Chemometrical optimization FIA of perphenazine assay

A flow injection method for the assay of perphenazine using cerium(IV) as oxidant in a sulphuric acid media was adopted. Different chemometric techniques, considered the main objective of this work, were utilised to optimise sensitivity and sample throughput as a function of five experimental variables. The optimum conditions obtained by the super modified simplex method were, 0.170 M sulphuric acid, 2.13 mM cerium(IV), 2.56 ml min(-1) flow rate, 52 cm coil length, and 136 mul sample loop size. A central composite design was successfully employed, characterising the relation between these variables and the response surface, and hence validating the optimum conditions obtained by the simplex method. Regression analysis of the data from the experimental design, demonstration that a second order polynomial model is an adequate description of the surface over the factor limits studied. Further analysis of the response surface revealed the presence of a broad maximum around the simplex method optimum. A linear calibration curve in the range 50-500 ppm together with a sampling frequency of at least 120 s h(-1) and a relative standard deviation of less than 0.8% were obtained for the determination of perphenazine in its pure analytical grade. Results of the perphenazine assay in pharmaceutical preparations indicates that the method does not suffer interference from excipients rendering the method suitable for the assay of perphenazine in drug formulations.