forced degradation studies.

A Stability indicating isocratic liquid chromatographic method with UV detection at 255 nm is described for simultaneous determination of sofosbuvir and velpatasvir  in its bulk and tablet dosage form. Chromatographic separation of two drugs was achieved on a YMC column (4.6×15mm,5 ) using a mobile phase consisting of a binary mixture of acetonitrile and 0.025M KH2PO4  adjusted to pH3..0 with orthophosphoric acid in ratio 50:50. The developed Liquid Chromatographic method offers symmetric peak shape, good resolution and reasonable retention time for both drugs. Linearity, accuracy and precision were found to be acceptable over the concentration range of 50-250 µg/ml for velpatasvir and 200-1000µg/ml for sofosbuvir and R2 found to be 0.999. Accuracy was measured via recovery studies and found to be acceptable, and the percentage recoveries were found in the range of 97-103%.Method precision results obtained are 0.1%RSD for sofosbuvir and 0.8%RSD for velpatasvir. Forced degradation studies were also conducted, and the drugs were subjected to various stress conditions such as acid hydrolysis, base hydrolysis, oxidative, photolytic and thermal degradation. The proposed method was successfully validated and applied for the quantitative estimation of these drugs in both bulk and tablet dosage forms. The LC method can be used for the quality control of formulated products containing sofosbuvir and velpatasvir.

A simple and sensitive high performance thin layer chromatography (HPTLC) method has been developed for the quantitative estimation of Donepezil HCL in its bulk and tablet dose tablet formulation (5 mg). Donepezil HCL was chromatographed on silica gel 60 F254 TLC plate using  methanol : toluene (2:8, v/v) as mobile phase. Donepezil HCL showed Rf value 0.54 + 0.008 and scanned at 245 nm using a camag TLC scanner 3. The method was validated in terms of linearity (100 – 800 ng/spot), precision (system precision = 0.0123 and method precision = 0.0084), accuracy (100.3 ± 0.76) and specificity. The limit of detection and limit of quantification for Donepezil HCL were found to be 1.72 ng/spot and 2.07 ng/spot, respectively. The developed method was successfully used for the assay of Donepezil HCL tablet formulation. This method also contain forced degradation studies for standard and tablet. The method was found to be simple, sensitive, specific, accurate and precise and can be used for the routine quality control testing of Donepezil HCL in tablet dosage form.

A simple, accurate and stability indicating high performance liquid chromatographic (HPLC) method was developed for the simultaneous estimation of Torsemide and Spironolactone in combined dosage form. Isocratic RP-HPLC separation was achieved on Kromasil RP- C18 column (250mm×4.6mm; 5µm) using methanol: acetonitrile: water in the ratio of 50:30:20 (v/v), pH6.8, at flow rate of1.0ml/min at ambient temperature. Quantization was achieved by UV detection at 235nm over the concentration range of 10-60μg/ml for torsemide and 25-150μg/ml for spironolactone with percentage recoveries of range 99.688-101.792 and 98.282-101.811for torsemide and spironolactone respectively. Different stress degradation studies like acidic, alkaline, peroxide, thermal etc were measured for both standard drugs and results found that the stress degradation conditions doesn’t affect the elution of the both the drugs and hence the developed method was found to be stability indicating method.