Efficient electrochemical sensing of methyl parathion residues using a PEDOT:PSS/Zr(OH)4/ZIF-90 composite

Abstract

To achieve the rapid and sensitive detection of trace methyl parathion (MP) in river water and edible agricultural products, the catalytic composite material zirconium hydroxide (Zr(OH)₄)/zeolite imidazolate framework-90 (ZIF-90) was prepared by a one-step synthesis method. The composite was further incorporated with a conductive poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hydrogel to prepare a modified electrode. Then, an electrochemical sensing method based on the PEDOT:PSS/Zr(OH)₄/ZIF-90 composite was successfully established for the analysis and detection of MP. The component ratio of the composite material, modification amount and pH value of the detection substrate were optimized. The electrochemical properties of the composite modified electrode were evaluated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques, and the results confirmed that it had good electrochemical properties. The electrochemical response of the established sensing method to MP showed a good linear relationship in the concentration range of 1–250 µmol L⁻¹, and its detection limit and sensitivity reached 0.74 µmol L⁻¹ and 0.09 µA µmol⁻¹ L⁻¹, respectively. The interference of common coexisting ions on the detection performance of the PEDOT:PSS/Zr(OH)₄/ZIF-90 modified electrode was further investigated, and it was applied for the quantitative analysis of MP in actual river water and apple samples. The electrochemical sensing method developed in this work provides a new way for the efficient detection of MP residues in environmental water and agricultural products.