RP-HPLC

A convenient, simple, accurate, precise and reproducible RP-HPLC method was developed and validated for the estimation of Linezolid in the bulk drug and pharmaceutical dosage form. The objective was achieved under optimized chromatographic conditions on Welchrom C18 isocratic column (250 mm × 4.6 mm, 5 μm) with Shimadzu LC-20AT Prominence Liquid chromatograph. The mobile phase was a mixture of acetonitrile: water 50:50 v/v, with apparent pH of 6.8. The separation was attained using an isocratic elution method with a flow rate of 1.2 mL/min at room temperature. The detection was made at a wavelength of 254nm by using UV- Visible detector.  The retention time for Linezolid molecule was found to be 2.813.The standard calibration plot was linear over a concentration range of 2-10 µg/mL with r2= 1 and the respective linear regression equation being y= 177.1x + 0.030.The limit of detection and limit of quantification were found to be 0.04µg/mL and 0.014µg/mL respectively. The amount of Linezolid presents in the bulk drug 99.81%and in the formulation 99.81% of the stated amount respectively. The method was validated statistically using the %RSD and the values are found to be within the limits. No interference peaks from Excipients and relative retention time indicated the specificity of the Method.  The recovery studies were performed and mean percentage recoveries were found to be greater than 99% with RSD less than 1.0%. So the proposed method was found to be simple, specific, linear, robust and reproducible. Hence this method was conveniently and easily applied for routine analysis of Linezolid in bulk drug and tablet dosage form.

A simple RP-HPLC compatible method for the injectable suspension dosage of combined medroxyprogesterone acetate and estradiol cypionate was developed and validated according to ICH and USP guidelines. The chromatographic separation was achieved by using the Zorbax Eclipse C18 column (50 mm×4.6 mm, 2.7 µm) with gradient elution technique at a flow rate of 1.0 ml/min. The UV detection was performed at 225 nm. The linearity of medroxyprogesterone acetate over the concentration range was 49.65 to 744.69 μg/ml and 10.15 to 152.28 μg/ml for estradiol cypionate respectively. The accuracy was evaluated by means of spike recovery method and the result showed in the range of 99.7% to 101.4% for medroxyprogesterone acetate and 98.6% to 101.8% for estradiol cypionate. The specificity of the method showed that the analyte was not interfered by the presence of co-formulated substances. The robustness of the study was found agreeable; hence it proves that the method was robust. The stability of the analyte was found stable for 24 hours. The developed method was successfully employed for the determination of combined medroxyprogesterone acetate and estradiol cypionate in injectable suspension dosage forms.

An isocratic reversed phase stability-indicating reverse phase high-performance liquid chromatographic (HPLC) assay method have been developed and validated for the determination of pentoxifylline in bulk drugs. Separation of pentoxifylline from the degradation products was carried out using an Inertsil ODS C18 (250cm x 4.6)mm,5u column  with  mobile phase consisting a mixture of  acetonitrile  and  KH2PO4 buffer (pH 4.0) in the ratio of (60:40v/v). The detection was carried out at wavelength 275nm. The developed method was validated with respect to linearity, accuracy (recovery), precision, system suitability, selectivity prove the stability indicating ability of the method.

A simple, accurate, precise and fast reverse phase, gradient RP-HPLC method was developed for the separation of telmisartan and hydrochlorothiazide in combination dosage form of Tablets. The method was carried out by using Kromasil, C18, 4.6 x 150mm, 5 μm enhanced polar selectivity column and mobile phase comprised of potassium dihydrogen phosphate buffer pH adjusted to 3.2 ± 0.5 with orthophosphoric acid and acetonitrile, and degassed under ultrasonication. The flow rate was 1.5 mL/min and the effluent was monitored at 225nm. The retention time of hydrochlorothiazide and telmisartan were 2.7 ± 0.5 and 7.3 ± 0.5 respectively. The method was validated as per ICH guideline. The proposed method is suitable for simultaneous determination of telmisartan and hydrochlorothiazide in pharmaceutical dosage form.