Sequential optimization of a flow injection spectrophotometric method for the assay of chlorpromazine in pharmaceutical preparations

A new simple flow injection spectrophotometric method for the assay of chlorpromazine using cerium(IV) in sulfuric acid media was developed. The oxidized form of the drug was monitored at the maximum absorbance of 526 nm. The optimum conditions were 0.035M sulfuric acid, 3.80 × 10^-3M cerium(IV), flow rate 4.85 ml/min, coil length 45 cm and sample size 110 mm³. Optimization was carried out by the modified simplex method. Response surface methodology was employed to investigate the ruggedness of the method. A sampling frequency of 120 hr^-1 was attained. Relative standard deviations for standard sample were usually less than 0.75. The method was applied to the determination of chlorpromazine in proprietary drugs and results were statistically compared with the official British Pharmacopoeia (BP) method.