Abstract
A simple, selective, and precise reversed-phase HPLC method with "diode array" detection has been developed, enabling separation and quantification, in a single run of tartrazine (E 102), amaranth (E 123), erythrosine (E 127) and indigotine (E 132) in soft drinks. HPLC was performed with a Surveyor Thermo Electron system and the reversed phase chromatographic separation was achieved at 30 °C, using a DS Hypersil C18.5 ?m column and a mobile phase made of 100 mM sodium acetate buffer and acetonitrile. Through optimization studies they were established: the gradient program of the elution, the injected volume 5 µL, the flow rate of the mobile phase 1mL/min, the duration of the analysis being 30 min. The synthetic colorants were detected by absorbance at ? = 430 nm for tartarzine, ? = 520 nm for amaranth and erythrosine and ? = 608 nm for indigotine. The method was validated in terms of sensitivity, linearity range, reproducibility, repeatability, analytical recovery and robustness.