Simultaneous spectrophotometric determination of phenilpropanolamine HCL, caffeine and diazepam in tablets

A rapid, reliable and specific UV spectrophotometric method was developed to determine Phenilpropanolamine Hydrochloride (I), Caffeine (II) and Diazepam (III) formulated in tablets. This method was validated and compared with a liquid chromatography (LC) procedure used for the simultaneous quantitative analysis of the drugs. The established linearity ranges by both methods for compounds I, II and III were 0.36-0.88, 0.012-0.028 and 0.036-0.084 mg/ml, respectively. The correlation coefficients by HPLC were r(I)(2)=0.997, r(II)(2)=0.999, r(III)(2)=0.999 and by the UV spectrophotometric method were r(I)(2)=0.998, r(II)(2)=0.996, r(III)(2)=0.999. LC and UV methods showed excellent precision and accuracy. As regards precision, LC showed CV values range of 0.2-0.9 and UV 0.15-0.72. On the other hand, accuracy was obtained with CV values range of 0.1-1.8 and 0.32-1.11 for LC and UV, respectively. The recoveries of I, II and III were >98.04% for both methods over the linear range. The UV and HPLC methods have been successfully used to determine the I, II and III content in tablets of different origin.