Determinação Voltamétrica do Antioxidante Galato de Propila em Biodiesel Empregando Eletrodos de Pasta de Carbono Modificados com Líquido Iônico

Abstract

In this work a carbon paste electrode chemically modified with an ionic liquid (CPE-IL) was used to quantify the antioxidant propyl gallate (PG) in spiked soybean biodiesel samples by square wave voltammetry. Under the optimized conditions, the proposed method have presented a linear range from 2.0 to 47.5 μmol L-1, with limit of detection equal to 0.397 μmol L-1. Recovery studies were performed in biodiesel samples spiked with two levels of PG. In all cases, satisfactory recovery percentages and low relative standard deviation values were obtained which is a clear demonstration of the accuracy of the proposed method. It was observed that IL provides a remarkable intensification of PG voltammetric response compared to a non-modified conventional CPE, improving, therefore, the detectability of the voltammetric method. The CPE-IL used in this work does not require an IL completely free from residual water. This is a very attractive feature because time-consuming procedures for water elimination are avoided during the synthesis of the IL. Thus, the proposed CPE-IL can be prepared in a simple, fast and inexpensive way making these electrodes very practical and competitive compared to other chemically modified electrodes proposed in the literature for PG quantification.

Keywords

• biodiesel
• carbon paste electrodes
• square wave voltammetry
• propyl gallate
• electroanalysis