Initially, the electrochemical behavior of paraquat was evaluated using the voltammetric results at carbon paste electrode modified with chitin. The voltammetric response showed two oxidation waves associated to the partial oxidation of paraquat molecule. The influence of the experimental variables which were involved in the SWASV determination of paraquat was investigated. The results indicate that the method developed for the analytical determination of paraquat using chitin modified paste electrode is applicable for the determination of the pesticide at 2.67×10−10 mol L−1 levels with very good precision. The use of SWASV is faster and more sensitive than other conventional techniques in confidence interval of 95%.
The analytical utility of this procedure was assessed by applying it to the determination of paraquat in olives and oils samples containing this herbicide. The slight decrease in the values of the recovery of obtained paraquat reflects an electrochemical process involving adsorption of reagents and/or products. This can be inhibited by the presence of other components in the samples used.
In this way, the use of carbon paste electrode in conjunction with SWASV in determining paraquat proves to be a very suitable and efficient analytical methodology which permits its application in a variety of different natural matrices.