A simple, specific, accurate, rapid, inexpensive isocratic Reversed Phase-High Performance Liquid Chromatography (RP-HPLC) method was developed and validated for the quantitative determination of Amlodipine besylate and Hydrochlorothiazide in pharmaceutical tablet dosage forms and HPLC method was used for an in vitro dissolution study of tablets containing the above drugs. RP-HPLC method was developed by using Welchrom C18 Column (4.6 X 250 mm, 5 µm), Shimadzu LC-20AT Prominence Liquid Chromatograph. The mobile phase composed of 10 mM Phosphate buffer (pH-3.0, adjusted with triethylamine): acetonitrile (50 : 50 v/v).The flow rate was set to 1.0 mL.min-1 with the responses measured at 230 nm using Shimadzu SPD-20A Prominence UV-Vis detector. The dissolution test was performed using 900 mL of distilled water as the dissolution media at 50 rpm using an USP Apparatus II at 37°C. The retention times of Hydrochlorothiazide and Amlodipine besylate were found to be 3.373 minutes and 3.753 minutes respectively. Linearity was established for Amlodipine besylate in the range of 1-5 µg / mL with correlation coefficient 0.9995 and Hydrochlorothiazide in the range of 3-15 µg / ml with correlation coefficient 0.9996. The validation of the developed method was carried out for specificity, linearity, precision, accuracy, robustness, limit of detection, limit of quantitation. The developed method can be used for routine quality control analysis of Amlodipine besylate and Hydrochlorothiazide in pharmaceutical tablet dosage form.

A sensitive and selective liquid chromatographic-tandem mass spectrometric (LC/MS/MS) method was developed and validated for the trace analysis (>1 ppm level) of p-Toluenesulfonicacid, a genotoxic impurity, in acyclovir drug substances. The chromatographic separation was achieved on Symmetry C-18 (150 X 4.6mm, 3.5µm) column using a mobile phase consisting of 5 mM ammonium acetate and methanol (70:30 v/v) at flow rate of 0.4 mL /min. The API-4000 LC/MS/MS was operated on an electrospray in negative mode. The selected ion monitoring (SIM) mode was used during the analytical run and it is able to quantitate up to 1.5 ppm of p-Toluenesulfonicacid. The newly developed method was validated as per achieved on International Conference on Harmonization (ICH) guidelines