Phenthoate is a chiral organophosphate pesticide with a pair of enantiomers which differ in toxicity, behavior and insecticidal activity, and its acute toxicity on human health owing to the inhibition of acetylcholinesterase highlights the need for enantioselective detection of enantiomers. Therefore, this study aimed to establish a simple rapid method for separation and detection of phenthoate enantiomers in fruits, vegetables and grains. The enantiomers were separated using reversed-phase high-performance liquid chromatography–tandem mass spectrometry for the first time. Rapid chiral separation (within 9 min) of the target compound was achieved on a chiral OJ-RH column with the mobile phase of methanol–water = 85:15(v/v), at a flow rate of 1 ml/min and a column temperature of 30°C. Acetonitrile and graphitized carbon black were used as the extractant and sorbent for pretreatment, respectively. This method provides excellent linearity (correlation coefficient ≥0.9986), high sensitivity (limit of quantification 5 μg/kg and limit of detection <0.25 μg/kg), satisfactory mean recoveries (76.2–91.0%) and relative standard deviation (intra-day RSDs ranged from 2.0 to 7.9% and inter-day RSDs ranged from 2.4 to 8.4%). In addition, a field trial to explore the stereoselective degradation of phenthoate enantiomers in citrus showed that (−)-phenthoate degraded faster than its antipode, resulting in the relative accumulation of (+)-phenthoate.
Qi Wang,Chao Song,Zhuang Bo,Haotong Yang,Xun Gao,Jingquan Lin
This study employed density functional theory (DFT) and time-dependent density functional theory (TD-DFT) to investigate the interaction mechanism between Phenthoate and Au20 nanoclusters, and the solvent environment effect was examined under the polarizable continuum model (PCM). By comparing and analyzing theoretical Raman active spectra and experimental Raman spectra, the phenomenon of selective enhancement of specific vibrational modes in surface-enhanced Raman spectroscopy (SERS) was explained. By analyzing the molecular structure, frontier molecular orbitals (FMOs), ultraviolet–visible absorption spectra (UV–vis), noncovalent interactions (NCI), reduced density gradients (RDG), electron localization function (ELF), and localized orbital locator (LOL), the adsorption mechanism and the spectral characteristics induced by interfacial charge transfer were comprehensively revealed at the electronic level. Phenthoate chemically adsorbed onto the Au20 surface through the S atom, forming a stable complex. Meanwhile, this charge transfer mechanism effectively modulated the polarization rate of the molecule. This study provides a theoretical basis for elucidating the adsorption behavior and spectral response mechanism of organophosphorus pesticides on metal nanostructures, offering valuable insights for the design of highly sensitive SERS sensors.
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