Recently, dynamic approach has been applied to determine the steady state concentrations of multiple ionic species present in complex buffers at equilibrium. Here, we have used the dynamic approach to explicitly model the pH profiles of biologically relevant phosphate buffer and universal buffer (a mixture of three tri-protic acids such as citric acid, boric acid and phosphoric acid). The results from dynamic approach are identical to that of the conventional algebraic approach, but with an added advantage that the dynamic approach, allow for the modelling of complex buffer systems relatively easy compared to that of algebraic method.

An unknown impurity formed during stability sample analysis by a gradient reversed phase ultra-high pressure liquid chromatography (UHPLC) of varenicline tablets at 0.2% level. A simple isocratic preparative method was developed to isolate the unknown impurity with 20 min run time. This unknown impurity was identified and characterized by using spectroscopic techniques. Based on the spectral data, the unknown impurity has been characterized as 4,6,7,8,9,10-hexahydro-1H-6,10-methanopyrazino[2,3-h][3]benzazepine-2,3-dione. The structure of this impurity was also established unambiguously, prepared by isolation and co-injected into UHPLC to confirm the retention time. To the best of our knowledge, this impurity has not been reported elsewhere.

ABSTRACT:A simple, rapid and precise spectrophotometric method has been developed for simultaneous estimation of Metformin and Glipizide. The method involved estimation of Metformin and Glipizide by simultaneous equation at 272nm and 232nm respectively in their solution in water. This method was validated with respect to linearity, accuracy, precision, LOD and LOQ. Beer's law obeyed in the concentration range of 5-25µg/ml and 20-50µg/ml for Metformin and Glipizide respectively with the correlation coefficient of above 0.99. Limit of detection and quantification values were determined to be 0.214μg/ml and 0.649μg/ml for Metformin and 0.608μg/ml and 1.854μg/ml for Glipizide respectively. Mean recovery of Metformin and Glipizide were found to be in the range of 98-102% signifies the accuracy of the method. The method was found to be precise as %RSD was less than 2.

No abstract

No abstract