SELECTION OF CALIBRATION MIXTURES AND WAVELENGTHS FOR DIFFERENT MULTIVARIATE CALIBRATION METHODS

A comparative study to select calibration mixtures and wavelengths in multivariate calibration methods was made. The methods studied were cl assical least squares (CLS), inverse least squares (ILS), partial leas t squares (PLS), principal component regression (PCR) and Kalman filte r. For each method the calibration samples were selected from a total random population of 37 calibration standards, taking into account the standard error of prediction (SEP). The selection of analytical wavel engths for each method was carried out using different criteria: the c ondition number for CLS and Kalman filter methods, the signal-to-noise (S/N) ratio and the condition number for ILS method, and all the prev ious criteria and the full spectrum for PCR and PLS methods. The best results were obtained using the condition number as criterion to selec t the analytical wavelengths. The study has been applied to the spectr ophotometric determination of four priority pollutant chlorophenols.