Spectrophotometric determination of perphenazine with the detection system of potassium ferricyanide–Fe(III) in pharmaceutical and serum samples

In this paper, a novel spectrophotometric method has been established to determine perphenazine using the detection system of potassium ferricyanide–Fe(III). In the presence of potassium ferricyanide, it has been demonstrated that Fe(III) is reduced to Fe(II) by perphenazine at pH 4.0. In addition, soluble prussian blue (KFeIII[FeII(CN)6]) is produced by the reaction between the in situ formed Fe(II) and potassium ferricyanide. The absorbance of soluble prussian blue is measured at the absorption maximum of 735 nm, and the amount of perphenazine can be calculated based on this absorbance. The absorbance is linear to perphenazine concentration in the ranges of 0.05–25.00 μg/mL with correlation coefficients of 0.9997, and the linear regression equation is A = 0.0069 + 0.1285C (μg/mL). The detection limit (3σ/k) is 0.049 μg/mL, and the relative standard deviation (R.S.D.) is 0.86% (n = 11). Moreover, the apparent molar absorption coefficient of indirect determination of perphenazine is 5.2 × 104 L/mol cm. The parameters with regard to determination are optimized, and the reaction mechanism is discussed. This method has been successfully applied to the determination of perphenazine in pharmaceutical and serum samples. Analytical results obtained with this novel assay are satisfactory.