Amperometric sensors based on sawdust film modified electrodes: Application to the electroanalysis of paraquat

Natural or sodium hydroxide treated Ayous sawdusts were used to prepare thin film electrodes (denoted respectively as PSTFE and SSTFE). The sensors obtained exhibit good mechanical stability and a wide electrochemical potential range. Their electrochemical characterization revealed that they present a good capacity to accumulate cations, but are not useful for the electroanalysis of anions. In all cases, the signals were more intense and well defined on SSTFE compared to PSTFE. When applied to the electroanalysis of paraquat, a significant improvement of the current intensities was obtained on these electrodes compared to the bare glassy carbon electrode. The diffusion of this compound through the film which is the main process governing the electrochemical reaction at the electrode surface, is 2.2 times more important with SSTFE compared to PSTFE. After the optimization of the detection parameters, calibration curves were obtained in the concentration range 0.1–0.725 μmol L−1 for PSTFE and 0.05–0.6 μmol L−1 for SSTFE. The detection limits determined for a signal/noise ratio=3 are 5.49×10−9 mol L−1 for PSTFE and 3.02×10−9 mol L−1 for SSTFE.