An amino-modified metal-organic framework (type UiO-66-NH 2 ) loaded with cadmium(II) and lead(II) ions for simultaneous electrochemical immunosensing of triazophos and thiacloprid

A method is described for simultaneous voltammetric determination of the pesticides triazophos (TRS) and thiacloprid (THD). A glassy carbon electrode (GCE) was modified with a metal-organic framework (type UiO-66-NH2) which has a large specific surface (1018 m2·g−1) and contains large amounts of Cd(II) and Pb(II) ions, with adsorption capacities of 230 and 271 mg·g−1, respectively. The antigen-loaded particles were then bound to antibody, magnetically separated, and analyzed by square wave voltammetry to give signals for Cd(II) and Pb(II) at −0.82 and − 0.56 V (vs. Ag/AgCl) for TRS and THD, respectively. Under optimized conditions, the method has a wide linear range (0.2–750 ng·mL−1) and low detection limits (0.07 and 0.1 ng·mL−1 at a S/N of 3 for TRS and THD, respectively). It is perceived that this assay represents a useful tool for simultaneous determination of multiple pesticide residues. The method has a wide scope in that may be extended to monitoring of other small organic pollutants by changing the types of metal ions and by using other antibodies.