ABSTRACT A novel, accurate, precise and economical stability indicating Reverse Phase-High Performance Liquid Chromatography (RP-HPLC) method, was developed and validated for the quantitative determination of ubidecarenone (UDC) in bulk drug, UDC marketed formulation and UDC loaded cubosomes (CBMs) nanocarriers through Response surface methodology (RSM) design with three factors and three levels was performed to optimize the chromatographic variables followed by forced degradation studies of UDC were performed to detect degradation peak. RP-HPLC separation was achieved using mobile phase consisting of Acetonitrile:Tetrahydrofuran:Deionised water in the ratio 55:42:3 and a flow rate of 1.0 mL/min was optimized with a standard retention time (Rt) of 2.15 min, through experiment. The method was found linear in the concentration range of 5-100 µg/mL with a regression coefficient of 0.999. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 3.04 µg/mL and 9.11 µg/mL, respectively.

Pravastatin, a natural bioactive compound inhibits cholesterol biosynthesis which is isolated from fungus by fermentation process. A rapid, sensitive and robust novel reversed phase-HPLC method with UV detection set at 238 nm was developed and validated for quantification of pravastatin in pure drug form and pharmaceutical formulation (Pravachol). A liquid-liquid extraction technique was applied for the preparation samples and chromatographic separation was performed on Symmetry® C (5pm, 3.9 x 150 mm) column with a retention time of 1.95 min using isocratic elution of mobile phase. The mobile phase used in this work consisted of a mixture of methanol and phosphate buffer (70:30%, v/v, pH 4) which was delivered at a flow rate at 1.5 ml/min. Developed HPLC-UV method was validated for linearity (R² = 0.999), accuracy, precision, sensitivity, system suitability, selectivity, and robustness. Box-Behnken experimental design was applied in the validation of robustness. Three independent variables such as the composition of mobile phase, flow rate and pH of mobile phase were investigated. The results indicated that a slight change in the mobile phase composition and flow rate affects the responses, while pH had no significant effect on the response. Overall, the proposed HPLC-UV method was found to be simple, sensitive, and highly robust for routine analysis of pravastatin.

A simple, highly sensitive, isocratic stability indicating reversed phase-high performance liquid chromatography (RP-HPLC) method with UV detection at 247 nm was developed and validated for analysis of atorvastatin (AT). Retention time of the AT was found to be 4.02 min. A mobile phase consisting of 0.05 M sodium phosphate buffer and methanol (3:7 v/v) pH 4.1 at flow rate of lµL/min was employed in this study. The calibration curves were linear with regression coefficient (r²) of 0.9997 ± 0.0014. The limits of detection (LOD) and the limits of quantification (LOQ) were found to be 0.20 and 0.60 µg/mL, respectively. The method was statistically validated in accordance with International conference on harmonization (ICH) guidelines. The proposed method was found sensitive, specific and was successfully applied for the estimation of atorvastatin in pharmaceutical formulations (bulk drug, tablet, nanoemulsion).

The stability constants of the mixed ligand ternary complexes of nickel(II) of the type MAB, MA2B and MAB2 (where A = histidine, B = diols, viz. ethane diol, propane- 1,2-diol, butan-l,3-diol, 2-butene-1,4-diol, pentane-2,4-diol and hexane-1,6-diol) were determined by potentiometric method. The difference in the stability constants of binary and ternary complexes (AlogK) and total enhancement of stability due to mixed ligand complex formation (log X) were of greater magnitude in MA2B systems than those in MAB2 systems. This appeared to be due to the greater number of nitrogen atoms coordinating to metal ion in the MA2B species. Some changes in the stability constants nave been found to be due to the variation in the size of the ring formedby diols. The stability of 2-Butene-1,4-diol containing species exhibited the highest stability in this series. It was concluded that the íi-system of the ligands is important for such a great increase in stability.