Bimetallic Mn/Fe MOF modified screen-printed electrodes for non-enzymatic electrochemical sensing of organophosphate

This study presents a novel strategy to fabricate an electrochemical sensor based on a screen-printed electrode (SPE) modified by a bimetallic Mn2+/Fe3+ metal-organic framework (MnFe-MOF) for the direct determination of organophosphate pesticide chlorpyrifos. Square wave voltammetry technique was employed for the electroanalysis, and the limit of detection remained as low as 0.85 nM or 0.29 ppb in a wide linearity range of 1.0 × 10-9 to 1.0 × 10-7 M. The sensor also demonstrated exceptional repeatability and anti-interference performance. Moreover, MnFe-MOF was synthesized using terephthalic acid as the building block using a one-pot solvothermal approach. Multiple characterization studies confirmed the formation of the MOF. The bimetallic MnFe-MOF exhibited high adsorption and electrocatalytic properties towards chlorpyrifos due to the hetero-metal synergism arising between the Mn2+ and Fe3+ ions, owing to which it was employed as the electrode material for non-enzymatic electro-determination of chlorpyrifos. The proposed sensor displayed a satisfactory recovery of the spiked pesticide in real-sample matrices.