This paper shows the simultaneous electrochemical determination of dypirone (DIP) and paracetamol (PAR) by differential pulse voltammetry technique (DPV) using an unmodified carbon paste electrode. Because of the overlapping of the voltammetric peaks of DIP and PAR, the multivariate calibration methodology based on Partial Least Square Regression (PLSR) was proposed. The data pre-treatment used in this process was mean centering and to choose the principal component number a cross validation procedure was used (leave-one-out). Four principal components were necessary to obtain the lowest PRESS (Prediction Residual Error Sum of Squares). The statistics showed that this model explains approximately 95.5% of the variance from the data set. Using this model, high correlation between real and predicted concentrations was observed. However, for low concentrations of PAR the relative error increased to 25%. Comparing RMSEP (Root Mean Square of Error Prediction) between PAR and DIP, it was observed that it was lower for DIP probably due to higher analytical information in the voltammograms for this analyte when compared to the electrochemical process of PAR, which presented only one potential peak due to its irreversible oxidation.
paracetamol; dypirone; carbon paste electrode; differential pulse voltammetry; multivariate calibration methodology
