The application of chiral ultra-high-performance liquid chromatography tandem mass spectrometry to the separation of the zoxamide enantiomers and the study of enantioselective degradation process in agricultural plants

Rational understanding of chiral fungicide penthiopyrad stereoselectivity: Bioactivity, aquatic toxicity and cytotoxicity

Penthiopyrad is a novel chiral succinate dehydrogenase inhibitor (SDHI) fungicide with two enantiomers. However, enantioselective information on the biological activity, nontarget organisms and human health risk of penthiopyrad is not comprehensive, which may cause inaccurate risk assessment. In this study, the enantioselective bioactivity to three kinds of phytopathogens (Rhizoctonia solani, Botrytis cinerea and Sclerotinia sclerotiorum) was first disclosed, and the antifungal activity of S-(+)-penthiopyrad was higher than that of R-(-)-penthiopyrad by 12-37 times. Moreover, its enantioselective toxicity to Raphidocelis subcapitata and Daphnia magna was also clarified, and the order of toxicity was S-(+)-penthiopyrad > rac-penthiopyrad >R-(-)-penthiopyrad, with 1.8- and 5.3-fold differences between the two enantiomers. Furthermore, the enantioselectivity of penthiopyrad on HepG2 cytotoxicity was studied. The data showed that the cytotoxicity of S-(+)-penthiopyrad was 1.8 times higher than that of R-(-)-penthiopyrad, and S-(+)-penthiopyrad had a stronger impact on cell proliferation, oxidative stress and lipid peroxidation. In summary, due to the enantioselectivity of the activity and toxicity of the chiral pesticide, the efficacy and risk evaluation of penthiopyrad should be considered at the enantiomer level.

Co-existing antibiotics alter the enantioselective dissipation characteristics of zoxamide and drive combined impact on soil microenvironment

Co-existence of antibiotics (ABX) in soil may expand the environmental harm of pesticide pollution. Our study investigated the combined effects of five antibiotics chlortetracycline (CTC), oxytetracycline (OTC), tetracycline (TC), sulfamethoxazole (SMX), enrofloxacin (ENR) on enantioselective fate of zoxamide (ZXM) and soil health. The results showed that S-(+)-ZXM preferentially dissipated in soil. ABX prolonged dissipation half-life and reduced enantioselectivity of ZXM. Soil was detected to be more acidic after long-term treatment of ZXM and ABX. Lowest soil available N, P, K were found in ZXM + SMX, ZXM + OTC and ZXM + SMX groups at 80 days, respectively. ABX had demonstrated effective promotion of catalase (S-CAT), urease (S-UE) and negative impact on dehydrogenase (S-DHA), sucrase (S-SC) activities. Bacteria Lysobacter, Sphingomonas and fungus Mortierella were identified as the most dominant genera, which possessed as potential microbial resources for removal of composite pollution from ZXM and ABX. SMX and TC, SMX, ENR, respectively, contributed to the alteration of bacteria and fungi community abundance. Soil acidity, available N and enzyme activity showed stronger correlations with bacteria and fungi compared to other environmental factors. Our findings highlighted the interactions between ZXM and ABX from the perspective of soil microenvironment changes. Moreover, a theoretical basis for the mechanism was actively provided.

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.

Lateral flow immunoassay based on gold nanoparticles for rapid and sensitive detection of zoxamide in grape, tomato and cucumber samples

In the study, we discovered zoxamide hapten (ZOX-hapten) by introducing a carboxyl extension chain, combined it with protein to make a complete antigen to immunize mice, and generated a monoclonal antibody (mAb) against ZOX. To identify ZOX residues in grape, tomato, and cucumber samples, we used our anti-ZOX mAb to develop a lateral flow immunoassay (LFIA) strip. In grape, tomato, and cucumber samples, the calculated detection limit of the LFIA strip in grape, tomato and cucumber samples was 3.44, 4.78 and 3.53 ng/g, respectively. Using the LFIA strip, the recovery rate from grape samples was 96.4-106.8%, and that from tomato samples was 98.4-107.5%, while the recovery from cucumber samples was 99.4-111.3%. These results showed that our LFIA strip could be expected to achieve rapid screening of ZOX residues in fruits and vegetables.

Systematic evaluation of chiral fungicide penflufen for the bioactivity improvement and input reduction using alphafold2 models and transcriptome sequencing

Traditional risk assessment of pesticide concludes at the racemic level, which is often incomprehensive. In this study, systematic studies on environmental stability, bioactivity, and ecotoxicological effects of fungicide penflufen were carried out at the enantiomeric level. The single-enantiomer of penflufen was successfully separated and prepared, and their stability was verified in different environmental matrices. Meanwhile, bioactivity test indicated that S-(+)-penflufen had increased bioactivity with its bioactivities against Rhizoctonia solani, Fusarium oxysporum, and Fusarium moniliforme being factors of 7.8, 1.8, and 4.7, respectively greater than those of R-(-)-penflufen. Molecular docking results showed the strong hydrogen bond interactions with Leu300, enantiomer-specific hydrophobic interactions with Cys299, Arg91, and His93, and the greater binding energy between S-(+)-penflufen and succinate dehydrogenase of Rhizoctonia solani caused the selective bioactivity. Additionally, two enantiomers showed low acute toxicity whereas selective sub-chronic toxicity to earthworms. In sub-chronic toxicity test, the accumulated enantiomers caused abnormalities in intestinal tract structure, enzyme activities, and gene expression of earthworms, especially in the S-(+)-penflufen treatment. The selective interactions between penflufen enantiomers and key proteins were elucidated using molecular docking, which may be the main reason of stereoselective subchronic toxicity. S-(+)-penflufen has high bioactivity and low acute risk, it has great potential for development.

Assessment of the eco-toxicological effects in zoxamide polluted soil amended with fertilizers-An indoor evaluation

Zoxamide is a benzamide fungicide applied to control diseases caused by oomycete fungi. Fertilizers are important agricultural supplies to adjust soil properties and increase nutrition. To investigate the impact of zoxamide and seven fertilizers urea, phosphate fertilizer, potash fertilizer, compound fertilizer, organic fertilizer, vermicompost and soya bean cakes on the soil environment, the enantioselective dissipation characteristics of zoxamide, soil enzyme activities, pH and N, P nutrition changes were comprehensively analyzed in our present study. The enantioseparation method was successfully validated to quantify the zoxamide enantiomers in soil by HPLC using Chiral NQ (2)-RH column. Our results demonstrated that the R-(-)- and S-(+)-zoxamide half dissipated in the range of 10.88-17.81 and 8.05-14.41 days, respectively. S-(+)-zoxamide disappeared faster in soil. The vermicompost accelerated the dissipation rate of S-(+)-zoxamide, while urea, phosphate, organic and vermicompost fertilizer increased the dissipation selectivity. Zoxamide and fertilizers other than urea caused soil acidification during 80 days. Zoxamide was beneficial to soil catalase, instead inhibited soil urease, dehydrogenase activities and available phosphorus content. No significant effects on sucrase activity and available nitrogen content were found by zoxamide. Vermicompost and soya bean cakes had lasting and outstanding performance in efficiently improving soil enzyme activity and N, P nutrition. The comprehensive understanding of the ecological impact induced by chiral pesticide enantiomers and fertilizers on soil is vital to ensure the sustainable development and safety of agricultural production.

Enantioseparation and dissipation of acephate and its highly toxic metabolite methamidophos in pakchoi by supercritical fluid chromatography tandem mass spectrometry

Acephate is widely used in crops as racemate. However, the enantioselective dissipation of acephate enantiomers has not been investigated in pakchoi. A sensitive and effective approach was established for determining residues of acephate and its highly toxic metabolite methamidophos enantiomers by supercritical fluid chromatography tandem mass spectrometry. Baseline separations for their enantiomers were achieved by using a Chiralcel OD-H column. The optimal chromatographic conditions were obtained as follows: CO₂ /ethanol (95/5) as mobile phase; flow rate, 3.0 mL/min; column temperature, 40°C. The mean recoveries (RSDs) of analytes were in the range of 77%-83.1% (6.1%-9.9%), 75.4%-87.5% (9.3%-13.2%), and 81.5%-84.2% (7.1%-13.4%) at three fortification levels (0.005, 0.05, and 0.5 mg/kg for each enantiomer) for interday assay (n = 18). The method was used to evaluate the enantioselective dissipation of acephate and methamidophos in pakchoi. S-acephate dissipated faster than R-acephate, while the concentration of R-methamidophos was higher than that of S-methamidophos during the entire study period. The results indicated that the R-enantiomer of acephate and methamidophos was preferentially enriched in pakchoi. The established analysis approach and the study data provided useful information for the rational use of acephate in agriculture. This article is protected by copyright. All rights reserved.

Enantioselective Dissipation, Residue, and Risk Assessment of Diniconazole Enantiomers in Four Kinds of Fruits

Chiral diniconazole is a widely used triazole fungicide, while its enantioselective behaviors in fruits have not been reported. In this article, the absolute configuration was confirmed. A fast supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS) method was developed for the chiral separation and enantioselective study of diniconazole in four kinds of fruits. The residual concentrations gradually decreased with time in four kinds of fruits after applying diniconazole. The dissipation half-lives of R-diniconazole and S-diniconazole were in the range of 5.3-7.9 and 2.5-7.1 days respectively, and S-diniconazole was degraded preferentially. The residue concentrations were lower than the EU's MRL (0.01 mg/kg) on the 40th (harvest time), 30th, and 10th day in pear, jujube, and apple, respectively. But, in peach, residue concentrations were still higher than the MRL after 60 days and the ratio of R/S was 2.2. These results could be helpful for the reasonable use and risk assessment of chiral diniconazole.

Zoxamide accumulation and retention evaluation after nanosuspension technology application in tomato plant

BACKGROUND

Low water solubility of pesticide requires formulations with high levels of stabilizers and organic solvents. Moreover, only 0.1% of the applied pesticides formulation reaches the target, while 99.9% spreads in the surrounding environment. Therefore, there is the need for more efficient and environmentally sustainable alternatives.

RESULTS

Zoxamide (ZO) nanosuspension was prepared through a media milling technique by using the stabilizer polysorbate 80. The thin and acicular crystals obtained, showed particle size of 227 nm, polydispersion index of 0.247 and zeta potential of -28 mV. Dimensional data and morphology of ZO nanocrystals alone, on tomato leaves and berries, were confirmed by scanning electron microscopy. The reduction in size for ZO crystals obtained after the milling process increased pesticide water solubility till 39.6 mg L^-1 , about 1.6 the solubility obtained with a conventional commercial formulation. Field and dip contamination trials performed on tomato plants showed the nanosuspension's ability to increase ZO deposition and accumulation versus a coarse ZO suspension and commercial formulation, respectively.

CONCLUSIONS

The nanoformulation proposed, resulted in low cost and was easy to make. Moreover, the organic solvent-free composition together with a low surfactant addition assured a minor environmental impact. Finally, the increased retention and deposition of the fungicide can reduce the amounts of ZO formulation applied to tomatoes. © 2021 Society of Chemical Industry.

Analytical research on the separation and residue of chiral pesticide triadimenol in fruit and vegetable puree

In this paper, a method for the separation of triadimenol stereoisomers using ultra-performance convergence chromatography and an analytical method for the determination of triadimenol stereoisomer residues in pumpkin puree, apple puree, and tomato puree as a supplement for infants are established. Test samples were extracted with acetonitrile and successively purified with graphitized carbon black and Florisil column. Afterward, Acquity Trefoil AMY1 column was adopted for chiral separation of chromatographic column, and gradient elute was carried out with supercritical carbon dioxide-methanol as the mobile phase and with external standard method for quantitation. Results showed that the linearly dependent coefficient of the four kinds of triadimenol stereoisomers within 1.0 and 50 mg/L was greater than 0.9997, and the limit of quantitation of the four kinds of triadimenol stereoisomers was 0.05 mg/kg. Recovery experiment was carried out within 0.05 and 1.0 mg/kg scope, the recoveries were 81.0-107％, and the relative standard deviation was 2.3-7.6%. This method implemented the separation of triadimenol stereoisomers and its residue test in pumpkin puree, apple puree, and tomato puree as a supplement for infants, and it can provide reliable technical support for the analysis of pesticide residue and assessment of product quality.

Novel tapered variable diameter biological fluidized bed for treating pesticide wastewater with high nitrogen removal efficiency and a small footprint

In this study, the removal efficiency of nitrogen, specific nitrification rate (SNR), specific denitrification rate (SDNR) and compliance rate of the novel tapered variable diameter biological fluidized bed (TVDBFB) and anoxic/oxic (AO) process were compared at different temperatures. The results showed that the optimal TN, NH₄⁺-N, and TKN removal efficiencies of the TVDBFB were 76%, 89% and 88%, respectively, and those of AO were 65%, 67% and 69%, respectively. The SNR and SDNR of the TVDBFB were significantly higher than those of AO. The TVDBFB had a smaller footprint than AO. The alkalinity/NH₄⁺-N, BOD₅/TN and temperature play important roles in the compliance rate. Increasing the carrier packing rate has emerged as a new strategy for enhancing the compliance rate. Mathematical models were developed and determined to be well-fitted with the experimental values, which can be employed to predict the SNR and SDNR of the TVDBFB.

Enantioselective Detection, Bioactivity, and Degradation of the Novel Chiral Fungicide Oxathiapiprolin

Oxathiapiprolin is a novel chiral piperidine thiazole isooxazoline fungicide that contains a pair of enantiomers. An effective analytical method was established for the enantioselective detection of oxathiapiprolin in fruit, vegetable, and soil samples using ultraperformance liquid chromatography-tandem triple quadrupole mass spectrometry. The optimal enantioseparation was achieved on a Chiralpak IG column at 35 °C using acetonitrile and 0.1% formic acid aqueous solution (90:10, v/v) as the mobile phase. The absolute configuration of the oxathiapiprolin enantiomers was identified with the elution order of R-(-)-oxathiapiprolin and S-(+)-oxathiapiprolin by electron circular dichroism spectra. The bioactivity of R-(-)-oxathiapiprolin was 2.49 to 13.30-fold higher than that of S-(+)-oxathiapiprolin against six kinds of oomycetes. The molecular docking result illuminated the mechanism of enantioselectivity in bioactivity. The glide score (-8.00 kcal/mol) for the R-enantiomer was better with the binding site in Phytophthora capsici than the S-enantiomer (-7.50 kcal/mol). Enantioselective degradation in tomato and pepper under the field condition was investigated and indicated that R-(-)-oxathiapiprolin was preferentially degraded. The present study determines the enantioselectivity of oxathiapiprolin about enantioselective detection, bioactivity, and degradation for the first time. The R-enantiomer will be a better choice than racemic oxathiapiprolin to enhance the bioactivity and reduce the pesticide residues at a lower application rate.

Chiral chromatography method screening strategies: Past, present and future

Method screening is an integral part of chromatographic method development for the separation of racemates. Due to the highly complex retention mechanism of a chiral stationary-phase, it is often difficult, if not impossible, to device predefined method-development steps that can be successfully applied to a wide group of molecules. The standard approach is to evaluate or screen a series of stationary and mobile-phase combinations to increase the chances of detecting a suitable separation condition. Such a process is often the rate-limiting step for high-throughput analyses and purification workflows. To address the problem, several solutions and strategies have been proposed over the years for reduction of net method-screening time. Some of the strategies have been adopted in practice while others remained confined in the literature. The main objective of this review is to revisit, critically discuss and compile the solutions published over the last two decades. We expect that making the diverse set of solutions available in a single document will help assessing the adequacy of existing screening protocols in laboratories conducting chiral separation.

Effective Remediation Strategy for Xenobiotic Zoxamide by Pure Bacterial Strains, Escherichia coli, Streptococcus pyogenes, and Streptococcus pneumoniae

Zoxamide, a class IV hazardous fungicide, is perilous for the environment due to its highly persistent nature. Up till the current date, there are no reports on the biodegradation of zoxamide. The scarcity of knowledge in this domain led to the present research to evaluate the biodegradation of this benzamide fungicide by three bacterial strains, Escherichia coli (EC), Streptococcus pyogenes (SPy), and Streptococcus pneumoniae (SP). Biotransformation of zoxamide was scrutinized in nutrient broth assemblies for a period of 28 days followed by UV-visible spectrophotometer and GC-MS analysis of the metabolites. The results exhibited a low to medium biodegradation potential of the bacterial cells to metabolize zoxamide. The highest biotransformation percentage was observed by E. coli to be 29.8%. The order of half-life calculated for the degradation results was EC (42.5) < SPy (58.7) < SP (67.9) days. GC-MS analysis indicated the formation of several metabolites including, 2-(3,5-dichloro-4-methylphenyl)-4-ethyl-4-methyl-4H-1,3-oxazin-5(6H)-one, 3,5-dichloro-N-(3-hydroxy-1-ethyl-1-methyl--2-oxopropyl)-4-methylbenzamide and 3,5-dichloro-4-methylbenzamide. The research could influence the biotreatment strategies for the environmentally friendly eradication of xenobiotics.

Mechanisms of Increased Indoxacarb Toxicity in Methoxyfenozide-Resistant Cotton Bollworm Helicoverpa armigera (Lepidoptera: Noctuidae)

Indoxacarb is an important insecticide for the selective control of Helicoverpa armigera. It can be bioactivated to the more effective N-decarbomethoxylated indoxacarb (DCJW) by esterases in pests. It was observed that both field and laboratory selected populations of H. armigera showed negative cross-resistance between indoxacarb and methoxyfenozide. The Handan population exhibited moderate resistance to indoxacarb, but was susceptible to methoxyfenozide; the Baoding and Yishui populations exhibited moderate resistance to methoxyfenozide, but they were susceptible to indoxacarb. Moreover, the toxicity of indoxacarb was enhanced 1.83-fold in the laboratory methoxyfenozide-resistant H. armigera, and susceptibility to methoxyfenozide was increased 2.81-fold in the laboratory indoxacarb-resistant H. armigera. In vivo, DCJW concentrations in the susceptible and methoxyfenozide-selected (laboratory methoxyfenozide-resistant) populations were 4.59- and 4.31-fold greater than in the indoxacarb-resistant Handan population 1 h after dosing. After 2 h, the highest concentrations of DCJW and indoxacarb appeared in the methoxyfenozide-selected population. Meanwhile, increased carboxyl esterase (CarE) and decreased glutathione S-transferase (GST) activities were observed in the methoxyfenozide-selected population. However, the indoxacarb-selected (laboratory indoxacarb-resistant) and Handan populations showed a higher disappearance of indoxacarb and DCJW, and the activity of cytochrome P450 mono-oxygenase in these populations were significantly increased. This study showed that the improved toxicity of indoxacarb, as observed in the methoxyfenozide-selected H. armigera, was correlated with increased CarE activity, decreased GST activity, and the in vivo accumulation of indoxacarb and DCJW. The significantly increased cytochrome P450 activity and higher disappearance of indoxacarb and DCJW in indoxacarb-resistant H. armigera resulted in the decreased toxicity of indoxacarb.

A systematic evaluation of zoxamide at enantiomeric level

Zoxamide is a recently discovered chiral fungicide that applied to agricultural production, but the potential environmental risk may be underestimated because the risk posed by either enantiomer has not been adequately assessed. Therefore, systemic evaluation of zoxamide was first carried out at the enantiomeric level. Enantioselective bioactivity against target pathogens (Phytophthora capsici Leonian, Alternaria solani, Botryis cinerea, Colletotrichum gloeosprioides Penz, Phytophthora sojae Kaufmann & Gerdemann) was explored, and the order of the bioactivity was R-zoxamide >Rac-zoxamide >S-zoxamide, with a 9.9- to 140.0-times difference between two enantiomers. Molecular docking simulation was utilized to clarify the mechanism underlying the observed differences in enantioselective bioactivity, and the result indicated that a difference of Van der waals force between R/S-zoxamide and the specific receptor gave rise to the different antifungal activity. The enantioselective toxicity result demonstrated that R-zoxamide had 4.9- to 10.8- times greater acute toxicity to Selenastrum capricornutum and Daphnia magna than S-zoxamide. S-zoxamide degraded faster under aerobic condition in all three types of soils, giving rise to an enrichment of high-risk R-enantiomer. Under anaerobic condition, however, no significant difference in dissipation rate was observed between two enantiomers. R-zoxamide was 1.5- to 3.5-times more bioactive and 1.1- to 1.5-times more toxic than Rac-zoxamide, which means developing R-zoxamide instead of racemate is a potential way to reduce pesticide dosage without loss of efficacy against target organisms and that an inactive isomer would no more be released to the environment. This study may have implications for better practical application and environmental risk assessment of zoxamide enantiomers.

Development of S-Fluxametamide for Bioactivity Improvement and Risk Reduction: Systemic Evaluation of the Novel Insecticide Fluxametamide at the Enantiomeric Level

Increasing numbers of novel pesticides have been applied in agriculture. However, traditional evaluation of pesticides does not distinguish between their enantiomers, which may lead to inaccurate results. In this study, systematic research on the chiral insecticide fluxametamide was conducted at the enantiomeric level. The methods for enantioseparation and semipreparative separation of fluxametamide enantiomers were developed. The optical rotation and absolute configuration of two enantiomers were determined, and their stability was verified in solvents and soils. Enantioselective bioactivities against four target pests (Plutella xylostella, Spodoptera exigua, Aphis gossypii, and Tetranychus cinnabarinus) were tested. Acute toxicities of fluxametamide enantiomers toward honeybees were also evaluated. S-(+)-Isomer exhibited 52.1-304.4 times and 2.5-3.7 times higher bioactivity than R-(-)-isomer and rac-fluxametamide, respectively. Meanwhile, rac-fluxametamide was more toxic than S/R-isomer, and S-(+)-isomer showed >30-fold higher acute toxicity than R-(-)-isomer. Molecular docking studies were performed with γ-aminobutyric acid receptor (GABAR) to monitor the mechanism of stereoselective bioactivity. The better Grid score of S-(+)-fluxametamide (-60.12 kcal/mol) than R-(-)-enantiomer (-56.59 kcal/mol) indicated higher bioactivity of S-(+)-isomer than of R-(-)-isomer. The dissipation of fluxametamide in cabbage, Chinese cabbage, and soil was nonenantioselective under field conditions. Development of S-(+)-fluxametamide could maintain the high-efficacy and low-risk properties, which should attract attention of producers, applicators, and managers of pesticides.

Ultra-high performance liquid chromatography-MS/MS (UHPLC-MS/MS) in practice: analysis of drugs and pharmaceutical formulations

Background

UHPLC-MS/MS is connected in various research facilities for the qualitative and quantitative investigation of a pharmaceutical substance, pharmaceutical items, and biological specimen.

Main body

The commence review article is an endeavor to offer pervasive awareness around assorted aspects and details about the UHPLC-MS/MS and related techniques with the aim on practice to an estimation of medicinal active agents in the last 10 years. The article also focused on isolation, separation, and characterization of present impurity in drug and biological samples.

Conclusion

Review article compiles a general overview of medicinally important drugs and their analysis with UHPLC-MS/MS. It gives fundamental thought regarding applications of UHPLC-MS/MS for the study on safety limit. The summary of developed UHPLC-MS/MS methods gives a contribution to the future trend and limitations in this area of research.

Enantioselective Separation and Dissipation of Prothioconazole and Its Major Metabolite Prothioconazole-desthio Enantiomers in Tomato, Cucumber, and Pepper

In this study, a simple and effective chiral analytical method was developed to monitor prothioconazole and prothioconazole-desthio at the enantiomeric level using supercritical fluid chromatography-tandem triple quadrupole mass spectrometry. The baseline enantioseparation for prothioconazole and prothioconazole-desthio was achieved within 2 min on a Chiralcel OD-3 column with CO₂/0.2% acetic acid-5 mmol/L ammonium acetate 2-propanol (85:15, v/v) as the mobile phase at a flow rate of 1.5 mL/min and column temperature of 25 °C. The limit of quantitation for each enantiomer was 5 μg/kg, with a baseline resolution of >3.0. The results of enantioselective dissipation showed that R-(-)-prothioconazole was preferentially degraded in tomato, cucumber, and pepper under greenhouse conditions. S-(-)-prothioconazole-desthio was preferentially degraded in tomato and cucumber; however, R-(+)-prothioconazole-desthio was preferentially degraded in pepper. Results of this study may help to facilitate more accurate risk assessment of prothioconazole and its major metabolite in agricultural products.

Analysis of Enantiomers in Products of Food Interest

The separation of enantiomers has been started in the past and continues to be a topic of great interest in various fields of research, mainly because these compounds could be involved in biological processes such as, for example, those related to human health. Great attention has been devoted to studies for the analysis of enantiomers present in food products in order to assess authenticity and safety. The separation of these compounds can be carried out utilizing analytical techniques such as gas chromatography, high-performance liquid chromatography, supercritical fluid chromatography, and other methods. The separation is performed mainly employing chromatographic columns containing particles modified with chiral selectors (CS). Among the CS used, modified polysaccharides, glycopeptide antibiotics, and cyclodextrins are currently applied.

Stereoselective degradation behaviour of carfentrazone-ethyl and its metabolite carfentrazone in soils

The stereoselective environmental behaviour of carfentrazone-ethyl and its metabolite carfentrazone enantiomer in three types of soil were studied under aerobic conditions. Under aerobic conditions, significant stereoselective difference in the degradation behaviour of carfentrazone-ethyl and its metabolite carfentrazone enantiomer was observed in Jiangxi red soil, Jilin black soil and Anhui paddy soil. The EF values of the carfentrazone-ethyl enantiomers in Anhui paddy soil, Jilin black soil, and Jiangxi red soil were 0.67, 0.65 and 0.57, respectively. The EF values of the carfentrazone enantiomer in the three types of soil were 0.75, 0.80 and 0.76. No bidirectional chiral inversion of enantiopure carfentrazone-ethyl and carfentrazone enantiomers was observed in Jilin soil. As a result, R-(+)-carfentrazone-ethyl and S-(+)-carfentrazone in soil would be preferentially degraded, while S-(-)-carfentrazone-ethyl and R-(-)-carfentrazone were enriched. The results found in this paper could provide more scientific guidance for the risk assessments of carfentrazone-ethyl from a chiral perspective.