Ion-pair high-performance liquid chromatographic determination of morphine and pseudomorphine in injections.

A stability-indicating HPLC procedure has been developed for the determination of morphine and its degradation product pseudomorphine in injection solutions. The reversed-phase chromatographic procedure uses an octadecyl-bonded column with a mobile phase of acetonitrile and aqueous buffer containing an ion-pair reagent. Chromatographic conditions are identified that enable the complete separation of morphine and pseudomorphine without peak deformation or splitting. The only sample preparation required is a simple dilution. The method is found to be precise and linear. The devised method has been applied to the determination of the content of morphine and pseudomorphine in injection solutions stored under normal conditions and after exposure to daylight or heating at 60 degrees C.