In this work, a combination of QuEChERS and dispersive micro-solid phase extraction (D-μ-SPE) based on dissolvable layered double hydroxide (LDH) has been established for preconcentration and enrichment of sulfonylurea herbicides (SUHs) in wolfberry samples. The QuEChERS was used for extraction and purification of SUHs, followed by D-μ-SPE for further enrichment of targeted analytes to obtain superior extraction performance. Dissolvable LDH nanosheets were used as absorbents, thus eliminating the elution step needed in traditional D-μ-SPE. The main influence experimental variables including pH of sample solution, amount of LDH, vortex time and volume of acidic solution were optimized in detail. Under the optimized conditions, the proposed method shows high precision (RSDs < 12 .7%), low limits of detection (0.01–0.5 ng/g) and limits of quantitation (0.1–2.0 ng/g), acceptable recovery (80.1%–97.1%), thus making it a good alternative analytical strategy for the determination of SUHs residues at the low nanogram per gram range with desirable sensitivity.
The antifungal activity of six microbial-derived volatile organic compounds (VOCs) [ 3-hepten-2-one (Hep), cis-3-octen-1-ol, 3-methylvalerate, isovalerate, 1-octen-3-ol (Oct), and 2-methylbutyrate] against Aspergillus flavus was investigated by determining the minimum inhibitory concentration (MIC) and the fractional inhibitory concentration index (FICI). The results demonstrated that all 15 binary combinations of the VOCs presented additive effects against A. flavus . Among them, the combination of Hep and Oct, refers to C OH , with concentrations of 2 μL L −1 and 2.5 μL L −1 , respectively, displayed the most potent antifungal effect with the lowest concentration, in contrast to the individual MIC of Hep or Oct, which were reduced to 1/8 and 1/2. C OH can induce membrane lipid peroxidation, enhance cell membrane permeability, and cause leakage of nucleic acids and proteins within the cell, and 1-octen-3-ol might play a leading role. Finally, applying C OH at a concentration of 1/2 MIC Oct + 1/4 MIC Hep could effectively restrain the spread of A. flavus on wolfberries and exhibit excellent preservation effects. This study validates the antifungal effect of C OH and may serve as a natural alternative to antimicrobial agents for post-harvest agricultural products.
危险品化学品经营许可证（带存储）