Simultaneous determination of tartrazine and sunset yellow by derivative spectrophotometry and ratio spectra derivative

Two methods for determining Tartrazine and Sunset Yellow in mixtures by first derivative spectrophotometry and by first derivative of the ratio spectra are described. The procedures do not require any separation step. By the first method, the measurements are obtained in the zero-crossing wavelengths and the calibration graphs are linear up to 20 microg/ml of Tartrazine and up to 40 microg/ml of Sunset Yellow. The determinations of Tartrazine and Sunset Yellow are also done by the first derivative of the ratio spectra. The methods are applied for determining both compounds in four commercial food products.