Estimation

In pharmaceutical products the presence of impurity assures the quality. It is important to identify potential source of impurities. Estimation of impurities is done by variety of chromatographic and spectroscopic techniques either alone or combination with other techniques. These different methods for detecting and characterizing impurities with IR, TLC, HPLC, MASS, NMR, HPTLC etc.  

A reverse phase HPLC method is developed for the determination of Azilsartan medoximil and chlorthalidone in pharmaceutical dosage forms. Chromatography was carried out on a C18 column 4.6 x 100mm, 5µm, Make: BDS using a mixture of potassium Di hydrogen ortho phosphate buffer and acetonitrile (35:65 v/v) as the mobile phase at a flow rate of 1.0 ml/min. Detection was carried out at 273 nm . The retention time of Azilsartan Medoxomil and Chlorthalidone was 2.59±0.1 mins and 3.85±0.5 min respectively. The linearity was observed In range of 2.5-15 µg/ml and 10-60 µg/ml with a correlation coefficient of Azilsartan medoximil and chlorthalidone were 0.996 and 0.999.the proposed method was validated for its linearity, accuracy, precision and robustness. The proposed method was found to be simple, rapid, accurate and precise. It was found to be economical and suitable for simultaneous determination of Azilsartan Medoxomil and Chlorthalidone in pharmaceutical dosage form.

A reverse phase HPLC method is developed for the determination of Esomeprazole and Domperidone in pharmaceutical dosage forms. Chromatography was carried out on a C18 column [4.6 x 100mm, 5mm, Make: BDS] using a mixture of potassium di hydrogen ortho phosphate buffer and acetonitrile (65:35 v/v) as the mobile phase at a flow rate of 1.3 ml/min. Detection was carried out at 298 nm .The retention time of Domperidone and Esomeprazole was 2.788 min and 3.485 min. The linearity was observed In range of 50-130 µg/ml and 60-140 µg/ml with a correlation coefficient of Domperidone and Esomeprazole were 0.999 and 0.999.the proposed method was validated for its linearity, accuracy, precision and robustness .The proposed method is simple, accurate, precise, and reproducible hence it can be applied for routine quality control analysis of Esomeprazole and Domperidone in pharmaceutical dosage form.

In this study, a simple, sensitive and highly accurate ultraviolet spectrophotometric method has been developed and validated for determination of atenolol in bulk and pharmaceutical formulations. The method is based on the measurement of the absorbance of atenolol solution in methanol: phosphate buffer pH 6.8 (10:90) at 224 nm in the wavelength range of 200 - 400 nm. Beer’s law was obeyed in the concentration range of 5-25 µg/mL. The slope, intercept and correlation coefficient were also calculated. Results of percentage recovery shows that the method was not affected by the presence of common excipients in tablets. The developed method was validated in terms of accuracy, precision, linearity, limit of detection, limit of quantification which proves suitability of proposed method for routine estimation of atenolol in bulk and pharmaceutical formulations.

An accurate and precise high performance liquid chromatographic method was developed for quantitative estimation of bosentan in tablet dosage forms. Chromatographic separation of the drug was achieved on a Kromasil C18 column (150 x 4.6 mm; 5µ) by eluting with a mobile phase consisting of phosphate buffer (pH 4.0) and acetonitrile (30:70 v/v) at a flow rate of 1.0 mL/min. The drug in the eluate was monitored by U V detection at 270 nm. The retention time obtained for the drug was 3.54 min. The calibration curve plotted was linear over the range of 25-175 µg/mL of the drug. The validation of the method was done following the ICH guidelines. The proposed method could be applied for determination of bosentan in its tablet dosage forms without any interference from excipients. The method is suitable for routine quality control analysis of bosentan formulations.

The aim of present work was to develop an accurate, precise, reproducible and economical UV spectrophotometric method for estimation of Loratadine. This method was based on area under curve of UV spectrum between 241 to 251 nm and validated as per ICH guideline Q2 (R1). The method has followed linearity in the range of 5-30µg/ml. The value of correlation coefficient was 0.999. Satisfactory values of Percent relative standard deviation for the intra-day and inter-day precision indicated that method is precise. Results of the recovery studies (99.66 % to 99.95 %) showed accuracy of the method. LOD and LOQ were calculated as 0.581 µg/ml and 1.935 µg/ml, respectively. The developed method can be used for routine estimation of Loratadine in bulk and tablet dosage forms.

A simple, precise and accurate RP-HPLC method was developed and validated for rapid assay of Dosulepin tablet dosage form. Isocratic elution at a flow rate of 1mL/min was employed on a symmetry Chromosil C18 (250x4.6mm, 5µm in particle size) at ambient temperature. The mobile phase consisted Methanol: Acetonitrile: 0.01M Phosphate buffer in the ratio of 55:20:25 (v/v/v). The UV detection wavelength was 230nm and 20 μL sample was injected. The retention time for Dosulepin was 3.46min. The percentage RSD for precision and accuracy of the method was found to be less than 2%. The method was validated as per the ICH guidelines. The method was successfully applied for routine analysis of Dosulepin tablet dosage form and bulk drug.

An accurate, precise and reproducible high performance liquid chromatographic method was developed for quantitative estimation of telmisartan in bulk drug samples and tablet dosage forms. Chromatographic separation of the drug was achieved on a Kromasil C18 column (150 x 4.6 mm; 5µ) using a mixture of phosphate buffer (pH 4.0) and acetonitrile (40:60 v/v) as the mobile phase at a flow rate of 1.0 mL/min. Under optimized conditions, the retention time of the drug was found to be 2.887 min. Good detecting sensitivity for the analyte was observed at 224 nm. The quantitation calibration curve for the drug was linear over the range of 20-60 µg/mL. The performance of the proposed method was validated as per ICH guidelines. The method was proved to be suitable for the estimation of telmisartan in tablet dosage forms. Key words: Telmisartan, Estimation, Tablets, HPLC.