Simultaneous Enantioselective Determination of Two New Isopropanol-Triazole Fungicides in Plant-Origin Foods Using Multiwalled Carbon Nanotubes in Reversed-Dispersive Solid-Phase Extraction and Ultrahigh-Performance Liquid Chromatography-Tandem Mass Spectrometry

Recent Progress in Detecting Enantiomers in Food

The analysis of enantiomers in food has significant implications for food safety and human health. Conventional analytical methods employed for enantiomer analysis, such as gas chromatography and high-performance liquid chromatography, are characterized by their labor-intensive nature and lengthy analysis times. This review focuses on the development of rapid and reliable biosensors for the analysis of enantiomers in food. Electrochemical and optical biosensors are highlighted, along with their fabrication methods and materials. The determination of enantiomers in food can authenticate products and ensure their safety. Amino acids and chiral pesticides are specifically discussed as important chiral substances found in food. The use of sensors replaces expensive reagents, offers real-time analysis capabilities, and provides a low-cost screening method for enantiomers. This review contributes to the advancement of sensor-based methods in the field of food analysis and promotes food authenticity and safety.

Simultaneous determination of spiropidion and its five major metabolites in sweet orange fruit and various processing by-products using ultra-high performance liquid chromatography-tandem mass spectrometry

The present work reported the application of an ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for simultaneous analysis of spiropidion and its five major metabolites in sweet orange fruit and by-products throughout the whole industrial juicing process of the orange fruit. The reversed-dispersive solid phase extraction (r-DSPE) with multi-walled carbon nanotubes (MWCNTs) was employed for the extraction and purification. The established method was validated and satisfactory parameters (linearity, trueness, precision, sensitivity, matrix effect and stability) were obtained. And then, the field trial of spiropidion on sweet oranges has been conducted and the effect of commercial juicing processing on the residue of spiropidion and its metabolites was further investigated. The various processing factors (PFs) for washing, juicing, sterilization, concentrating and essential oil collecting were also determined. The final results indicated that washing processing reduced residues by 18.4%; the juicing step allowed a significant decrease of the spiropidion residue by 34.2-70.8%, with PFs value in the range of 0.290-0.658. However, high level of residual spiropidion (ranging from 4.016 to 4.205 mg/kg) was detected in orange essential oil, with PFs value of 17.157. All the above results demonstrated the efficiency of the established method in the routine control analysis of spiropidion residues in sweet orange fruits and their by-products, and will facilitate the further intensive research on its spatial distribution, transfer and degradation during the different processing procedures of the sweet orange fruits.

Slice-layer COFs-aerogel: a regenerative dispersive solid-phase extraction adsorbent for determination of ultra-trace quinolone antibiotics

A novel type of three-dimensional network structure, covalent organic frameworks (COFs) aerogel, was fabricated and applied to dispersive solid-phase extraction (dSPE) of quinolone antibiotics (QAs). Density functional theory (DFT) was applied to investigate the possible interaction mechanism and results confirmed that the strong adsorption affinity is attributed to the intralayer hydrogen bonds and π-π interaction. Furthermore, a sensitive analytical method based on COFs-aerogel for determining quinolone antibiotics residues in water and honey samples was developed and HPLC-MS/MS was used for sample detection and quantification. Under the optimal conditions, COFs-aerogel exhibited a wide linearity (0.1-500 ng∙L-1), low limits of detection (0.02-0.06 ng∙L-1), and good precision (RSD ˂ 10%) for selected QAs. A preliminary practical application of the developed method was proved by the efficient detection of quinolone antibiotics in water and food samples with good recoveries (68.2-104% and 64.0-100% for water and honey samples, respectively). Combining the experimental data with theoretical calculation, results illustrated that COFs-aerogel holds a great potential to capture contaminants and address environmental and food safety issues.

Enantioselective Behaviors of Chiral Pesticides and Enantiomeric Signatures in Foods and the Environment

Unreasonable application of pesticides may result in residues in the environment and foods. Chiral pesticides consist of two or more enantiomers, which may exhibit different behaviors. This Review intends to provide progress on the enantioselective residues of chiral pesticides in foods. Among the main chiral analytical methods, high performance liquid chromatography (HPLC) is the most frequently utilized. Most chiral pesticides are utilized as racemates; however, due to enantioselective dissipation, bioaccumulation, biodegradation, and chiral conversion, enantiospecific residues have been found in the environment and foods. Some chiral pesticides exhibit strong enantioselectivity, highlighting the importance of evaluation on an enantiomeric level. However, the occurrence characteristics of chiral pesticides in foods and specific enzymes or transport proteins involved in enantioselectivity needs to be further investigated. This Review could help the production of some chiral pesticides to single-enantiomer formulations, thereby reducing pesticide consumption as well as increasing food production and finally reducing human health risks.

Magnetic deep eutectic solvent-based dispersive liquid-liquid microextraction for enantioselectively determining chiral mefentrifluconazole in cereal samples via ultra-high-performance liquid chromatography

A simple, rapid, and efficient pretreatment method of mefentrifluconazole enantiomers in cereal samples was established by dispersive liquid-liquid microextraction coupled with ultra-high-performance liquid chromatography-diode array detector (UHPLC-DAD). In this study, a novel ternary magnetic deep eutectic solvent (MDES) [octyltrimethylammonium bromide][cobalt chloride][acetic acid] was synthesized as the extractant. Acetic acid was used as the dispersant to promote the in situ dispersion of binary MDES [octyltrimethylammonium bromide][cobalt chloride]. The microdroplets of binary MDES containing mefentrifluconazole were separated by an external magnet. Device-assisted dispersion and time-consuming centrifugation steps were eliminated to ensure simplicity and rapidity of the pretreatment. Good linearity ranging from 0.01 μg g^-1 to 2 μg g^-1 was obtained. The extraction recovery varied from 82.9 to 95.0%. The limit of detection was 0.003 μg g^-1. Finally, this established approach has been applied for the enantioselective detection of chiral mefentrifluconazole in corn, rice, wheat, millet, and sorghum samples.

Enantioselective toxic effects of mefentrifluconazole in the early life stage of zebrafish (Danio rerio)

The research on the enantioselective toxic effects of chiral pesticides on non-target aquatic organisms has attracted more and more attention. This study investigated the enantioselective toxic effects of mefentrifluconazole (MFZ) on acute toxicity, developmental toxicity, locomotor behaviors, and the mRNA relative expression levels of genes related to neurodevelopment and cardiac development in zebrafish embryos or larvae. The 96-h lethal concentration 50 (LC₅₀ ) values (exposed to racemate and enantiomers of MFZ, that is, rac-MFZ/(-)-MFZ/(+)-MFZ) were 1.010, 1.552, and 0.753 mg/L for embryo, and 0.753, 1.187, and 0.553 mg/L for larvae. The rac-MFZ/(-)-MFZ/(+)-MFZ can affect the heart development of zebrafish embryos, accompanied by heart rate inhibition, yolk sac deformities, pericardial deformities, and down-regulation of genes related to cardiotoxicity in larvae in an enantioselective manner. Moreover, the rac-MFZ/(-)-MFZ/(+)-MFZ also can affect the neural development of zebrafish embryos, accompanied by autonomic movement inhibition, swimming speed and swimming distance abnormalities, and down-regulation of genes related to neurotoxicity in larvae in an enantioselective manner. For all toxicity endpoints, the effect of the (+)-MFZ to early-staged zebrafish were significantly greater than that of (-)-MFZ. These results will help distinguishing the difference of MFZ enantiomers to zebrafish, and provide scientific reference for improving the risk assessment of chiral pesticides MFZ.

Simultaneous determination of pyflubumide and its metabolite in vegetables and fruits by ultrahigh performance liquid chromatography-tandem mass spectrometry

A rapid and cost-effective analytical method based on ultrahigh-performance liquid chromatography-tandem mass spectrometry was designed and verified for simultaneously monitoring the novel acaricide pyflubumide and its metabolite (pyflubumide-des(2-methyl-1oxopropyl)) in vegetables and fruits. After the extraction with acetonitrile, the samples were purified by dispersive solid phase extraction with multi-walled carbon nanotubes. Detection of the two target analytes was achieved within 3.0 min using a positive electrospray ionization mode. The average recovery, intra-day precision and inter-day precision of the two analytes at three spiked levels (2, 20 and 100 μg/kg) were 75.0%-101.0%, 0.4%-4.4% and 0.6%-5.3%, respectively. The limit of quantification of two compounds was 2 μg/kg, which was far below the maximum residue limits of pyflubumide in foods established by Japan and South Korea. Finally, the concentrations of pyflubumide and its metabolite in the samples were 16.6 and 7.8 μg/kg respectively, which verified the practicability and reliability of the method. The method was used to efficiently detect pyflumide and its metabolite in real samples, and was confirmed to be robust and effective for routinely analyzing both pyflubumide and its metabolite in vegetable and fruit samples. This article is protected by copyright. All rights reserved.

Enantioselectivity of new chiral triazole fungicide mefentrifluconazole: Bioactivity against phytopathogen, and acute toxicity and bioaccumulation in earthworm (Eisenia fetida)

Elaborating the environmental behavior of mefentrifluconazole, a novel triazole fungicide, in stereoselective level is of paramount importance for the application of the pesticide in agriculture. In this study, the enantioselective bioactivity, acute toxicity and stereoselective bioaccumulation of mefentrifluconazole in earthworm (Eisenia fetida) were investigated. Bioactivity tests against four pathogens revealed that R-(-)-mefentrifluconazole exhibited approximately 11-113 times higher bioactivity than its S-(+)-mefentrifluconazole. However, the LC₅₀ of S-(+)-, rac- and R-(-)-mefentrifluconazole to earthworm was measured to be 4.1, 11.4 and 7.3 μg/cm², respectively, indicating active ingredient R-(-)-mefentrifluconazole is less toxic than its racemate and S-form. Accumulation of mefentrifluconazole in earthworms was non-enantioselective and negatively related to its adsorption onto soils. The concentration of mefentrifluconazole in in situ pore water (C_IPW) and CaCl₂ extraction (C_CaCl2) was closely related to its accumulation in earthworms, suggesting that C_IPW and C_CaCl2 could be appropriate indicators for estimation of the bioavailability of mefentrifluconazole in soil. Conclusively, our study provides necessary information for the risk assessment of mefentrifluconazole in agriculture.

The sexual reproduction of the nontarget planarian Girardia tigrina is affected by ecologically relevant concentrations of difenoconazole: new sensitive tools in ecotoxicology

The fungicide difenoconazole, widely used to reduce the negative impacts of fungi diseases on areas with intensive farming, can reach freshwater systems causing deleterious effects on nontarget organisms. The acute and chronic toxicity of a commercial formulation containing 250 g L^-1 of difenoconazole (Prisma®) as the active ingredient was assessed in the freshwater planarian Girardia tigrina. The endpoints evaluated were feeding rate, locomotion, regeneration, and sexual reproduction of planarians. The estimated 48 h LC₅₀ of the commercial formulation on planarians expressed as the concentration of the active ingredient difenoconazole was 47.5 mg a.i.L^-1. A significant decrease of locomotion (LOEC = 18.56 mg a.i.L^-1), delayed regeneration (LOEC = 9.28 mg a.i.L^-1), and sexual reproduction impairment, i.e., decreased fecundity and fertility rates (LOEC ≤ 1.16 mg a.i.L^-1) were observed on planarians exposed to sublethal concentrations of the formulation. This study demonstrated the importance of using reproductive, physiological, and behavioral parameters as more sensitive and complementary tools to assess the deleterious effects induced by a commercial formulation of difenoconazole on a nontarget freshwater organism. The added value and importance of our research work, namely, the impairment of sexual reproduction of planarians, contributes to the development of useful tools for ecotoxicology and highlights the fact that those tools should be developed as guidelines for testing of chemicals. Our results showed that the use of reproductive parameters of Girardia tigrina would help to complement and achieve a better assessment of the risk posed by triazole fungicides to freshwater ecosystems.

Chiral fungicide penconazole: Absolute configuration, bioactivity, toxicity, and stereoselective degradation in apples

Traditional evaluation of chiral pesticides can lead to inaccurate results, as their enantiomers may show different properties. Penconazole, a chiral triazole fungicide with two enantiomers, is widely applied to protect against phytopathogens. In this study, its absolute configuration, bioactivity, ecotoxicity, and stereoselective degradation were investigated at the enantiomeric level in detail. The absolute configuration of the two enantiomers (R-(+)-penconazole and S-(-)-penconazole) was first confirmed by electronic circular dichroism (ECD), and their enantioseparation method was developed and optimized using UPLC-MS/MS. S-(-)-penconazole showed high bioactivity, as its fungicidal activity against four target phytopathogens (Alternaria alternate f. sp. mali, Botryosphaeria berengeriana f. sp. piricola, Colletotrichum gloeosporioides, and Fusarium oxysporum) was 1.8-4.4 times higher than that of R-(+)-penconazole. The results of an acute toxicity test showed that the LC₅₀ values of S-(-)-penconazole against Daphnia magna were 32.5 times higher than those of R-(+)-penconazole at 24 h during the test period. Stereoselective degradation behaviors were found in nonbagging and bagging Fuji apples collected from three major apple-producing regions in China, with half-lives of 23.5-51.6 d (nonbagging treatment) and 23.0-57.5 d (bagging treatment) for R-(+)-penconazole and 41.1-60.9 d (nonbagging treatment) and 52.5-91.2 d (bagging treatment) for S-(+)-penconazole, respectively. This study provided new insights into the bioactivity, ecotoxicity, and stereoselective degradation of penconazole enantiomers. The above results also emphasized the importance of risk assessments of chiral pesticides at the enantiomeric level.

Enantioselective toxic effects of mefentrifluconazole in the liver of adult zebrafish (Danio rerio) based on transcription level and metabolomic profile

Mefentrifluconazole, a new type of chiral triazole fungicide, is widely applied to control a variety of fungal diseases in crops. However, the toxicological effects of mefentrifluconazole on aquatic organisms are unknown, especially at the enantiomer level. In the present study, zebrafish were selected as a typical model for mefentrifluconazole enantiomer exposure. Metabolomic and transcription analyses were performed with 0.01 and 0.10 mg/L mefentrifluconazole and its enantiomers (i.e., rac-mfz/(-)-mfz/(+)-mfz) at 28 days. The ¹H nuclear magnetic resonance (NMR)-based metabolomics analysis showed that 9, 10 and 4 metabolites were changed significantly in the rac-mfz, (+)-mfz and (-)-mfz treatment groups compared with the control group, respectively. The differential metabolites were related to energy metabolism, lipid metabolism and amino acid metabolism. The qRT-PCR analysis revealed that the expression of lipid metabolism-, apoptosis- and CYP-related genes in the livers of female zebrafish in rac-mfz and (+)-mfz was 1.61-108.92 times and 2.37-551.34 times higher than that in (-)-mfz, respectively. The results above indicate that exposure to mefentrifluconazole induced enantioselective liver toxicity in zebrafish. Our study underlined the importance of distinguishing different enantiomers, which will contribute to environmental protection.

Enantioselective monitoring chiral fungicide mefentrifluconazole in tomato, cucumber, pepper and its pickled products by supercritical fluid chromatography tandem mass spectrometry

A fast, effective, and environmental-friendly method was developed for enantioseparation and analysis of mefentrifluconazole in vegetables based on supercritical fluid chromatography tandem mass spectrometry. The enantioselective behaviors of mefentrifluconazole enantiomers in tomato, cucumber, and pepper in the greenhouse, and pickled cucumber and pepper during processing were investigated. Mefentrifluconazole enantiomers could obtain baseline separation within 2 min. The average recoveries of all matrices ranged from 78.4% to 119.0%, with relative standard deviations less than 16.8% for two enantiomers. S-(+)-mefentrifluconazole was preferentially degraded in pepper, while there was no enantioselectivity in tomato and cucumber under field conditions. During processing, S-(+)-mefentrifluconazole was reduced preferentially than R-(-)-mefentrifluconazole in pickled cucumber and cucumber brine. Inversely, R-(-)-mefentrifluconazole degraded faster than S-(+)-mefentrifluconazole in pepper brine. But, no obvious enantioselectivity was observed in pickled pepper. The result of this study could contribute to a more accurate dietary risk assessment of mefentrifluconazole in vegetables and processed products.

Enantiomeric profiling of mefentrifluconazole in watermelon across China: Enantiochemistry, environmental fate, storage stability, and comparative dietary risk assessment

Elucidating the enantiomeric chemistry and enantioselective fate of the novel chiral triazole fungicide mefentrifluconazole is of vital importance for agroecosystem safety and human health. The absolute configuration of mefentrifluconazole was identified firstly as S-(+)-mefentrifluconazole and R-(-)-mefentrifluconazole on a cellulose tris(3-chloro-4-methylphenylcarbamate) chiral phase. A baseline resolution (Rs, 2.51), favorable retention (RT ≤ 2.24 min), and high sensitivity (LOQ, 0.5 μg/kg) of enantiomer pair were achieved by reversed-phase liquid chromatography tandem mass spectrometry combined with a 3D response surface strategy. Nationwide field trials were undertaken to clarify the enantiomer occurrence, enantioselective dissipation, terminal concentrations, and storage stability of S-mefentrifluconazole and R-mefentrifluconazole in watermelon across China. The original deposition of the sum of enantiomer pair was estimated to be 14.4-163.7 μg/kg, and terminally decreased to < LOQ-59.3 μg/kg 10 days after foliage application. S-mefentrifluconazole preferentially degraded (T_1/2, 3.3-6.0 days), resulting in the relative enrichment of R-mefentrifluconazole (T_1/2, 3.9-6.6 days) in watermelon. A probabilistic model is recommended for the dietary risk assessment, although both acute (%ARfD, 0.435-22.188%) and chronic (%ADI, 1.697-9.658%) risks are acceptable for associated population. The long-term exposures should be continuously emphasized given the increasing applications and persistent fate of mefentrifluconazole, especially for urban children.

Enantioselective determination of phenthoate enantiomers in plant-origin matrices using reversed-phase high-performance liquid chromatography-tandem mass spectrometry

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.

Absolute Configuration, Enantioselective Bioactivity, and Degradation of the Novel Chiral Triazole Fungicide Mefentrifluconazole

Mefentrifluconazole is a new chiral triazole fungicide with a pair of enantiomers. However, the enantioselective differences in the biological effects and environmental behaviors of mefentrifluconazole are unclear. In the present work, a new simultaneous determination method of mefentrifluconazole enantiomers was established using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The absolute configuration of the two mefentrifluconazole enantiomers was confirmed by comparing the experimental and calculated ECD spectra. The enantioselective bioactivity to target fungi and degradation in cucumber samples were also assessed. The absolute configurations of the two enantiomers eluted on the Superchiral IG-3 column were confirmed as R-(-)-mefentrifluconazole and S-(+)-mefentrifluconazole. The R-(-)-mefentrifluconazole possessed 5-473 times higher bioactivity than S-(+)-mefentrifluconazole toward six kinds of target pathogenic fungi. In addition, R-(-)-mefentrifluconazole exhibited stronger efficacy of suppression of ergosterol biosynthesis. The molecular docking results indicated that R-(-)-mefentrifluconazole had shorter binding distances and lower energies with the target protein than S-(+)-mefentrifluconazole, which may result in the enantioselective bioactivity. The high-efficiency enantiomer of R-(-)-mefentrifluconazole has longer duration in cucumber samples due to the relatively long half-life of 4.0 days. This research has clarified the bioactivity differences and mechanism between mefentrifluconazole enantiomers against target fungi and laid the foundation for an in-depth study of mefentrifluconazole at the chiral level.

Development of a colorimetric sensor array based on monometallic and bimetallic nanoparticles for discrimination of triazole fungicides

Due to the widespread use of pesticides and their harmful effects on humans and wildlife, monitoring their residual amounts in crops is critically essential but still challenging regarding the development of high-throughput approaches. Herein, a colorimetric sensor array has been proposed for discrimination and identification of triazole fungicides using monometallic and bimetallic silver and gold nanoparticles. Aggregation-induced behavior of AgNPs, AuNPs, and Au-AgNPs in the presence of four triazole fungicides produced a fingerprint response pattern for each analyte. Innovative changes to the metal composition of nanoparticles leads to the production of entirely distinct response patterns that can be used for the detection and discrimination of triazoles. Pattern recognition methods, including linear discriminant analysis (LDA) and hierarchical cluster analysis, have been employed for the differentiation of triazoles in the concentration range of 0.1-0.55 μg mL^-1. Besides, the sensor array demonstrates promising practicability to satisfactorily distinguished triazole in mixtures and complex media of wheat flour and cucumber samples. The proposed colorimetric sensor array might pave the way towards a cost-effective and rapid, yet sensitive platform for high-throughput monitoring of residual amounts of pesticides for on-site applications.

HLB-MCX-Based Solid-Phase Extraction Combined with Liquid Chromatography-Tandem Mass Spectrometry for the Simultaneous Determination of Four Agricultural Antibiotics (Kasugamycin, Validamycin A, Ningnanmycin, and Polyoxin B) Residues in Plant-Origin Foods

An ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was established for the determination of four highly polar agricultural antibiotics kasugamycin, validamycin A, ningnanmycin, and polyoxin B in plant-derived foods. The samples were extracted with a 0.2% formic acid solution, purified by hydrophilic-lipophilic balance and mixed-mode cation-exchange solid-phase extraction, and then reconstituted for UPLC-MS/MS detection. The chromatographic analysis was performed on a BEH Amide column (100 mm × 2.1 mm, 1.7 μm) using gradient elution with a 0.1% formic acid solution and 0.1% formic acid acetonitrile as mobile phases. Method validation was performed on 15 matrices spiked at 0.02 (or 0.05), 0.5, and 2 mg/kg. The mean recovery rate ranged from 75 to 102% with relative standard deviations (RSD) was less than 20%. Good linearities (r > 0.99) in the range of 0.002-0.2 μg/mL were obtained. The limits of quantification (LOQs) were 0.02 and 0.05 mg/kg. Studies on the stability of the analytes in the stored kiwifruit samples showed that kasugamycin, validamycin A, and ningnanmycin were stable for at least 6 months, while polyoxin B was observed to be partially degraded (the degradation rate at 6 months was 31.3%). The method was demonstrated to be effective and reliable in real samples. In the kiwifruit samples treated after 7 days, no residues of ningnanmycin and polyoxin B were detected, while the residues of kasugamycin and validamycin A were 0.12 and 0.038 mg/kg, respectively.