The large increase in the herbicides tolerant plants has dramatically affected the level of usage of these herbicides recently. There exists an increasing concern about the associated toxicity to the environmental and human health, which instills a need for direct low concentration detection of these herbicides present in various drinking water, food and crop products. In this work, we present the deconstruction of a simple, label-free electrochemical sensor to selectively detect glyphosate. The mapping of the pesticide levels in sample is probed and detected using two electrochemical modalities: Non-Faradaic Electrochemical Impedance Spectroscopy (EIS)-due to its ability to map the subtle chemical interactions occurring at the electrode-electrolyte interfacial double layer and Chronoamperometry (CA)-utilized due to its depiction of transient current representative of the binding effects seen in this affinity biosensing methodology. The study’s first focus deals with surveying the effect of the different immobilization steps onto the gold substrate (electrode) by validating the immunochemistry and the binding between the receptor agent and the glyphosate analyte. Next, the temporal factor of incubation and thereby response time is evaluated to optimize the sensor system. Finally, in order to build an overall end-to-end sensing ecosystem: a robust machine learning classification algorithm is integrated to increase the accuracy and precision of the pesticide residue level results. Overall, the sensor has been proven to measure the spiked pesticides doses in real food/water samples with the low limit of detection of 1ppb. The sensing platform therein can be summarized as a micro-volume, high-sensitive, and selective platform which requires no prior sample preparation with the cross-functional ability of machine learning classification. Hence, it can be a potentially game-changing electrochemical on-field sensing device to measure trace pesticide residues against a threshold limit (as given by various environmental agencies worldwide)-as a precautionary step to alert the common man using the food products as well as farmers working in the agriculture field.

Electrochemical teardown of a trace pesticide assessment system

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.