Stability indicating method for the determination of clonazepam and nordiazepam each in presence of its degradation product

The present work describes a quantitative thin layer procedure for estimating clonazepam and nordiazepam in bulk powder and in dosage forms each in presence of its degradation product. The method consists of dissolving the drugs in methanol and then spoting this solution on a thin layer of silica gel G245. Quantitation is achieved by comparing the areas under the peaks obtained from scaning the thin layer chromatographic plates in a spectrodensitometer

Spectrophotometric determination of pantoprazole sodium in presence of its degradation products

Four spectrophotometric procedures [A-D] for the determination of pantoprazole sodium were investigated. Procedures A and B are stability-indicating methods to determine the intact drug in presence of its degradation products; sulfenamide and sulfenic acid prepared by degrading the pure drug in borate buffer [pH 8] at 37C for 5 days. Procedure A is based on first derivative spectrophotometric measurement in ethanol at 305 nm, whilst procedure B involves coupling of the drug with 2,6-dichloroquinone chlorimide in ethanoldimethylformamide mixture to yield a purple coloured product picked at 515 nm. Procedures C and D depend on charge transfer complexation with dichlorophenol indophenol and dichloronaphthoquinone in CHCl3-methanol and dimethylformamide yielding blue and orange radical anions with lambda max at 640 and 495 nm, respectively. Regression analysis of Beer's plots show good correlations [r=0.9992- 0.9999] and the calibration curves are linear over the ranges of 5-20 mug ml-1, 30-240 mug ml-1, 2-16 mug ml-1 and 40-320 mug ml-1 for procedures A,B,C and D, respectively. The detection limits range between 0.14 and 4.16 mug ml-1. Procedures A and B retain their accuracies in presence of up to 60% and 30% of pantoprazole degradation products, respectively. The average recoveries for commercial tablets are 98.9-100.4%. The results proved to be reproducible and in accordance with those given by a compendial method[11]