The kinetics of the oxidation reaction of hydroxyzine hydrochloride with potassium hydrogen peroxomonosulfate was studied depending on the pH of the medium. It was established for the rst time that the kinetics of the reaction of N-oxidation of hydroxyzine obeyed the general laws of the mechanism of speci c acid-base catalysis, proceeded quantitatively and stoichiometrically according to the mechanism of nucleophilic substitution of the β-oxygen atom of the peroxyacid group of peroxomonosulfate ions. It was shown that quantitative oxidation was achieved in 1-1.5 minutes at pH 8.0-8.5. The only reaction product was hydroxyzine N-oxide. A scheme of the oxidation process was proposed. Techniques were developed and the possibility of quantitative determination of hydroxyzine hydrochloride in the substance and tablets of 25 mg by iodometry using Oxone as an analytical reagent was shown. A known excess of reagent was added, and after a predetermined time, the residual reagent was determined iodometrically. RSD ≤ 1.52%. (x̅ -µ)• 100 / µ < RSD. The procedures had several advantages such as speed, simplicity, accuracy, selectivity, and cost-effectiveness, and therefore could be easily adapted by quality control laboratories for routine analysis.
The kinetics of cystamine dihydrochloride oxidation by diperoxyadipic acid (DPAA) was studied in aqueous buffer solutions of pH 2.9, 6.9, 8.0, 8.5 and 9.2 under second-order conditions at the temperature 293 K. The second order rate constants, k (L mol−1 min−1) were calculated from kinetic values. A suitable mechanism scheme based on these observations was proposed. The possibility of application of DPAA as reagent for oxidimetric determination of cystamine dihydrochloride in tabtets was investigated. Cystamine dihydrochloride was determined by indirect titration with DPAA. The required amount of Cystamine dihydrochloride was dissolved in water, pH 8.0 buffer solution and DPAA solution was added. After 7 min, the solution was acidified. The excess DPAA was determined via iodometric titration. The advantages of the applied analytical techniques in the determination of cystamine dihydrochloride in tablets «Cystamine 0.2 g» was presented. The recovery of сystamine dihydrochloride was 99.32±1.45%. A paired t-test showed that all results obtained for bulk drug and in tablets «Cystamine 0.2 g», using the proposed procedure and the official procedure respectively, agreed at the 95% confidence level.
A new the oxidative derivatization method by means of peroxoacid for the indirect spectrophotometric determination of Periciazine is presented. A potassium hydrogenperoxymonosulfateas a derivatizing agent for Periciazine, yielding the absorbative Periciazine sulfoxide at λmaх=362 nm is proposed. This reaction product was successfully employed for spectrophotometric determination of the Periciazine. The UV spectrophotometric determination of the Periciazine as its sulfoxide proved to be the more simple and selective method. Limit of quantification (LOQ=10S) is 2.8 µg·mL-1. The common excipients employed do not interfere in the determination of phenothiazine drug. Results of analysis of the drug dosage forms by the proposed method are in good agreement with those of the official method. RSD=1.76 % (δ <RSD).
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