RESOLUTION OF PHENOL, O-CRESOL, M-CRESOL AND P-CRESOL MIXTURES BY EXCITATION FLUORESCENCE USING PARTIAL LEAST-SQUARES (PLS) MULTIVARIATE CALIBRATION

Determination of phenol, o-cresol, m-cresol and p-cresol has been carr ied out in mixtures of up to four components by recording excitation f luorescence spectra between 210 and 285 nm with an emission wavelength of 298 nm. The excitation-emission spectra of these compounds are str ongly overlapped, which does not permit their direct determination wit hout previous separation by conventional methodologies. Here, a method is proposed for the determination of these chemicals by the use of a full-spectrum multivariate calibration method, partial least squares ( PLS). The experimental calibration matrix was designed with 18 samples . The concentrations were varied between 100 and 900 mu g l(-1) for ph enol, 150 and 900 mu g l(-1) for o-cresol and from 80 to 800 mu g l(-1 ) for m- and p-cresol. The cross-validation method was used to select the number of factors. To check the accuracy of the proposed method, t he optimized model, obtained using PLS-1, was applied to the determina tion of these compounds in natural water and soil samples previously s piked with different amounts of each chemical.