3 FACTORIAL DESIGN FOR OPTIMISATION OF COLORIMETRIC METHOD FOR QUANTIFICATION OF CAPTOPRIL

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