Recent Advances in Electrochemical Determination of Pesticides.

Widespread usage of pesticides in agricultural practice caused their residues to appear in water and food products intended for human consumption. The potential toxicity of these resources has raised awareness about pesticide tracking in the environment. Development of reliable electrochemical sensors for the on-site determination of pesticide concentrations is envisioned as an alternative to conventional chromatographic methods which are robust, expensive and require skilled work force. Modification of the working electrode surface can result in enhanced electrochemical response towards selected pesticide making such electrode convenient sensor for facile and efficient determination of pesticides in low concentrations. New generation of nanomaterials is applied in electrode modification in order to improve its sensitivity and selectivity. The present review summarizes significant advances in voltammetric detection of pesticides for the period of the past five years. The major focus of this review is set to the types of carbon and oxide based materials, metal nanoparticles, composites and other materials employed to upgrade standard electrode configurations such as glassy carbon and carbon paste electrodes, boron doped diamond electrodes, screen printed and film electrodes, metal and amalgam, and other kinds of electrodes.

Multiwalled carbon nanotubes modified with MoO2 nanoparticles for voltammetric determination of the pesticide oxyfluorfen.

A glassy carbon electrode was functionalized by MoO2 nanoparticle-decorated multiwalled carbon nanotubes (MWCNTs) and examined as a working electrode in oxyfluorfen (OXY) detection by differential pulse stripping voltammetry (DPSV). Measurement parameters were as follows: initial potential - 0.1 V, end potential + 0.5 V, accumulation potential - 0.15 V, accumulation time 80 s, and scan rate 50 mV s-1. A stripping potential of + 0.315 V vs. Ag/AgCl was employed. The pPesticide oxyfluorfen was determined in model samples by DPSV with good reproducibility (RSD <2.4%) in the concentration range 2.5 to 34.5 ng mL-1, with r = 0.99 and a limit of detection of 1.5 ng mL-1. These results are in the same range as those of HPLC/DAD, which is used as the comparative method. Recovery for OXY determination in a real river water sample was 102%. Analyses in Briton-Robinson buffer has shown to be pH dependent with the best response at pH 6.0. Structural characterization of MoO2-MWCNT by Raman spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray crystallography revealed a preserved MWCNT structure decorated with firmly attached clusters of MoO2 nanoparticles. Graphical abstract Glassy carbon electrode functionalized by MoO2 nanoparticle-decorated multiwalled carbon nanotubes is used as a working electrode in the voltammetric determination of pesticide oxyfluorfen in water.

The Targeted Pesticides as Acetylcholinesterase Inhibitors: Comprehensive Cross-Organism Molecular Modelling Studies Performed to Anticipate the Pharmacology of Harmfulness to Humans In Vitro.

Commercially available pesticides were examined as Mus musculus and Homo sapiens acetylcholinesterase (mAChE and hAChE) inhibitors by means of ligand-based (LB) and structure-based (SB) in silico approaches. Initially, the crystal structures of simazine, monocrotophos, dimethoate, and acetamiprid were reproduced using various force fields. Subsequently, LB alignment rules were assessed and applied to determine the inter synaptic conformations of atrazine, propazine, carbofuran, carbaryl, tebufenozide, imidacloprid, diuron, monuron, and linuron. Afterwards, molecular docking and dynamics SB studies were performed on either mAChE or hAChE, to predict the listed pesticides' binding modes. Calculated energies of global minima (Eglob_min) and free energies of binding (∆Gbinding) were correlated with the pesticides' acute toxicities (i.e., the LD50 values) against mice, as well to generate the model that could predict the LD50s against humans. Although for most of the pesticides the low Eglob_min correlates with the high acute toxicity, it is the ∆Gbinding that conditions the LD50 values for all the evaluated pesticides. Derived pLD50 = f(∆Gbinding) mAChE model may predict the pLD50 against hAChE, too. The hAChE inhibition by atrazine, propazine, and simazine (the most toxic pesticides) was elucidated by SB quantum mechanics (QM) DFT mechanistic and concentration-dependent kinetic studies, enriching the knowledge for design of less toxic pesticides.