The optimization of HPLC method involves several variables whose influence has been widely studied. However, in most of the cases, only process variables are taken into account. In this work, the influence of mixture composition on peak quality parameters of Pitavastatin calcium in bulk and tablet dosage form has been studied using a mixture simplex design. A simplex centroid design with axial points in a pseudocomponent representation was generated from the pure mixture components. Twelve ternary mixture mobile phases corresponding to augmented design points were tested to separate the drug in sample. The statistical analysis was performed to generate the polynomial equation for each response. The desirability approach was used to determine the optimal mobile phase composition. Further, the method was validated as per the ICH guidelines using specificity, linearity, accuracy, precision, sensitivity, system suitability and robustness. The results of experimental design were statistically tested for full and in portion to get best fitted model which accurately describe changes in the proportion of these solvents in the mobile phase close to the region of optimal peak quality. The method demonstrated optimum chromatographic separation with isocratic elution of the mobile phase containing a mixture of acetonitrile-water (pH 3.0)-tetrahydrofuran (43:55:02, v/v/v) with a flow rate at 1.0 ml/min. Design of experiment optimization strategy is a powerful tool to acquire the maximum quality data while performing minimum number of experiments. The mobile phase composition was successfully optimized using simplex centroid mixture design with desirability approach. Additionally, developed method can be applied for routine quantitative analysis of Pitavastatin calcium in bulk and tablet dosage form as it was found to be simple, sensitive and robust.
Key words: Pitavastatin calcium; RP-HPLC; Design of experiment; Mobile phase optimization; Simplex centroid design.
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