ABSTRACT
A selective high-performance liquid chromatographic procedure for the stability-indicating determination of danazol in the presence of its photolytic degradation products is demonstrated. The photolysis was carried out in glass vials and quartz cell under UV light at 254 nm. Satisfactory results were obtained for the assay and recovery testing with RSD values less than 2%. Kinetic parameters evaluated comprise the order of reaction and the rate constants of the degradation of the danazol irradiated in glass vials or quartz cell.
Subject(s)
Chromatography, High Pressure Liquid/methods , Danazol/analysis , Kinetics , Photochemistry , Ultraviolet RaysABSTRACT
A highly sensitive and simple voltammetric method is proposed for the determination of N-nitrosoatenolol (NA) and N-nitrosopropranolol (NP) in simulated gastric juice. The method is based on measuring the differential-pulse polarographic peak produced by NA and NP in Britton-Robinson buffers of pH 3 and 4 for NA and NP, respectively. Both compounds yielded diffusion-controlled current with diffusion-current constants of 7.23 +/- 0.03 and 9.46 +/- 0.06 for NA and NP, respectively. The current-concentration plots were rectilinear over the range 0.16-9.6 micrograms ml-1 with minimum detectability (S/N = 2) of 0.015 microgram ml-1 (5 x 10(-8) M) for NA; for NP the range was 0.08-8.0 micrograms ml-1 with minimum detectability (S/N = 2) of 0.009 microgram ml-1 (3 x 10(-8) M). The proposed method was successfully applied to study the possible in vivo production of the nitroso-derivatives under the standard nitrosation reaction conditions recommended by WHO. The method is characterized by simplicity and higher sensitivity as compared with the reported HPLC method.
Subject(s)
Atenolol/metabolism , Nitrosamines/analysis , Propranolol/analogs & derivatives , Chromatography, High Pressure Liquid , Hydrogen-Ion Concentration , Nitrosamines/metabolism , Polarography , Propranolol/analysisABSTRACT
High performance liquid chromatographic methods for the individual determination of khellin, phenobarbitone and dipyrone in tablets are presented. The methods specify a reverse phase column: methanol + water (68 + 32) as mobile phase at a flow rate of 0.7 ml/min with detection at 254 nm for khellin, visgnagin and dipyrone; water + ammonia + methanol (94.5 + 0.5 + 5) as a mobile phase at a flow rate of 0.7 ml/min with detection at 240 nm for phenobarbitone. At sensitivity of 0.01 AUFS, linearity ranges were found to be 0.5-4 micrograms/ml for khellin, 2.5-12.5 micrograms/ml for dipyrone and 1-7 micrograms/ml for phenobarbitone and with relative standard deviations less than 2%. The mean percentage recoveries +/- SD of khellin, dipyrone and phenobarbitone added to tablets were found to be 101.0 +/- 0.65, 100.0 +/- 0.74 and 99.9 +/- 0.74, respectively. The system can detect 2% w/w visnagin in khellin.
Subject(s)
Aminopyrine/analogs & derivatives , Dipyrone/analysis , Khellin/analysis , Phenobarbital/analysis , Chromatography, High Pressure Liquid , Drug Combinations , Indicators and Reagents , Spectrophotometry, Ultraviolet , TabletsABSTRACT
Piperazine and its salts are reacted with aqueous alcoholic p-benzoquinone, buffered at pH 5.4, to give a coloured product with maximum absorption at 516nm. The piperazine base has a molar absorptivity of 0.96 x 10(4)l.mole(-1).cm(-1) and Beer's law is obeyed over the range 2-10 mug ml . When applied to three commercial preparations, the proposed method gave mean recoveries within 1% of those obtained by the official gravimetric method. The relative standard deviation was less than 1%.
