Development of LLE and SPE procedures and its applications for determination of olmesartan in human plasma using RP-HPLC and HPTLC

Two novel simple and rapid liquid-liquid and solid phase extraction methods have been developed for determination of olmesartan in human plasma using zidovudine as an internal standard. Liquid-liquid extraction from spiked human plasma samples was done using Dichloromethane: acetic acid (5.5: 0.5, v/v) solvent, while solid phase extraction was carried out on a DSC MCAX cartridge. For HPLC, the mobile phase consisted of water acetic acid pH 4.5 and methanol (25:75) at a flow rate of 0.5mLmin-1 in isocratic mode. The calibration curve was plotted with a concentration range 10gmL-1 to 60gmL-1. Recovery studies were carried out by LLE and SPE procedures with average recoveries 69.27% and 72.87%, respectively. For HPTLC the developing phase consisting of ethyl acetate methanol and acetic acid (8.0:2.0:0.05v/v/v) and detection was carried out on 269nm. The calibration curve was plotted over the concentration range of 200ng to 600ng. The average recoveries were 90.12% and 79.64% by LLE and SPE, respectively. The proposed method was validated as per US-FDA guidance.