L-ARGININE DETERMINATION IN BIOLOGICALLY ACTIVE ADDITIVE BY VOLTAMMETRY

Abstract

This article reports about the electrochemical determination of L-arginine on a glassy carbon electrode in a dietary supplement using anodic differential pulse voltammetry. The exponential depense of the peak current on the square root of the scan rate (I/v1/2), the shifts of the potential to the negative area and linear correlation between peak potential and logarithm of the scan rate (lg(v)) confirms that electrooxidation of L-arginine is an irreversible process. Moreover, the criteria of Semerano equals 0.4 may indicate the process of electrooxidation without adsorption. The effect of pH, accumulation potential, accumulation time and scan rate was tested on electrochemical behavior of L-arginine. Working conditions for L-arginine determination in model media are following: pH 13; Eacc 0.3 V, tacc 30 s; v = 60 mV s-1. A linear dependence of L-arginine electrooxidation current on its concentration was observed at the 0.9 V in the range between 1.0∙10-4 and 10∙10-4 mol l-1. The detection limit was 1.34∙10-6 mol l-1. A comparative determination of L-arginine in dietary supplement was carried out by the voltammetric method and capillary electrophoresis. Thus, the determination of L-arginine in a dietary supplement on a glassy carbon electrode in NaOH solution (pH 13) was successfully carried out using anodic differential pulse voltammetry. The proposed method does not require sample preparation and allows to quickly determine L-arginine in dietary supplement.