Hongzhe Tian

Due to the potential risks, pesticide residue analysis has attracted widespread attention. In this study, an “off‐on” fluorescence sensor for rapid detection of three target insecticide residues has been developed based on the cascade reaction system caused by acetylcholinesterase/choline oxidase dual enzyme. N and S‐doped carbon quantum dots (N, S‐CQDs) were used as the fluorescent probe. The substrate acetylcholine chloride was hydrolyzed to choline by acetylcholinesterase. Subsequently, choline oxidase oxidized the resulting choline to betaine and H ₂ O ₂ , and the generated H ₂ O ₂ quenched the fluorescence of N, S‐CQDs. The selected insecticides inhibited acetylcholinesterase activity, and therefore the sensing system's fluorescence was recovered. The linear ranges for indoxacarb, propamocarb, and fenobucarb were 3.0×10 ⁻³ –8.0×10 ⁻² mg/L, 2.0×10 ⁻³ –5.5×10 ⁻² mg/L, and 2.2×10 ⁻³ –6.5×10 ⁻² mg/L, respectively. The corresponding limits of detection ranged from 2×10 ⁻³ to 3×10 ⁻³ mg/L. For spiked concentrations between 5 µg/L and 0.1 mg/L, the average recoveries of the selected insecticides ranged from 99.6% to105%, with relative standard deviations in the range of 1.2% to 4.8%. The proposed method presents the advantages of simple operation without using requiring specialized apparatus, fast speed, low cost, and environmental friendliness. These benefits make it suitable for rapid detection of the selected insecticide residues in real samples.

Carbon quantum dots (CQDs) are considered as eco‐friendly nanomaterials and suitable alternatives for traditional metal quantum dots. However, their high hydrophilicity and nanoscale size of CQDs pose a significant risk to aquatic organisms considering their widespread application. In this study, Chlorella vulgaris was selected as a model organism to assess the ecotoxicity of CQDs synthesized using choline bitartrate via a pyrolysis method. The effects of the CQDs on algal growth, antioxidant activity, photosynthetic pigment, and malondialdehyde levels have been extensively studied. Algal growth was inhibited by CQDs with a median effective concentration (EC ₅₀ ) > 271 mg/L. After 4 days of exposure, chlorophyll content, respiratory rate, and protein content of the green alga declined by 14.0–91.75%, 73.4% and 24.4%, respectively. The CQDs caused excessive accumulation of reactive oxygen species (ROS) in Chlorella vulgaris and induced oxidative stress and physical damage to the algal cells. Our findings contribute to the potential application and risks assessment of the CQDs.

The removal of or decrease in pesticide residues in soil has attracted considerable attention, due to the serious pollution of pesticides in soil. The purpose of the study was to explore the adsorption behavior of biochar on pesticides and the impact on the degradation of pesticide residues in soil, providing a basis for the remediation of soil by biochar. Biochars were prepared via pyrolysis of rice straw at a high temperature (300 °C, 400 °C, 500 °C, 600 °C). The individual and competitive adsorption of three triazine herbicides, prometryn, atrazine, and simazine, on biochar was investigated, and the degradation of the herbicide residues in biochar-added soil was determined. The selected herbicides presented similar adsorption characteristics to rice straw biochar, and the amount of herbicides adsorbed increased with higher preparation temperature and the amount of biochar. The rice straw biochar adsorbed the studied herbicides simultaneously, and the adsorption amount decreased as follows: simazine > atrazine > prometryn. The competition adsorption of the selected herbicides on the biochar presented a lower adsorption affinity than that when they are adsorbed individually. The adsorption isotherm was best fitted by the Freundlich model. The half-lives of prometryn, atrazine, and simazine were 9.8~12.6 d, 5.2~8.1 d, and 3.7~5.6 d, respectively. Biochar addition increased the degradation of the evaluated herbicides in soil. The rice straw biochar could be the potential sorbents that can be implemented for the removal of pesticides.

The simultaneous determination of atrazine residue and its metabolites was developed using liquid chromatography-tandem mass spectrometry in Liaoning Province, China. To ensure agricultural production and environmental safety, their contamination level was assessed. A total of 2142 samples were collected between 2014 and 2020, including 1213 soil samples, 190 surface water samples, and 739 groundwater samples. The overall pollution level and detectable level of the herbicides in Liaoning Province was found to be the highest in soil followed by surface water and groundwater. The residual level of the analytes in the collected samples decreased in the following order: atrazine > hydroxyatrazine > desethylatrazine > desisopropylatrazine. From 2014 to 2020, atrazine was detected in soil and surface water, whereas hydroxyatrazine was found in soil without the selected analytes detected in groundwater. The pollution of atrazine in soil was higher than that of hydroxyatrazine, desethylatrazine, and desisopropylatrazine. To maintain sustainable agricultural development, it is critical to pay attention to the residual determination of atrazine in the environment.

The aqueous biphasic system based on choline ionic liquids and ethylene/propylene oxide copolymer coupled with high‐performance liquid chromatography‐tandem mass spectrometry was developed for the simultaneous determination of the enantiomers of two fungicides: myclobutanil and tebuconazole. The influence of mass fractions of ionic liquids and the copolymer on the extraction efficiency of the target fungicides was investigated. The analytes are mainly concentrated in the bottom, copolymer‐rich phase. The extraction efficiencies of the selected fungicides were significantly affected by the concentrations of the copolymer, and their extraction efficiencies decreased with the higher mass fractions of the copolymer, while the mass fraction of ionic liquids had little effect on their extraction behavior. Excellent extraction efficiency was achieved using the aqueous biphasic system based on choline L‐lysinate and the copolymer. At three spiked concentrations of 0.01, 0.05, and 0.1 mg/kg, the average recoveries of the selected fungicides ranged from 80 to 89%, with the relative standard deviations in the range of 2.1–5.3%. Limits of quantitation for the enantiomers of tebuconazole and myclobutanil were 0.5 and 5.0 µg/kg, respectively. The developed system could be successfully applied to the analysis of triazole fungicides residue in real samples.

Aqueous biphasic systems (ABS) composed of the choline alkanoate ionic liquids (ILs) choline acetate [Cho][OAc], choline propanoate [Cho][Pro], choline butyrate [Cho][But], and choline hexanoate [Cho][Hex], mixed with K₃PO₄ solutions at pH 7.2 and 14.5, were prepared and their phase diagrams were compared. The ability to form ABS with alkaline K₃PO₄ solutions decreased in the order [Cho][OAc] ≈ [Cho][Pro] > [Cho][But] > [Cho][Hex], while with neutral K₃PO₄ solutions, [Cho][OAc] could not form an ABS, and the other three ILs performed similarly. All of the biphasic regions of the ABS decreased with the increase in pH. ¹H-NMR data indicated anion exchange between phases in ABS at neutral pH. The ABS at neutral pH were evaluated to extract the triazine herbicides simazine, cyanazine, and atrazine, and the ABS formed by [Cho][Pro] and the pH 7.2 K₃PO₄ solution has shown extraction recoveries higher than 90%.

Aqueous biphasic systems comprising ethylene/propylene oxide copolymer (EOPO-2500) and choline acetate ([Cho][OAc]) were used for extraction of three herbicides (simazine, cyanazine, and atrazine) from aqueous samples. The influence of phase composition and temperature on phase separation as measured by tie-line lengths (TLLs) and thus, on the partition coefficient (K), of the herbicides was investigated. The herbicides preferred the EOPO-rich phase. The partition coefficients decreased with higher concentrations of EOPO-2500 and [Cho][OAc] and with increasing temperatures (i.e., K decreases with higher TLLs). The proposed system was more environment-friendly and fast compared to traditional liquid–liquid extraction, considering that no organic solvent was consumed.