Simultaneous determination of tartrazine, sunset yellow and allura red in commercial soft drinks by multivariate spectral analysis

The spectral resolution of ternary mixtures of the dyes, allura red (red-40 ), sunset yellow (yellow-6) and tartrazine (yellow-5) was achieved by parti al least squares (PLS-I and PLS-2) and principal component regression (PCR) multivariate calibration. The absorption and first-derivative absorption s pectra of ternary synthetic standard mixtures were used to perform the opti mization of the calibration matrices by PLS and PCR methods. The effect of the spectral region used during the calibration was studied a nd showed to have an important effect on the number of factors used to mode l the studied analytes. Method performance in the concentration predictabil ity of different synthetic standard samples by the application of the vario us chemometric approaches are discussed and compared by ANOVA. The proposed methods were applied satisfactorily to the determination of allura red, su nset yellow and tartrazine in several commercial softdrinks and the results were compared to a HPLC standard method developed in this laboratory. Whil e no difference was observed when analyzing synthetic mixtures of the dyes, the use of derivative spectra together with multivariate calibration gives results comparable to HPLC when analyzing beverage samples. For the first time a robust analysis method in which sample preparation is minimal when d ealing with samples with high matrix interference is developed. The present work shows areal practical application of derivative spectra in multivaria te calibration.