Pesticide residues identification by impedance time-sequence spectrum of enzyme inhibition on multilayer paper-based microfluidic chip

Different organophosphorus pesticides (OPs) normally vary in the level of toxicity to human health, but common electrochemical identification methods usually require complex electrode fabrication processes and high detection cost. To overcome these problems, a pesticide residues identification method based on multilayer paper-based microfluidic chip was proposed. The microfluidic chip integrates the enzyme inhibition and a label-free screen-printed carbon electrode (SPCE). Three different pesticides were selected as study objects, respectively, avermectin, phoxim, dimethoate. This chip realizes on-chip identification via analyzing impedance time-sequence spectrum data aroused by the enzyme inhibition during the 15 min period. A classification model based on principal component analysis (PCA) and support vector machines (SVMs) was established to evaluate these data. Furthermore, the real-world sample (lettuce) was tested to verify the feasibility of the proposed detection method. The results showed that the classification accuracy was achieved around 93% in multiple experiments. Therefore, the method has good stability and specificity in rapid identification of different pesticides. Practical Applications Identification of pesticide types is essential to human health, for this, impedance time-sequence spectrum data aroused by the enzyme inhibition during the 15 min period was used to establish a classification model to identity different types of pesticides. In this article, multilayer paper-based microfluidic chip and a label-free screen-printed carbon electrode (SPCE) was proposed without complicated operation steps and expensive cost, which provide a basis for establishment of the rapid pesticide discriminator.