Determination of pesticides using a low-temperature co-fired ceramic microfluidic platform

The aim of this work is the integration of an improved graphite–epoxy composite electrode modified with the acetylcholinesterase enzyme as a detector into a green tape ceramic microfluidic device for the online amperometric determination of pesticides. First, the operational conditions of the microfluidic system were optimized for the enzymatic substrate determination of acetylthiocholine. Good results were achieved for acetylthiocholine determination, obtaining a low detection limit and optimal sensitivity. The analytical performance of the microanalyzer was evaluated with organophosphorus and carbamate pesticides across a wide concentration range. Pesticides were determined indirectly measuring the enzymatic inhibition effect that they caused. The analysis was based on stopped-flow methodology with a three-step strategy: enzymatic substrate measurement, enzymatic inhibition by pesticide contact with the biosensor, and enzymatic substrate measurement after the inhibition process. The pesticide concentrations were determined by the percentage of inhibition produced. The microanalyzer was used for the analysis of spiked irrigation water samples using this indirect method. The low-temperature co-fired ceramic/epoxy–graphite–acetylcholinesterase microfluidic system showed low limits of detection and adequate sensitivity. The recoveries of the spiked water samples were approximately 100% with relative standard deviation values lower than 5% for three replicate measurements. All results obtained are indicative of a convenient, rapid, sensitive, and economic method for the determination of pesticides in environmental samples.