Different Spectrophotometric Methods for Quantitative Determination of Benztropine Mesylate in Presence of Its Carcinogenic Degradation Product

AbstractThree simple, accurate, sensitive and selective spectrophotometric stability-indicating methods for determination of Benztropine Mesylate (BNZ) in the presence of its hepatotoxic and carcinogenic degradation product; Benzophenone (BPH); were developed and validated without preliminary separation. The developed spectrophotometric methods are; first derivative, first derivative of ratio spectra and ratio difference were developed for the determination of BNZ in the presence of BPH in pure form and in pharmaceutical formulation. The most important advantage of this work is that it is the first time to develop spectrophotometric methods for determination of BNZ and its carcinogenic degradation product. BNZ was subjected to stress degradation conditions (acid, alkaline and oxidation), and the obtained degradate was confirmed to be BPH. Calibration curves of these methods are linear over the concentration ranges of 5-20 and 3-20 μg mL−1for BNZ and BPH, respectively. Method (I); first derivative spectrophotometric method where BNZ was measured at 228.2 nm. Method (II); first derivative of ratio spectra spectrophotometric one where the overlapping spectra of BNZ and BPH were well resolved and BNZ was measured at peak amplitude 228.8 nm. Method (III); ratio difference spectrophotometric method which depends on measuring difference in peak amplitude values between two different wavelengths of the ratio spectrum at 224 and 234 nm for determination of BNZ. While BPH was determined by the first derivative at 245 NM without interference from BNZ. The proposed methods were successfully applied for determination of the studied drug in its pharmaceutical formulation. These methods were validated according to ICH guidelines. Results obtained by applying the proposed methods were statistically analyzed and compared with those obtained by reported one using Fand student’s t-tests showed no significant difference was obtained regarding both accuracy and precision.