RAPID SPECTROPHOTOMETRIC METHOD FOR DETERMINING ERYTHROSINE, AMARANTHAND TARTRAZINE IN TERNARY MIXTURES

A very simple spectrophotometric method using measurements at zero-cro ssing wavelength is described for resolving ternary mixtures of the fo od colorants Erythrosine (E-127), Amaranth (E-123) and Tartrazine (E-1 02). Calibration graphs are linear up to 14 mg/L of Erythrosine and 28 mg/L for Tartrazine and Amaranth. RSD of 0.80, 0.85 and 1.84 % were o btained for nine standards of 8 mg/L of Erythrosine, 8 mg/L of Tartraz ine and 8 mg/L of Amaranth, respectively. Detection limits of 0.052, 0 .934 and 0.123 mg/L were obtained for Erythrosine, Tartrazine and Amar anth, respectively. This method was satisfactorily used for determinin g synthetic mixtures of these colorants in different ratios and it was successfully applied to a commercial product containing the three dye s; no separation step is required. The results were compared with thos e obtained by liquid chromatography and very similar values were found by both methods.