Simultaneous spectrophotometric determination of mixtures of food colorants

Mixtures of food colorants, containing tartrazine, sunset yellow, ponceau 4R, amaranth and brilliant blue, were simultaneously analyzed with spectrophotometry without previous chemical separation. The data obtained from experiments were processed by chemometric approaches, such as classical least squares (CLS), principal component regression (PCR), partial least squares (PLS) and iterative target transformation factor analysis (ITTFA), using the normal absorbance spectra and first- and second-derivative absorbance spectra. Sixteen mixtures of colorants with five-combination were evaluated and the results obtained by the application of the different chemometric approaches were discussed and compared. It was found that ITTFA often afforded better precision than those of CLS, PCR and PLS, and calibrations based on first-derivative data provided some advantages for all these four methods. The proposed method was applied satisfactorily to the determination of colorants in several commercial food products.