Quantitative determination for cocaine HCl in synthetic binary mixtures by using spectrophotometric methods

In this study, two different spectrophotometric methods (Vierordt and Absorbance ratio method) were applied for Cocaine HCl - Procaine HCl and Cocaine HCl-Caffeine in synthetic binary mixtures. The result of the spectrophotometric methods were then compared to the results obtained from an HPLC method. In the Vierordt method; A(1)(1) values (% 1.1 cm) were determined at 232, 221 and 272 mi in methanol for Cocaine HCl (I), Procaine HCl (II) and Caffeine (III), respectively. The ratio of All values and total absorbance values were applied to the equation which was developed by Vierordt. In the absorbance ratio method, 224 and 247 nm were chosen as isobestic points and the total absorbances were measured at 232, 296 and 272 nm in methanol. Absorbance ratios of 232/247 and 296/247 were used in the regression equation for I-II, also absorbance ratios of 231/224 and 272/224 were used in the regression equation for I-III synthetic binary mixtures. In the HPLC method, mu Bondopack C-18 10 m mu column and methanol-water-phosphoric acid 1%-hexylamine (75:175:250:3,5) were used as mobile phase and antipyrine was chosen as internal standard for quantitative determination. The linear concentration areas were found in a range of 2-16 mu g/mL, in both spectrophotometric methods. The linear concentration interval was calculated between 2-25 mu g/mL in the HPLC method. RSD values were found to be 0.83- 1.19- 1.33 % for I, 1.05- 1.6- 0.94 % for II, 1.53-1.49-0.88% for III in Vierordt, Absorbance ratio and HPLC methods, respectively.