Nanocarbon-based sensors for pesticide detection: Recent trends

A Simple and Novel Sensor for the Determination of Acetamiprid Based on Its Reducing Effect on the Chemiluminescence of S, N-CQDs in CH3CN-H2O2 System

A simple and novel method for the determination of acetamiprid in water samples is suggested. The method is based on the reducing effect of acetamiprid on the chemiluminescence intensity of new sulfur and nitrogen co-doped carbon dots (S, N-CQDs) in an acetonitrile-hydrogen peroxide (CH₃CN-H₂O₂) system. The possible mechanism was investigated, and it was found that S, N-CQDs react with (¹O₂)₂*, produced from the CH₃CN-H₂O₂ reaction, leading to excited state S, N-CQDs, which deactivate to the ground state by photon emission. Acetamiprid diminishes the chemiluminescence (CL) intensity by competing with S, N-CQDs. The CL intensity reduction is proportional to the concentration of acetamiprid. S, N-CQDs were easily prepared by a hydrothermal method. Under the optimal conditions, a linear range of 2.5 - 25.0 μg L^-1 with a detection limit (3σ) of 0.4 μg L^-1 was obtained. This method was successfully applied to the determination of trace amounts of residual pesticides in water samples.

A non-mercury electrode for the voltammetric determination of butralin in foods

A modified electrode was developed with Co-Ag bimetallic nanoparticles stabilized in poly(vinylpyrrolidone) for butralin monitoring. This is the first non-mercury electrode proposed for the quantification of butralin. The bimetallic nanoparticles were characterized by spectroscopic and microscopic techniques, which showed that they are composed of a cobalt core partially covered with silver. The modified electrode was characterized by field emission gun scanning electron microscopy, energy dispersive X-ray spectroscopy and electrochemical impedance spectroscopy. The experimental parameters (pH, supporting electrolyte, accumulation step, pulse technique) were optimized. The calibration plot for butralin obtained by square wave voltammetry was linear in the range of 0.1-1.0 μmol L^-1 with limits of detection and quantification of 32 and 106 nmol L^-1, respectively. Lastly, the modified electrode was effectively implemented in the quantification of butralin in honey and apple jam samples. The results were in agreement with those furnished by UV-vis spectrometry and endorsed by statistical tests.