Analysis of clozapine in its tablets using two novel spectrophotometric reactions targeting its tertiary amino group

Two simple spectrophotometric methodologies have been proposed and validated for the measurement of an atypical antipsychotic drug Clozapine (CLZ). Method A depends on interaction of CLZ with N-bromosuccinimide(NBS) resulting in formation of a yellowish orange colored product, measured at 320 nm. The linearity range was 5.0-70.0 μg/mL. Method B depends on condensation of the same drug with acetic acid mixed anhydride reagent producing a purple colored product, measured at 319 nm. The linearity range was 8.0-24.0 μg/mL. All parameters affecting the reaction condition (volume of both reagent, temperature, time and the different diluting solvents) were optimized. Both methods were successfully applied to assay CLZ in its pure form and tablets giving mean percentage recoveries of (98.87 ± 1.8 and 100 ± 1.7) for method A, and corresponding values of (98.6 ± 0.96 and 99.5 ± 1) for method B. Besides, the study of reactions stoichiometry was performed and the reaction mechanisms were proposed.