A simple, sensitive, and stability indicating isocratic reverse phase high performance liquid chromatography method has been developed, optimized and validated for the separation and quantification of S-enantiomer in linagliptin (R-enantiomer) drug substance. Enantiomeric separation was achieved on a Cellulose tris(4-chloro-3-methylphenylcarbamate) stationary phase. Mobile phase consists of aqueous diammonium hydrogen phosphate buffer and acetonitrile in the ratio of 35:65 v/v. Isocratic elution was performed at a flow rate of 1.0 mL/min, the column oven temperature was set at 40°C and detection was at 226 nm. The resolution between R and S enantiomers is found to be more than 4.0. The impact of mobile phase composition, pH of buffer and temperature on the resolution has been studied. The detector response is found to be linear over the concentration range of 0.17-1.7 g/mL. LOD and LOQ levels of S-enantiomer are found to be 0.057 and 0.172 g/mL respectively. The recovery of S-enantiomer is 99.8% w/w. The proposed method is validated for specificity, precision, linearity, accuracy and robustness.

요 약. Isoxazole계 화합물을 합성하고 항균활성연구를 수행하였다. 3-Di(alkylamino)acryloalkanones을 hydroxylamine hydrochloride 또는 hydroxylamine-O-sulphonic acid와 반응시켜서 target isoxazole계 화합물을 합성하였다.주제어: Isoxazole계 화합물, 3-di(alkylamino)acryloalkanones, Hydroxylamine hydrochloride, Hydroxylamine-O-sulphonic acid, 항균활성 ABSTRACT. The synthesis, characterization and antibacterial activity of novel isoxazole derivatives were reported. 3-Di (alkylamino)acryloalkanones were prepared and used as synthons to get the target isoxazole derivatives via reaction with hydroxylamine hydrochloride or hydroxylamine-O-sulphonic acid.

A capillary gas chromatography method with a short run time, using a flame ionization detector, has been developed for the quantitative determination of trace level analysis of mesityl oxide and diacetone alcohol in the atazanavir sulfate drug substance. The chromatographic method was achieved on a fused silica capillary column coated with 5% diphenyl and 95% dimethyl polysiloxane stationary phase (Rtx-5, 30 m x 0.53 mm x 5.0 µm). The run time was 20 min employing programmed temperature with a split mode (1:5) and was validated for specificity, sensitivity, precision, linearity, and accuracy. The detection and quantitation limits obtained for mesityl oxide and diacetone alcohol were 5 µg/g and 10 µg/g, respectively, for both of the analytes. The method was found to be linear in the range between 10 µg/g and 150 µg/g with a correlation coefficient greater than 0.999, and the average recoveries obtained in atazanavir sulfate were between 102.0% and 103.7%, respectively, for mesityl oxide and diacetone alcohol. The developed method was found to be robust and rugged. The detailed experimental results are discussed in this research paper.

A simple and sensitive reverse phase ultra performance liquid chromatography (RP-UPLC) method has been developed, optimized and validated for the simultaneous determination of N-Hydroxybenzotriazole (HOBt), Cinchonidine and 1,3-Dicyclohexyl urea (DCU) contents at low levels in fosinopril sodium drug substance. Efficient chromatographic separation was achieved on Acquity UPLC HSS C18column, 100 mm long with 2.1 mm i.d., 1.8 µm particle diameter, thermo stated at 30°C. Gradient elution involving binary mixture of potassium dihydrogen orthophosphate (0.01M, pH:3.0±0.05 withortho-phosphoric acid) and acetonitrile at a flow rate of 0.10 mL min-1has been used. The analytes were monitored by photodiode array (PDA) detector set at 205 nm. The drug substance was subjected to stress conditions of hydrolysis, oxidation, photolysis, thermal and humidity degradation. The method was validated for specificity, sensitivity, linearity, precision, accuracy and solution stability. The limit of detection (LOD) and limit of quantification (LOQ) for HOBt, Cinchonidine and DCU were in the range of 0.85-3.52 ppm and 2.57-10.67 ppm, respectively. The average recoveries for HOBt, Cinchonidine and DCU are in the range of 98.1% to 102.6%. The method can be used for the routine quality control analysis of fosinopril sodium drug substance.

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