Titrimetric and spectrophotometric determination of acetylenic hypnotics, using brominating agents

Titrimetric and spectrophotometric titration methods are described for the quantitative determination of acetylenic hypnotics ethchlorvynol, ethinamate, and meparfynol carbamate as pure substances and in dosage forms. The methods involve the use of different brominating agents. A known excess of the reagent is added and, after the specified time, the residual reagent is determined iodometrically. These procedures permit semimicro determination (1-20 mg) of the drug. Recoveries ranged from 98.48 +/- 0.76 to 102.74 +/- 2.60%. The procedures have been successfully applied to pharmaceutical dosage forms; the results agree well with those for compendial methods.