Electrochemical Determination of Paraquat Using Ordered Mesoporous Carbon (CMK-3) Modified Glassy Carbon Electrode

Abstract

Ordered mesoporous carbon namely, CMK-3 was synthesized by nano casting method, and characterized using various physicochemical and electroanalytical tools like HESEM, HRTEM, BET, etc. Using Cyclic voltammetric (CV) measurements on CMK-3 modified glassy carbon electrode (CMK-3/GCE) in the standard redox couple, [Fe(CN)6]3−/4−, the electrochemical surface area was deduced as 0.081 cm2. The modified electrode was used as an electrocatalyst for the determination of one of the herbicides, paraquat (PQ). The modified electrode shows enhanced sensitivity for the determination of PQ in phosphate buffer solution at pH 9.2 as compared to bare GCE. The concentration dependant CV studies showed a linear variation in sensitivity in the concentration range of 60 μM to 450 μM. The effect of the scan rate shows a linear variation in sensitivity as a function of the square root of scan rate suggesting a diffusion-controlled process during the detection of PQ. Anodic stripping square wave voltammetry (ASSWV) reveals the sensitivity and limit of detection as 9.51 μA μM−1 and 64 nM, respectively. The interfering ability of the other foreign molecules like metal ions, environmental samples, biomolecules, and pesticides was analyzed using CMK-3/GCE. The results revealed that the electrode is able to sense paraquat, with the retention in sensitivity ranges between 91% and 102%. The real-time applicability of the electrode was examined using vegetable and fruit extracts. The analysis revealed that the recovery values were between 102 % – 105 %.