TLC-Spectrophotometric Determination of Sudan in Blusher and Eye-Shadow

Sudan in blusher and eye shadow was separated by TLC and determined by spectrophotometry. The sample was extracted ultrasonically with n-hexane. A mixture of sodium cellulose carboxymethylate and silica gel with definite ratio was used as adsorbent. A mixture of n-hexan, acetone and ethyl acetate with the ratio of 100 to 6 to 8 was used as developing solvent. Definite amounts (in μL) of sample solution and standard solution of sudanⅢ were spotted simultaneously onto the chromatographic plate and developed upward with the developing solvent. Based on the values of Rf and comparison between the colored spots of sample and standard sudan solution, detection of sudanⅢ in the sample was performed. Then the colored spot of the sample together with spot of blank silica gel located at same level with the spot of the standard was scraped off the plate and dissolved in 5.0 mL of n-hexane. Absorbance of the solution was measured at 498 nm with 1 cm absorption cell, and content of sudan Ⅲ and Ⅳ in the sample was found from the calibration curve having the linearity ranges within 30 mg·L-1 and between 5.0 to 30 mg·L-1 respectively, with detection limit (3s/k) of 0.05 mg·L-1. Recovery was tested by addition of standard solution of sudanⅢ and Ⅳ, giving results of recovery ranged from 93.7% to 97.6%.