Bioanalytical Method Development and Validation of Esomepraole in Human Plasma by LCMS/Ms

A sensitive liquid chromatography-electro spray ionization mass spectrometry (LC-ESI-MS) method is developed and validated for rapid determination of Esomeprazole in human plasma. Rabeprazole was used as the internal standard (I.S). Human plasma (80 μl) was first alkalified with 200 ml of sodium bi carbonate (100 mM) and then extracted with 2 ml of Ethyl acetate by vibromax shaker for 15 min. The mixture was centrifuged at 4000 rpm for 15 mins. The supernatant was evaporated to dryness and the residue was reconstituted with water: 0.02% Diethylamine in methanol (3:7 v/v). Samples were separated by using a Gemini C₁₈ reversed phased column (50 mm×4.6 mm I.D, 5μ). Mobile phase consisted of Acetonitrile:water (pH:7.0 with Ammonia) [8:2 v/v]. Esomeprazole and internal standard were measured by electrospray ion source in positive selective ion monitoring mode. The good linearity ranged from 5 ng/ml to 1000 ng/ml and the lowest limit of quantification was 5 ng/ml. The extraction efficiency was approximately 73.4%. The quality control samples were stable when kept at room temperature for 6 hours, -70°C for 29 days and after three freeze- thaw cycles.