SIMULTANEOUS DETERMINATION OF OMEPRAZOLE AND ITS METAL COMPLEXES BY REVERSED-PHASE HIGH PERFORMANCE LIQUID CHROMATOGRAPHY IN PHARMACEUTICAL FORMULATIONS

A sensitive, precise, selective and accurate reversed-phase high-performance liquid chromatographic (rphplc)method has been developed for the simultaneous determination of omeprazole in risek® capsules.omeprazole and the internal standard, diazepam, were separated by shim-pack clc-ods 0.4 × 25 cm, 5mm particle size column. the mobile phase was methanol-water (80:20, v/v), pumped isocratically at ambient temperature. analysis was run at a flow rate of 1.0 ml/min at a detection wave length of 302 nm.the method was specific and sensitive with a detection limit of 3.5 ng/ml at a signal-to-noise ratio of 4:1.the limit of quantification was set at 6.25 ng/ml. the calibration curve was linear over a concentration range of 6.25-1280 ng/ml. precision and accuracy, demonstrated by within-day, between-day assays, and inter-operator assays were lower than 10%. the in vitro availability of omeprazole in presence of manganese, cobalt, nickel, copper and zinc was studied by this method. recovery of omeprazole inpresence of various metals was from 41% to 74%.