Sensitive determination of paraquat by square wave anodic stripping voltammetry with chitin modified carbon paste electrode

A novel analytical approach has been developed and evaluated for the quantitative analysis of paraquat herbicides which can be found at trace levels in olive oil and olives. The aim of this work is to optimize all factors that can influence this determination by a carbon paste electrode modified with chitin (Chit-CPE). The best responses were obtained with square wave potential in diluted Na2SO4 as supporting electrolyte. The influence of various parameters on the Chit-CPE was investigated. Under the optimized working conditions, calibration graphs were linear in the concentration ranges of 5.0×10−9-1.0×0−5 mol L−1. For 180 s preconcentration, detection limits of 2.67×10−10 mol L−1 (peak 2) was obtained at the signal noise ratio (SNR) of 3. To evaluate the reproducibility of the newly developed electrode, the measurements of 1.0×10−5 mol L−1 PQ were carried out for seven times at Chit-CPE and the relative standard deviation was 5.2%. The analytical methodology was successfully applied to monitor the paraquat content in olives and olive oil.