Determination of food colorants in pharmaceuticals by enrichment prior to spectrophometric and HPLC methods

Synthetic colorants are used worldwide in food, medicine, cosmetics, etc. Many of their kind are widely used because of their low price, high effectivity, and good stability. Some of these substances doses a potential risk to human health and, in contact with some drugs, they can cause allergic and asthmatic reactions. A cloud point extraction process using micelles of CTAB and Triton X-100 for preconcentration and spectrophotometric determination of Erythrosine, Quinoline Yellow and Indigotine in pharmaceuticals was developed. The effect of different parameters such as concentration of surfactant, salt concentration, pH, temperature and incubation time on the cloud point extraction of colorants were studied in detail and set of optimum conditions were established. The extracted surfactant rich phase is diluted with acetone and its first derivative absorbance value is measured at 497 nm for E, 408 nm for QY and 637 nm for IC by a spectophotometer. A lineer calibration curve in the range of 1-6 µg/mL of E, 1-6 µg/mL of QY and 0,3-1,8µg/mL of IC were obtained. The method was validated as regards its selectivity, linearity, precision, accuracy, limit of detection (LOD) and quantification (LOQ). LOD values of colorants were 0,031 µg/mL for E, 0,057 µg/mL for QY and 0,048 µg/mL for IC. In the case of LOQ values of colorants were 0,103 µg/mL for E, 0,190 µg/mL for QY and 0,160 µg/mL for IC. Results of cloud point extraction were tested by comparing the results with the other developed process of HPLC. A C18 stationary phase was used and the mobile phase contained acetonitrile-methanol (1:1, v/v) mixture and 0,1 M ammonium acetate buffer solution at pH 7. Successful separation was obtained for all the compounds using an optimized gradient elution within 30 min. The diode-array detector was used to monitor the colorants between 350-800 nm. Two separate methods; spectrophotometric and HPLC methods for the determination of the colorants (E, QY and IC) were developed and in terms of accuracy and precision of the findings of these methods were compared with 95% confidence level with the help of t and F tests and the applicable methods were evaluated. F value of the confidence level, three trial values of the table is small. However t value of the confidence level, three trial values of the table is big. Keywords: Synthetic colorants, Erythrosine (E), Quinoline Yellow (QY), Indigotine (IC), Cloud Point Extraction, CTAB, Triton X-100, Spectrophotometer, Pharmaceutical, HPLC, Diode-Array Detector.