n quantification than the PLS-1 method performed by using chromatogram s obtained at one selected wavelength. In order to demonstrate the val idity and applicability of the method, it has been applied to the reso lution of iprodione, procymidone, chlorothalonil, folpet and triazopho s pesticide mixtures in ground water and soil.