A simple, precise and reproducible reverse phase, isocratic high performance liquid chromatographic method was developed and validated for the quantitative determination of Vancomycin in blood plasma. The quantification was carried out using a HPLC system consisted of a Jasco UV- 975 intelligent UV visible detector, Jasco; PU-980 intelligent HPLC pump, Hypersil BDS C18 ; 150 mm x 4.6 mm , Clarity lite data apex 2003 software, REMI centrifuge machine (electrometer corporation);Model-R8C, with a mobile phase consisting of 10% acetonitrile in a 25 mmol/L or 50 mmol/L phosphate buffer in pH 7.0 and pH 3.2, at a flow rate of 1.0 and 1.5 ml/min ,detection wavelength were used at 229 and 270 nm. The method was validated and developed for selection of suitable Internal Standards, linearity, accuracy, robustness and solution stability. The linearity of the proposed method was investigated in the range of 5-100 μg /ml, R2 = 0.995 and 0.997 for reference standard vancomycin solution and in blood serum without any internal standard respectively and 0.998 with ondanosatrone when it was used as a I.S. The solution stability of vancomycin was studied at pH 7.0 and pH 3.2 under the same ionic strength condition at 37oC. A stability indicating HPLC method specific for vancomycin was developed and validated for use in the research. The proposed method was developed to apply for the analysis of vancomycin in bulk forms and also, the method was extended for determination of various pharmacokinetic parameters of vancomycin from in vivo blood plasma serum
