Background: Optimization of mobile phase for high performance liquid chromatography (HPLC) is an exigent task where one factor at a time (OFAT) approach is not preferable as it is time consuming specially for multifaceted samples. The paper describes Augmented Simplex Centroid Design (ASCD) for optimization of ternary mobile phase system for reversed phase HPLC method. The proposed design was utilized for development of mobile phase composition for simultaneous estimation of curcumin and piperine present in dietary supplement. Materials and Methods: Separation was achieved on Sunniest C 18 column (150 mm x 4.6 mm, 5µ). Elution was carried out using in isocratic mode using mobile phase, 0.1 % OPA: ACN: THF (52.7: 37.3: 10.0, v/v/v) at flow rate of 1 ml/min. Sample injection volume was 20 µl. Detection was carried out at 361 nm and run time was 20 min. Results: The proposed method was linear over concentration range of 1 -6 µg/ml for both curcumin and piperine with the regression coefficient 0.9954 and 0.9575, respectively. The limit of detection of the proposed HPLC method for curcumin and piperine were found to be 0.0621 µg/ml and 0.0633 µg/ml, respectively. The limit of quantification of the proposed HPLC method for curcumin and piperine were found to be 0.1863 µg/ml and 0.1899 µg/ml, respectively. The percentage recovery of both curcumin and piperine were found to be in the range of 96.5366 -115.6833 %. The proposed method was precise and robust. Conclusion: The method was successfully applied for standardization of dietary supplement containing curcumin and piperine.

Captopril was quantitatively determined by colorimetry using ferric chloride and potassium ferricyanide. 33 factorial design with help of design expert software (version 9.0.4) was used for optimisation of method. Effect of method variables such as concentration of ferric chloride, concentration of potassium ferricyanide and volume of both reagents was evaluated on method response absorbance. Optimum concentration of ferric chloride and potassium ferricyanide was found to be 0.3% and 0.2%, respectively and optimum volume of both reagents was found to be 1.5 mL. The developed method was validated as per ICH guidelines. The linearity of the proposed method was found in the concentration range of 1.0 – 6.0 μg/mL with regression coefficient (R2) of 0.9913. The % recovery was found between 98.23- 104.25 %. The method was found to be precise as the values of % RSD obtained were found to be