Determination of noscapine in plasma by liquid chromatography

A liquid chromatographic method has been developed for the determination of noscapine in plasma. Noscapine and the internal standard, papaverine, were extracted into methylene chloride by column extraction. The separation was performed on a straight-phase liquid chromatographic system using a mobile phase of hexane--methanol--chloroform--diethylamine. A high detection selectivity was obtained by UV detection at 310 nm. The precision of the method was 3.8% (standard deviation) at a level of 89 ng/ml and 9.5% (standard deviation) at 5.9 ng/ml. The selectivity of the analytical method was evaluated by comparing analytical results after isolation of extracts of plasma samples on reversed- and straight-phase liquid chromatographic systems.