Chromatographic and Automated Spectrophotometric Determination of Some Antipsychotic Drugs in Pharmaceutical Products

Chromatographic and spectrophotometric methods for the quantitative determination of three antipsychotic drugs in pharmaceutical products were developed. The investigated drugs are quetiapine fumarate, olanzapine and risperidone. The flow injection analysis (FIA) method is based on the oxidation of these drugs by potassium permanganate in a basic medium. The resulting green color was monitored at 433 nm. Optimization of chemical and FI variables has been made. Under the optimized conditions, the sampling rate was about 80 injections/hour. The method is fast, simple and sensitive. For the chromatographic method, a reversed-phase Varian C8 column was used at ambient temperature. The mobile phase was a mixture of acetonitrile (ACN), acetate buffer and triethylamine (TEA), (60% ACN, 39.8% acetate buffer and 0.2% TEA, v/v/v), adjusted to pH = 4.7 with acetic acid. Tetrazolium salt was used as an internal standard. The absorption of the eluted compounds was measured using a variable-wavelength UV detector at 278 nm. The methods were applied successfully for the assay of three antipsychotic drugs in pharmaceutical products and no interferences were observed from the common excipients usually used. The proposed methods were validated for their accuracy and precision.