ABSTRACT
The chromogenic reagent p-dimethylaminocinnamaldehyde (PDAC) is introduced for the determination of the sympathomimetic amines methyldopa and noradrenaline. The method is based on measurement of the orange color developed when the alkaline solution of methyldopa and noradrenaline is allowed to react with PDAC at pH 5.0. The color developed obeys Beer's law in the concentration range 0.1-1.5 mL of 2 X 10(-3)M solution of noradrenaline and methyldopa. The results are compared with those obtained with another chromogenic reagent, p-dimethylaminobenzaldehyde (PDAB). Determinations on dosage forms of the drugs, using PDAC and PDAB reagents, agreed well with results of determinations by official pharmacopoeial methods.
Subject(s)
Methyldopa/analysis , Norepinephrine/analysis , Benzaldehydes , Chemical Phenomena , Chemistry , Cinnamates , Colorimetry/methods , Hydrogen-Ion Concentration , Indicators and Reagents , Solutions/analysis , Tablets/analysis , TemperatureABSTRACT
A variety of substituted amides of 6,7-dimethoxy-2-hydroxyquinoline-3-carboxylic acid were synthesized. Three of these compounds, tested as potential central nervous system stimulants, showed no marked biological activity.
Subject(s)
Central Nervous System Stimulants/chemical synthesis , Quinolines/chemical synthesis , Animals , Behavior, Animal/drug effects , Chemical Phenomena , Chemistry , Mice , Monoamine Oxidase Inhibitors/chemical synthesis , Quinolines/pharmacologyABSTRACT
The direct current polarographic behaviour of the bromometric oxidation product of certain penicillins has been investigated. The oxidized products give a well defined cathodic wave with E1/2 = 0.6 V vs saturated calomel electrode (SCE). The nature of the wave and the electrode reaction have been evaluated. A procedure was developed for investigation of the penicillins either in the pure state or in dosage forms. The results were compared with those obtained with the official methods.
Subject(s)
Penicillins/analysis , Ampicillin/analysis , Bromates , Bromides , Capsules/analysis , Diffusion , Electrochemistry , Oxidation-Reduction , Polarography , Tablets/analysis , TemperatureSubject(s)
Phenothiazines/analysis , Indicators and Reagents , Solutions/analysis , Tablets/analysisABSTRACT
New oxidimetric titrants, bromamine T, dibromohydantoin, N-bromophthalimide, and N-bromosuccinimide, were applied to the determination of ephedrine.HCl, norephedrine.HCl, and methyldopa. Direct potentiometric and visual indicator titration methods as well as back-titration procedures have been developed for their determination. Oxidation of ephedrine and norephedrine produces benzaldehyde, which is extracted from pH 11.0 phosphate buffer with ether or hexane and determined spectrophotometrically at 242 nm. Beer's law is obeyed in the concentration range from 0.2 to 2 mg ephedrine.HCl and from 0.15 to 1.9 mg norephedrine.HCl. Methyldopa is determined titrimetrically and spectrophotometrically. In addition, this drug acts as a self-indicator: Solutions change from colorless to red, which gradually disappears with continuous addition of brominating agent and shaking. Phosphate buffer is used to produce adrenochrome, characterized by its pink color which can be measured at 485 nm in a working range from 40 to 650 micrograms.
Subject(s)
Bromine , Ephedrine/analysis , Methyldopa/analysis , Phenylpropanolamine/analysis , Indicator Dilution Techniques , Solutions/analysis , Spectrophotometry , Tablets/analysisABSTRACT
Simple colorimetric methods are reported for determining both acetaminophen and oxyphenbutazone. These methods are based on coupling between the phenolic compound and the diazonium salts of both sulfanilic acid and p-nitroaniline; the optimum conditions for the reactions were carefully studied. For acetaminophen, the reaction products with diazosulfanilic acid and diazo-p-nitroaniline show maximum absorbance at 480 and 425 nm, respectively. The mean percentage recoveries for authentic samples were 99.5 +/- 1.1 and 100.6 +/- 0.66, respectively (P = 0.05). For oxyphenbutazone, the obtained colors showed maxima at 385 nm with diazosulfanilic acid and 490 nm with diazo-p-nitroaniline reactions. The mean percentage recoveries for authentic samples were 99.8 +/- 0.27 and 100.1 +/- 0.57, respectively (P = 0.05). The proposed methods were successfully applied to the analysis of commercial preparations; results were statistically compared with those of other methods.
Subject(s)
Pharmaceutical Preparations/analysis , Phenols/analysis , Acetaminophen/analysis , Colorimetry/methods , Dosage Forms , Indicators and Reagents , Oxyphenbutazone/analysisABSTRACT
A spectrophotometric determination of piperazine and some of its salts is described. The method depends on the UV measurement of the N-nitroso derivatives formed by the interaction of piperazine with nitrous acid. The chromophore is developed by heating the reaction mixture at 80 degrees C for 15 min, at pH 2.3--2.6. Beer's law is obeyed in the range 1--15 micrograms/mL.
