Simultaneous adsorptive voltammetric analysis of mixed colorants by multivariate calibration approach

Synthetic colorants, such as Amaranth, Sunset Yellow, Tartrazine and Ponceau 4R, have sensitivity adsorptive voltammetric waves in solution containing a phosphate-citric acid buffer and a potassium chloride supporting electrolyte (pH 5.7; I = 0.5 moll−1). The waves of these colorants, however, are seriously overlapped and it is difficult to determine them simultaneously without a preseparation. In this paper, voltammetric conditions for the analysis of up to four-component mixtures of colorant present at trace levels (0.03–0.20 μg ml−1) were investigated using adsorptive voltammetric approach at a hanging mercury drop electrode (HMDE). A serial of colorant mixtures were analyzed and the results were interpreted using ordinary least squares (OLS), principal component regression (PCR) and partial least squares regression (PLSR). In each case an orthogonally designed calibration set was used to facilitate predictions. The predicted results show that the multivariate calibration methods based on latent variables are more precise than those with ordinary least squares.