HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC METHOD FOR THE SEPARATION ANDQUANTIFICATION OF SOME PSYCHOTHERAPEUTIC BENZODIAZEPINES OPTIMIZED BYTHE MODIFIED SIMPLEX PROCEDURE

An accurate high performance liquid chromatography method for the sepa ration and quantification of a solution mixture of nitrazepam, diazepa m and medazepam and medazepam was developed. The modified simplex prog ram has been utilized for the optimization of the chemical and chromat ographic parameters using the chromatographic response function as the quality criterion and a photodiode array as a detector. The separatio n was achieved in 2 min using a 20 cm long, 4.6 mm diameter Lichrosorb C18 reverse phase column. A 5 mu l solution mixture containing 10 ppm of each drug was injected into a mobile phase containing 89:11 v/v ac etonitrile: acetate buffer and a flow rate of 3.44 mi min(-1) was foun d to be optimal. The method was found to be suitable for the determina tion of these compounds in proprietary drugs without suffering interfe rences.