SENSITIVE ASSAY FOR VERAPAMIL IN PLASMA USING GAS-LIQUID-CHROMATOGRAPHY WITH NITROGEN-PHOSPHORUS DETECTION

A sensitive gas-chromatographic method for quantitative analysis of ve rapamil in human plasma is described. The method involves a single ext raction procedure, followed by separation on a capillary column and de tection with a nitrogen-phosphorus detector. The detection limit, base d upon an assayed plasma volume of 0.5 ml, is 2 ng/ml. The standard cu rve is linear in the concentration range of 2 to 1000 ng/ml. The recov ery of verapamil by pentane-isopropanol extraction was found to be 95% . Zipeprol is used as the internal standard. No interference from drug s needed for the associated cancer therapy has been found. Serum verap amil concentrations are determined by this method in fourteen cancer p atients undergoing treatment with adriamycin.