Eletrodo modificado com filme de poli aminoácido para determinação de hidrazina em água de caldeira

Abstract

Glassy carbon electrodes were modified by films of poly glutamic acid (PAG) obtained after electropolymerization of the glutamic acid in pH 7.0 phosphate buffer solution under successive voltammetric scans from -0.8 V to +2.0 V. The modified electrode were applied for determination of hydrazine, which is preconcentrated on the electrode surface by interaction of free carboxylic groups bearing in the PAG film and amino group of hydrazine. Although, hydrazine is not electrochemically oxidized on bare electrode, a well defined peak is observed at + 0.57 V with great analytical potentiality. Linear calibration graphs were obtained for hydrazine at concentrations from 4 × 10 -5 to 1 × 10-3 mol L-1, using differential pulse voltammetry. Detection limit was calculated and values around 1.2 × 10-6 mol L-1 were obtained. The proposed method was applied to the determination of hydrazine in samples collected from industrial kettle with recovery of around 94%.