Abstract

A sensitive and ratiometric electrochemical biosensor was developed for the determination of dimethoate via alkaline phosphatase (ALP) mediated dissolution of nano-MnO2 and [Ru(NH3)6]3+(Ru(III)) redox recycling. The electroactive probe Ru(III) was adsorbed on the nano-MnO2 with the high specific surface area through electrostatic interaction to form the MnO2-Ru(III) nanocomposite, which was then fixed on the surface of the glassy carbon electrode. When the dimethoate inhibited the catalytic activity of ALP in a homogeneous system, the hydrolysate L-ascorbic acid (AA) produced by ALP hydrolysis of L-ascorbic acid-trisodium 2-phosphate (AAP) decreased. The solution was then incubated with a glassy carbon electrode modified by MnO2-Ru(III). At this time, only a small amount of MnO2-Ru(III) was decomposed and Ru(III) was rapidly electroreduced to Ru(II) on the surface of the electrode. The in-situ produced Ru(II) was chemically oxidized back to Ru(III) by Fe(III). The redox recycling of Ru(III) was completed and the Ru(III) reduction current signal was amplified. The process consumed part of Fe(III) to reduce the reduction current signal of Fe(III), and the ratio of the two reduction currents (IRu(III)/IFe(III)) increased significantly. The IRu(III)/IFe(III) value increased with the increase of dimethoate concentration in the linear range of 0.01–300 ng mL−1, and the detection limit was 6.3 pg mL−1. It has been successfully applied to the determination of dimethoate in oilseed rape and lettuce with a satisfactory result.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.