DEVELOPMENT AND EVALUATION OF AN HPLC-DAD METHOD FOR DETERMINATION OF INDIGOTINE IN SOFT DRINKS

According to the Directive 94/36/EC of the European Union (EU), quantities of synthetic colorants added to foods are restricted by upper limits and, therefore, reliable methods for their quantification have to be established. Indigotine is the common name for uncertified FD&C Blue No. 2 and it is a blue food color, water soluble. In this paper, the operational parameters that shall lead to the development of a new analysis method of indigotine in soft drinks have been studied; the technique used is the liquid chromatography together with diode array detection. It has been tried to validate the analysis method settled, in terms of sensitivity, linearity range, reproducibility, repeatability, and robustness. The indigotine in the sample is separated on a C18 reversed phase chromatography column, diode array detected at 608 nm and quantified with a calibration graph. The method provides stable retention times and a detection limit of 0.03 mg/L indigotine at a signal to noise ratio of 3.