A disposable and inexpensive bismuth film minisensor for a voltammetric determination of diquat and paraquat pesticides in natural water samples

The development of a bismuth film on a disposable minisensor for electroanalytical determination of Diquat (DQ) and Paraquat (PQ) using voltammetric techniques as square-wave (SWV) and differential-pulse (DPV) is reported. The disposable minisensor consisted of a bismuth film-working electrode, a silver-pseudo-reference and copper-counter electrodes. Copper boards of a printed circuit were used as substrate and nail varnish was used as an electrical insulator to limit the electrode area. The disposable proposed minisensor was applied for the determination of DQ using SWV and PQ using DPV. Under optimal experimental conditions, the cathodic peak current was linear in the DQ concentration range of 0.19 × 10−6-9.3 × 10−6 mol L−1 with a detection limit of 8.9 × 10−8 mol L−1, and, for PQ the peak current was linear in the concentration range of 0.12 × 10−6-4.2 × 10−6 mol L−1 with a detection limit of 1.2 × 10−8 mol L−1. The proposed method was applied for the determination of both pesticides in natural water samples and the obtained results are in good agreement with those results obtained using a high-performance liquid chromatography at a 95% confidence level.