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• PPy combined with MIL-53 into multilayer composites as a new magnetic adsorbents. • Adsorbent extraction of triazole fungicides has a wider range of optimal pH. • A method for analyzing triazole residues was established based on MSPE and HPLC. • Method successfully applied to three fruit juices and two environmental waters. In this work, a magnetic adsorption material based on a metal–organic framework (Fe 3 O 4 @PPy@MIL-53(Fe)) was designed and prepared, as well as used as an adsorbent for the extraction of fungicides from fresh juice and environmental water. The material was subjected to a series of characterization analyses, which showed that the material has good potential for application as an adsorbent. The main parameters such as adsorbent dosage, adsorption time, elution time, pH value, and elution solvent which could affect the experiment results were optimized. Under optimal conditions, the method exhibited linearity (R2 ≥ 0.9994) in the concentration range 10–1000 µg/L for three triazole fungicides, and LOD value ranged from 2.1 µg/L to 2.9 µg/L. In addition, the established method was applied to real samples of three fruit juices and two ambient waters, and satisfactory recoveries in the range of 78.6%-105.4% and RSDs of ≤ 5.7% were obtained. [ABSTRACT FROM AUTHOR]

[Display omitted] • Magnetic core–shell Fe 3 O 4 @DUT-5 was prepared as MSPE adsorbent. • The method delivered low LOD, good recoveries and satisfactory precision. • Fe 3 O 4 @DUT-5-MSPE-HPLC method proved to be effective and economical. A sample pre-treatment technology, based on magnetic MOF composite Fe 3 O 4 @DUT-5 as the adsorbent, combined with high performance liquid chromatography (HPLC) has been developed and used for the trace analysis of azole fungicide residues in fruits and vegetables. Characterization analysis shows that Fe 3 O 4 @DUT-5 has good stability and excellent saturation magnetism. Under the optimal conditions, the satisfactory enrichment factors (69.6–96.4), and good linearity (10–1000 μg L-1) could be achieved, as well as the low limits of detection (0.054 to 0.313 μg L-1) were proved to be below the maximum residue limits (MRLs) of azole fungicides in agricultural products (10.0 μg kg−1). Additionally, the proposed method has been successfully applied to the determination of target analytes in six fruits and vegetables. The achieved recovery (62.3–100.8%) and reproducibility (lower than 6.4%) meet the requirements of pesticide residue analysis. Moreover, the high adsorption capacity and stability remain unchanged after 5 cycles. And it has a strong saturation magnetization value, which provides a strong guarantee for recycling. As a novel adsorbent, Fe 3 O 4 @DUT-5 showed great potential in the extraction of pesticide residues in fruits and vegetables. [ABSTRACT FROM AUTHOR]

• Dihydroxyindole, anthranilic acid, N-acetylanthranilic acid significantly discriminated the three treatments. • Low nitrogen generally led to the decrease of most amino acids and the increase of phenylalanine, indole-3-pyruvate acid, and some specialized metabolites. • Low nitrogen treatments induce the accumulation of active ingredients in Isatis leaf, such as quercetin, indigo and indirubin. • The change in content of indole-3-acetic acid (IAA) was speculated to be the potential low nitrogen tolerance mechanism of I. indigotica. Isatis indigotica Fortune represents a significant economic resource in China, which the leaves (Daqingye) remain until now important and popular herbal drug in traditional Chinese medicine (TCM). Nitrogen nutrition is in great demand during plant growth stage, and nitrogen levels are usually related with plants biosynthesis of primary and secondary metabolites. To investigate the influence of nitrogen nutrition levels on various metabolites of Isatis leaf, untargeted metabolomics analysis based on LC–MS (UPLC-Triple-TOF system) was used to obtain the response of Isatis leaf under different nitrogen levels: 0 mmol·L−1(deficient), 7.5 mmol·L−1 (low) and 15 mmol·L−1 (high). Based on the results, dihydroxyindole, anthranilic acid, N-acetylanthranilic acid significantly discriminated the three treatments. Low nitrogen generally led to the decrease of most amino acids, while the increase of phenylalanine, indole-3-pyruvate acid, and some specialized metabolites including quercetin, indigo and indirubin were observed. The change in content of indole-3-acetic acid (IAA) was speculated to be the potential low nitrogen tolerance mechanism of I. indigotica. Our findings suggest that nitrogen levels significant affect metabolic capacity of Isatis leaf; low nitrogen treatments induce the accumulation of active ingredients. This result will provide leads into understanding the physiological adaption to nitrogen levels of Isatis leaf and quality improvement research of Daqingye. [ABSTRACT FROM AUTHOR]

Isatis indigotica Fortune is a popular herb in traditional Chinese medicine, and various types of metabolites are the basis for its pharmacological efficacy. The biosynthesis and accumulation of these metabolites are closely linked to nitrogen availability; the benefits of low nitrogen application on the environment and herb quality are increasingly prominent. To analyze metabolic changes in the leaves and roots of I.indigotica in nitrogen deficiency conditions, and to identify the pathways and metabolites induced by low nitrogen availability, we used untargeted liquid chromatography coupled with mass spectrometry (UHPLC-TripleTOF) to obtain metabolomics profiling of I.indigotica under two N-deficiency treatments (0 kg/hm2; 337.5 kg/hm2) and normal nitrogen treatment (675 kg/hm2). A total of 447 metabolites were annotated. Principal component analysis separated the three nitrogen treatments. A greater diversity of metabolites was observed in roots than in leaves under N-deficiency treatments, suggesting that roots have a more important function in low N tolerance. Differential metabolites were mainly enriched in purine metabolism, phenylpropanoid biosynthesis, the shikimate pathway, tryptophan metabolism, and flavonoid biosynthesis that notably induced only in leaves in low nitrogen stress. Moderate N-deficiency benefits carbohydrate accumulation, whereas accumulation of most amino acids decreases. Uniquely, L-tryptophan was maintained at a high concentration in N-deficiency conditions. Low nitrogen stress induced the accumulation of some specialized metabolites (matairesinol, dictamnine, 5-hydroxyindoleacetate (serotonin) in roots and vitexin, xanthohumol, sinapyl alcohol in leaves). N-deficiency also increased the accumulation of adenosine and quality indicators of I.indigotica (indirubin-indigo, epigoitrin and anthranilic acid) in a certain degree. Our findings showed that nitrogen deficiency modified roots and leaves conditions of I.indigotica , affecting both the primary and secondary metabolism. Moderate nitrogen reduction was beneficial to the accumulation of active ingredients. Our methods and analysis are expected to provide an insight regarding the diversity of metabolites and regulation of their synthesis in low nitrogen application, and better investigate the nitrogen deficiency effect on I.indigotica. Image 1049134 • A greater diversity of metabolites was observed in roots than in leaves under N-deficiency treatments. • Differential metabolites were mainly enriched in purine metabolism, phenylpropanoid biosynthesis, the shikimate pathway, and tryptophan metabolism. • Flavonoid biosynthesis was significantly induced only in leaves. • Moderate N deficiency benefits carbohydrate and specialized metabolites accumulations, whereas decrease the most amino acid accumulation (except for L-tryptophan). • N-deficient treatments induced the synthesis and accumulation of quality indicators (indigo-indirubin, epigoitrin and anthranilic acid) in a certain degree. [ABSTRACT FROM AUTHOR]

Studies on the differences between chiral pesticide enantiomers have caused widespread concern in the last decade. In the current work, the selective behaviors and different biological activities of paclobutrazol enantiomers during Chinese cabbage pickling process were evaluated. Results of degradation kinetics indicated that when paclobutrazol reside in raw material (Chinese cabbage) and was introduced into the pickling process, the degradation rates of the two paclobutrazol enantiomers were significantly different, the half‐lives of (2R, 3R)‐paclobutrazol (R‐paclobutrazol) and (2S, 3S)‐paclobutrazol (S‐paclobutrazol) were 18.24 and 6.19 d, respectively. Besides, the conversion between the two enantiomers could also be observed, and the conversion rate of R‐paclobutrazol to S‐paclobutrazol was slower than that of reverse process. In addition, from the analysis of 16S rRNA and ITS sequencing, we inferred that the degradation of paclobutrazol was probably due to the presence of Pseudomonas and Serratia. Moreover, there has a significant difference in biological activity between R‐paclobutrazol and S‐paclobutrazol and shown an obviously enantiomeric effects on microbial community composition of pickling system. Besides, the analysis of microbial community displayed R‐paclobutrazol might inhibit the growth of Erwinia (a sort of plant pathogens). Results from this study served to enhance our understanding of chiral pesticide residues on food safety and the potential risks to human health. [ABSTRACT FROM AUTHOR]

Agricultural plastic films and triazole fungicides are widely used in agricultural production process. Exposure to natural environment, agricultural plastic films will degrade into micron plastic particles, which will adsorb pesticide molecules and may affect their toxicity, biological activity and persistence. The long-term coexistence of microplastics (MPs) and triazole fungicides will bring potential harms to the agricultural ecological environment. Therefore, two kinds of triazole fungicides flusilazole (FLU) and epoxiconazole (EPO) were selected as cases and the adsorption behaviors of them on polystyrene and polyethylene were investigated. A series of factors which could affect the adsorption behavior were evaluated. Specifically, the particle size of MPs could affect its adsorption capacity, and the smaller the particle size, the stronger the adsorption capacity. Moreover, with the increase of pH value from 6.0 to 9.0, the adsorption capacity of MPs to target compounds gradually increased. The effect of ionic strength was evaluated by NaCl, and 0.05% of NaCl was beneficial to the adsorption process, while the continuous increase of NaCl concentration inhibited the adsorption. Oxalic acid and humic acid decreased the adsorption capacity of flusilazole on PE by 15.99–32.00% and PS by 35.02–48.67%, respectively. In addition, compared with the single pesticide system, the adsorption capacity of MPs for flusilazole and epoxiconazole in the binary pesticides system decreased by 36.13–37.93% and 44.36–51.35%, respectively, indicating that competitive adsorption occurred between the two pesticides. Meanwhile, the adsorption process was evaluated by adsorption kinetics and adsorption isotherms and were consistent with pseudo-second-order kinetic model and Freundlich isotherm model, respectively. Finally, several characterization analyses were conducted to investigated the adsorption mechanism, and hydrogen, halogen bonding and hydrophobic interaction proved to play an important role. The study on the adsorption behavior and mechanism of pesticide on MPs was the basis of assessing the risk of joint exposure. [Display omitted] • The adsorption capacity of the same pesticide on PE was higher than that on PS. • The adsorption capacity of FLU was higher than EPO on the same MPs. • In the binary pesticide system, competitive adsorption occurred between pesticides. • Adsorption mechanisms include hydrogen, halogen bonds, and hydrophobic interactions. [ABSTRACT FROM AUTHOR]

[Display omitted] • The introduction of ZIF-90 forms a magnetic double MOF material. • Azole fungicides adsorption was thermodynamically feasible and followed pseudo second order kinetics. • Maximum adsorption capacity was 352.32 mg g−1. • The Fe 3 O 4 @ZIF-90@MIL-68(Al) showed good regeneration function. In this study, Fe 3 O 4 @ZIF-90@MIL-68(Al) composite was synthesized by a facile method and used as a reusable adsorbent to effectively remove azole fungicides from paddy field water. Notably, the introduction of ZIF-90 made the magnetic adsorbent more stable and significantly improved the adsorption performance. Specifically, a series of characterization analysis were carried out and this composite displayed a high specific surface area, excellent magnetic strength, and good thermal stability, which meet the expectations. Additionally, the adsorption behaviors and mechanisms of Fe 3 O 4 @ZIF-90@MIL-68(Al) toward azole fungicides were studied systematically. The pseudo-second-order kinetic model and Langmuir isotherm model was confirmed to be more suitable for describing this adsorption process. Besides, the adsorption process of azole fungicides onto Fe 3 O 4 @ZIF-90@MIL-68(Al) was mainly based on pore filling, surface complexation, covalent bonding, π-π stacking effect and hydrogen bonding. Interestingly, the maximum adsorption capacity of Fe 3 O 4 @ZIF-90@MIL-68(Al) toward prochloraz was 352.32 mg g−1, which was probably one of the highest adsorption capacities reported. Meanwhile, the magnetic adsorbent can be regenerated by methanol treatment and maintain a high adsorption capacity after the 10th cycle. Hence, this work provides an economical and feasible method for removing azole fungicides from field water samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • Magnetic cyclodextrin polymers were synthesized and used as an adsorbent. • A modified method for the analysis of azole pesticides in medicinal plants. • The proposed method was proved to be simple, rapid, and economical. In this work, a sensitive and cost-effective method for the quantitative analysis of azole pesticides residues in six medicinal plants was established based on magnetic cyclodextrin crosslinked with tetrafluoroterephthalonitrile (Fe 3 O 4 @TFN-CDPs) coupled with high-performance liquid chromatography (HPLC). Through characterization analysis, the outer shell of Fe 3 O 4 @TFN-CDPs has observed coating with a network of the polymer and forming a core–shell structure. Under the optimum conditions, the limits of detection (LODs) and limits of qualification (LOQs) of target pesticides were ranged from 0.011 to 0.106 µg Kg−1 and from 0.036 to 0.354 µg Kg−1, respectively. Finally, the achieved recoveries of pesticides in six medicinal samples fluctuated from 60.1% to 102.3%. Altogether, this method based on Fe 3 O 4 @TFN-CDPs composites provided a new idea for the analysis of trace pesticides in complicated matrices. [ABSTRACT FROM AUTHOR]