Sensitive and validated voltammetric methods for determination of zileuton in serum, urine and pharmaceutical dosage forms at activated glassy carbon electrode

Abstract

A simple, precise and sensitive voltammetric methods determination of zileuton were presented at activated glassy carbon electrode in Britton-Robinson buffer of pH 8 by differential pulse voltammetry and square wave voltammetry methods. A study of the variation of the peak current with solution variables such as pH, ionic strength, concentration of drug, possible interference and instrumental variables such as scan rate, pulse amplitude, accumulation potential, has resulted in the optimization of the reduction signal for analytical purposes. Linear calibration plots were obtained over the concentration ranges of 2.0 × 10-6 to 1.2 × 10-5 and 1.0 × 10-6 to 1.8 × 10-5 mol/L, respectively, using differential pulse voltammetry and square wave voltammetry methods. The correlation coefficients were 0.9977 and 0.9947 for differential pulse voltammetry and square wave voltammetry methods, respectively. The linear response was obtained in Britton-Robinson buffer in the range of 2.0 × 10-6 – 2.0 × 10-5 and 2.0 × 10-6 – 3.1 × 10-5 mol/L for spiked serum and urine samples, respectively. The limit of detection (LOD) and limit of quantification (LOQ) were 1.3 × 10-9 and 3.95 × 10-9 mol/L for differential pulse voltammetry method and 2.34 × 10-10 and 6.99 × 10-10 mol/L for square wave voltammetry method. The RSD for five measurements were 0.0489 and 0.0885 using 50 mV/s scan rate. The methods were applied for the determination of zileuton drug in dilute serum, urine samples and pharmaceutical dosage form with satisfactory results and compared with the official reference method. Complete validation of the proposed method was also done.