Determination of methyl parathion and fenitrothion on a Mg-Al layered double hydroxide/poly-m-amino-benzenesulfonic acid film-coated glassy carbon electrode (Mg-Al LDH/p-m-ABSA/GCE)

A novel nonenzymatic electrochemical sensor with high sensitivity for detecting organic phosphate (OPS) in medicinal herbs was fabricated based on a Mg-Al layered double hydroxide (Mg-Al LDH) nanocomposite glassy carbon electrode (GCE) modified with a poly-m-amino-benzenesulfonic acid (p-m-ABSA) film. Depositing Mg-Al LDH nanocomposites onto the surface of the p-m-ABSA composite resulted in an effective electrical response by increasing the electrode surface area and enhancing the electron transfer process, so the electrocatalytic activity was significantly enhanced. The research illustrated that the fabricated sensor (Mg-Al LDH/p-m-ABSA/GCE) exhibited strong affinity, high sensitivity, and selectivity towards methyl parathion (MP) and fenitrothion (FNT). Scanning electron microscopy (SEM) was used to characterize the surface morphology of the modified electrode and showed that the p-m-ABSA film and a few p-m-ABSA nanoparticles were coated on the surface. The surface area of the electrode was further enlarged by Mg-Al LDH owing to their layered nanostructure. Under optimal conditions, the anodic current had a linear relation equal to 0.1∼20.0 µM MP and 0.01∼50.0 µM FNT, with detection limits (S/N = 3) of 33.0 nM MP and 3.5 nM FNT, respectively. Furthermore, Mg-Al LDH/p-m-ABSA/GCE was successfully used for the detection of MP and FNT in Astragalus and Magnolia medicinal herb samples.