Spectrophotometric study was carried out, for the first time, to investigate the reaction between the vasodilator pentoxifylline hydrochloride (POX) and 1,2-naphthoquinone-4-sulphonate (NQS) reagent. The reaction occu...Spectrophotometric study was carried out, for the first time, to investigate the reaction between the vasodilator pentoxifylline hydrochloride (POX) and 1,2-naphthoquinone-4-sulphonate (NQS) reagent. The reaction occurs in alkaline medium to activate the nucleophilic substitution reaction producing an orange-colored product measured spectrophometrically at λ<sub>max</sub> 472 nm. The variables affecting the reaction were carefully studied and the conditions were optimized. The kinetics of the reaction was investigated and its activation energy was found to be 0.262 cal/mol. Owing to its low activation energy, the reaction proceeded easily and was successfully used for simple and rapid assay of POX. The stoichiometry of the reaction was determined (1:1), and the reaction mechanism was suggested. To develop a high-throughput methodology used in quality control laboratory, a comparative study of the reaction using the conventional spectrophotometric versus microwell assay was applied. Under the optimum reaction conditions, the initial rate and fixed time methods were utilized for constructing the calibration graphs for determination of POX concentrations. The linear range was 10 - 120 μg/ml with good correlation coefficients (0.9987 - 0.9998). The LOD was 2.5 and 3.4 μg/ml for initial rate and fixed time methods, respectively. The intra- and inter-day accuracy and precision of the developed methods were satisfactory, where RSD was ≤3.94%. The present methods have been successfully applied to the determination of POX in its pharmaceutical tablets, and the percentage recovery values were 97.9% - 101.9%. Therefore, we strongly recommend the proposed methods for determination of POX in quality control laboratories.展开更多
Simple and sensitive stability-indicating high performance thin layer chromatography (HPTLC) assay was developed and validated for quantitative determination of the antibacterial drug, gemifloxacin mesylate (GFX) in p...Simple and sensitive stability-indicating high performance thin layer chromatography (HPTLC) assay was developed and validated for quantitative determination of the antibacterial drug, gemifloxacin mesylate (GFX) in presence of its degradation products and ambroxol hydrochloride. The chromatographic separation was performed on HPTLC precoated silica gel plate 60F254 as stationary phase. The mobile phase consisted of a mixture of ethyl acetate: methanol: 25% ammonia, (8:4.5:3, v/v/v). The detection was performed using fluorescence mode and the emission intensity was measured using optical filter K400 after excitation at 342 nm. The Rf value for GFX was 0.47 ± 0.03. Good correlation coefficient was obtained over the concentration range of 1.5 - 180 ng/band. The LOD and LOQ of the proposed method were 0.28 and 0.86 ng/band, respectively. The proposed method was successfully applied for the analysis of GFX in its single and combined dosage forms. Moreover, it was utilized to investigate the kinetics of acidic, alkaline, neutral, oxidative and photolytic degradation of the drug. The apparent kinetic-order rate constants and half-life times of the degradation process were calculated. Furthermore, the proposed method was successfully applied for investigating the factors affecting the storage of GFX.展开更多
文摘Spectrophotometric study was carried out, for the first time, to investigate the reaction between the vasodilator pentoxifylline hydrochloride (POX) and 1,2-naphthoquinone-4-sulphonate (NQS) reagent. The reaction occurs in alkaline medium to activate the nucleophilic substitution reaction producing an orange-colored product measured spectrophometrically at λ<sub>max</sub> 472 nm. The variables affecting the reaction were carefully studied and the conditions were optimized. The kinetics of the reaction was investigated and its activation energy was found to be 0.262 cal/mol. Owing to its low activation energy, the reaction proceeded easily and was successfully used for simple and rapid assay of POX. The stoichiometry of the reaction was determined (1:1), and the reaction mechanism was suggested. To develop a high-throughput methodology used in quality control laboratory, a comparative study of the reaction using the conventional spectrophotometric versus microwell assay was applied. Under the optimum reaction conditions, the initial rate and fixed time methods were utilized for constructing the calibration graphs for determination of POX concentrations. The linear range was 10 - 120 μg/ml with good correlation coefficients (0.9987 - 0.9998). The LOD was 2.5 and 3.4 μg/ml for initial rate and fixed time methods, respectively. The intra- and inter-day accuracy and precision of the developed methods were satisfactory, where RSD was ≤3.94%. The present methods have been successfully applied to the determination of POX in its pharmaceutical tablets, and the percentage recovery values were 97.9% - 101.9%. Therefore, we strongly recommend the proposed methods for determination of POX in quality control laboratories.
文摘Simple and sensitive stability-indicating high performance thin layer chromatography (HPTLC) assay was developed and validated for quantitative determination of the antibacterial drug, gemifloxacin mesylate (GFX) in presence of its degradation products and ambroxol hydrochloride. The chromatographic separation was performed on HPTLC precoated silica gel plate 60F254 as stationary phase. The mobile phase consisted of a mixture of ethyl acetate: methanol: 25% ammonia, (8:4.5:3, v/v/v). The detection was performed using fluorescence mode and the emission intensity was measured using optical filter K400 after excitation at 342 nm. The Rf value for GFX was 0.47 ± 0.03. Good correlation coefficient was obtained over the concentration range of 1.5 - 180 ng/band. The LOD and LOQ of the proposed method were 0.28 and 0.86 ng/band, respectively. The proposed method was successfully applied for the analysis of GFX in its single and combined dosage forms. Moreover, it was utilized to investigate the kinetics of acidic, alkaline, neutral, oxidative and photolytic degradation of the drug. The apparent kinetic-order rate constants and half-life times of the degradation process were calculated. Furthermore, the proposed method was successfully applied for investigating the factors affecting the storage of GFX.
