Simultaneous enantioselective determination of 22 chiral pesticides in fruits and vegetables using chiral liquid chromatography coupled with tandem mass spectrometry

Green synthesis of superhydrophilic resin/graphene oxide for efficient analysis of multiple pesticide residues in fruits and vegetables

The escalating use of pesticides on fruits and vegetables has raised concerns about potential health risks. Therefore, we developed a superhydrophilic resin/graphene oxide (SR/GO) with rich adsorption interactions using an eco-friendly synthetic approach. SR/GO demonstrated excellent hydrophilicity, ensuring optimal contact with aqueous sample matrices. The multiple adsorption interactions, including π-π conjugation, hydrogen bonding, and electrostatic adsorption, facilitated multi-pesticide residue co-extraction. The synthesized SR/GO was applied to a miniaturized centrifugation-accelerated pipette-tip extraction method, coupled with high-performance liquid chromatography. The optimized method exhibited low consumption (15.0 mg adsorbent), and high efficiency, with low detection limits (1.4-2.9 ng g-1) and high recoveries (75.3-113.0%). Water-compatible SR/GO, along with a miniaturized extraction process, showcases a potent analytical approach for pesticide residue analysis in fruits and vegetables. The significance of this method lies in its ability to ensure agricultural and food safety by using a low-cost and efficient multi-pesticide residue analytical strategy.

Development of aptasensor for chlorpyrifos detection using paper-based screen-printed electrode

Novel Carbon quantum dots-graphite composite ink-based Screen-printed electrodes (CQDs/SPEs) were used to assemble a highly sensitive electrochemical aptasensor against chlorpyrifos (CPF). The aptasensor showed a broad linear range from 1 pM (0.445 ng/ml) to 500 nM (0.22 mg/ml) with a detection limit (LOD) 0.834 pM (0.37 ng/ml); sensitivity 21.39 μA pM-1 cm- 2 and with good linearity of R2 = 0.973. Moreover, the aptasensor's showed better selectivity among few other pesticides. Further, the aptasensor electrode showed high stability for five months when stored at 4 °C. In the final step, the aptasensor's ability to identify CPF in real samples was evaluated on spiked potato (Solanum tuberosum) extract samples. Potato extract spiked with CPF in the electrochemical aptasensing platform showed excellent linearity of R2 = 0.981. The developed aptasensor showed good response to without spiked potato extract with increasing volumes. Hence, the developed aptasensor demonstrated reasonable applicability in real food and agriculture samples.

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.

Eating with peel or not: Investigation of the peel consumption situation and its nutrition, risk analysis, and dietary advice in China

Nutritious, balanced, tasty and easy to eat, fruit is an indispensable health food for consumers. With consumers' increasing respect for the concept of health, green and nutrition, the peel, which has higher nutritional value compared to the pulp, is gradually being emphasized in the consumption process. The suitability of fruit peels for consumption is influenced by various factors, such as the amount of pesticide residues, nutrient content, ease of peeling, and fruit texture, but there is a lack of relevant studies to guide consumers' scientific intake of fruit peels. This review first investigated chineses consumers consumption of common fruits with peels, especially eight fruits that are controversial in terms of whether to consume them with peels, and the results showed that whether people consume peels depends mainly on their nutritional value and pesticide residues. Based on this, the paper discusses the common methods of pesticide detection and removal from fruit peels, as well as the nutrients contained in different fruit peels and their physiological activities, if the peels usually have stronger antioxidant, anti-inflammatory and anti-tumor activities than the pulp. Finally, reasonable dietary recommendations are made on whether fruits should be consumed with their peels, with a view to guiding chineses consumers towards scientific consumption and provide theoretical basis for relevant research in other countries.

Dual-ratiometric aptasensor for simultaneous detection of malathion and profenofos based on hairpin tetrahedral DNA nanostructures

Due to the diversification and complexity of organophosphorus pesticide residues brings great challenges to the detection work. Therefore, we developed a dual-ratiometric electrochemical aptasensor that could detect malathion (MAL) and profenofos (PRO) simultaneously. In this study, metal ions, hairpin-tetrahedral DNA nanostructures (HP-TDN) and nanocomposites were used as signal tracers, sensing framework and signal amplification strategy respectively to develop the aptasensor. Thionine (Thi) labeled HP-TDN (HP-TDNThi) provided specific binding sites for assembling Pb2+ labeled MAL aptamer (Pb2+-APT1) and Cd2+ labeled PRO aptamer (Cd2+-APT2). When the target pesticides were present, Pb2+-APT1 and Cd2+-APT2 were dissociated from the hairpin complementary strand of HP-TDNThi, resulting in reduced oxidation currents of Pb²⁺ (I_Pb²⁺) and Cd²⁺ (I_Cd²⁺), respectively, while the oxidation currents of Thi (I_Thi) remained unchanged. Thus, I_Pb²⁺/I_Thi and I_Cd²⁺/I_Thi oxidation current ratios were used to quantify MAL and PRO, respectively. In addition, the gold nanoparticles (AuNPs) encapsulated in the zeolitic imidazolate framework (ZIF-8) nanocomposites (Au@ZIF-8) greatly increased the catch of HP-TDN, thereby amplifying the detection signal. The rigid three-dimensional structure of HP-TDN could reduce the steric hindrance effect on the electrode surface, which could greatly improve the recognition efficiency of the aptasensor for the pesticide. Under the optimal conditions, the detection limits of the HP-TDN aptasensor for MAL and PRO were 4.3 pg mL-1 and 13.3 pg mL-1, respectively. Our work proposed a new approach to fabricating a high-performance aptasensor for simultaneous detection of multiple organophosphorus pesticides, opening a new avenue for the development of simultaneous detection sensors in the field of food safety and environmental monitoring.

Crystal structure of dichlorido-tetrakis((E)-(RS)-1-(2,4-dichlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pent-1-en-3-ol-κ 1 N)cadmium(II), C60H68O4N12Cl10Cd

C60H68O4N12Cl10Cd, triclinic, P 1 ‾ $\overline{1}$ (no. 2), a = 8.9686(15) Å, b = 13.554(2) Å, c = 15.365(3) Å, α = 92.113(3)°, β = 99.047(3)°, γ = 106.492(3)°, V = 1762.1(5) Å3, Z = 1, Rgt (F) = 0.0436, wRref (F 2) = 0.1130, T = 296(2) K.

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 Effects of Triticonazole on Soil and Human Health

Triticonazole is a fungicide used to control diseases in numerous plants. The commercial product is a racemate containing (R)- and (S)-triticonazole and its residues have been found in vegetables, fruits, and drinking water. This study considered the effects of triticonazole on soil microorganisms and enzymes and human health by taking into account the enantiomeric structure when applicable. An experimental method was applied for assessing the effects of triticonazole on soil microorganisms and enzymes, and the effects of the stereoisomers on soil enzymes and human health were assessed using a computational approach. There were decreases in dehydrogenase and phosphatase activities and an increase in urease activity when barley and wheat seeds treated with various doses of triticonazole were sown in chernozem soil. At least 21 days were necessary for the enzymes to recover the activities. This was consistent with the diminution of the total number of soil microorganisms in the 14 days after sowing. Both stereoisomers were able to bind to human plasma proteins and were potentially inhibitors of human cytochromes, revealing cardiotoxicity and low endocrine disruption potential. As distinct effects, (R)-TTZ caused skin sensitization, carcinogenicity, and respiratory toxicity. There were no significant differences in the interaction energies of the stereoisomers and soil enzymes, but (S)-TTZ exposed higher interaction energies with plasma proteins and human cytochromes.

Incorporating Tenax into the in vitro method to improve the predictive capability of bioaccessibility of triazole fungicides in grape

In vitro bioaccessibility assays have been developed for high-throughput prediction of relative bioavailability (RBA). However, methods to reliably and efficiently assess pesticide residues remain limited, hindering the precise estimation of pesticide exposure risk. The inclusion of a sorption sink material to simulate intestinal sorption could be a promising approach to optimize in vitro bioaccessibility methods. The current study aimed to explore the feasibility of incorporating Tenax into the Rijksinstituut voor Volksgezondheid en Milieu (RIVM) method for accurate evaluation of the bioaccessibility of triazole fungicides. The use of 1.0 g of Tenax enabled the valid trapping of triazole fungicides released from grape, resulting in a significant increase of 23.59-38.51 % in the value of bioaccessibility. A strong in vivo-in vitro correlation was observed between pesticide RBA and bioaccessibility, suggesting that the Tenax-assisted RIVM method is a suitable replacement for time-consuming and laborious in vivo alternatives. In addition, the exposure assessment indicated that the hazard quotients for triazole fungicides in grape may be overestimated by 5.79-27.34 % without considering bioaccessibility based on the Tenax-assisted RIVM method. These results provide further insights into the assessment of bioaccessibility-based human exposure to pesticides as well as dietary exposure and related risk for human health.

Evaluation of chiral triticonazole in three kinds of fruits: enantioseparation, degradation, and dietary risk assessment

The enantioselective behaviors of chiral pesticides would affect the accuracy of risk assessment. This study evaluated the enantioselectivity of chiral triticonazole (a widely used fungicide) in three kinds of fruits. Firstly, the enantioseparation of triticonazole enantiomers was carried out within 1.2 min utilizing CHIRALPAK OJ-3 column with a mixture of CO₂ and methanol (93:7, v/v) using SFC-MS/MS. Secondly, field trials were conducted to clarify the enantioselective degradation and residue of S-( +)-triticonazole and R-(-)-triticonazole in fruits. The initial concentrations of rac-triticonazole were 25.1-93.1 ng/g, and enantioselective degradation was observed in pear, peach, and jujube after 2 h, 10 days, and 3 days, respectively. The degradation of S-( +)-triticonazole was fastest in pear (T_1/2, 2.01 days), while the T_1/2 of R-(-)-triticonazole was 5.02 days. The residue concentrations of rac-triticonazole were less than the MRL set by EU (10 ng/g) on the 3rd and 21st day in pear and peach, respectively, which were lower than 10 ng/g in jujube on the 30th day (no MRL). Finally, we found that the dietary intake risks of rac-triticonazole in fruits were low for 2-7 age, 20-50 age/female, and 20-50 age/male. The current study could provide complimentary references for the rational usage, MRL formulation, and risk assessment of chiral triticonazole.

Stereoselective toxicity mechanism of neonicotinoid dinotefuran in honeybees: New perspective from a spatial metabolomics study

Development of stereoisomeric neonicotinoid pesticides with lower toxicity is key to preventing global population declines of honeybees, whereas little is known about the in situ metabolic regulation of honeybees in response to stereoisomeric pesticides. Herein, we demonstrate an integrated mass spectrometry imaging (MSI) and untargeted metabolomics method to disclose disturbed metabolic expression levels and spatial differentiation in honeybees (Apis cerana) associated with stereoisomeric dinotefuran. This method affords a metabolic network mapping capability regarding a wide range of metabolites involved in multiple metabolic pathways in honeybees. Metabolomics results indicate more metabolic pathways of honeybees can be significantly affected by S-(+)-dinotefuran than R-(-)-dinotefuran, such as tricarboxylic acid (TCA) cycle, glyoxylate and dicarboxylate metabolism, and various amino acid metabolisms. MSI results demonstrate the cross-regulation and spatial differentiation of crucial metabolites involved in the TCA cycle, purine, glycolysis, and amino acid metabolisms within honeybees. Taken together, the integrated MSI and metabolomics results indicated the higher toxicity of S-(+)-dinotefuran arises from metabolic pathway disturbance and its inhibitory role in the energy metabolism, resulting in significantly reduced degradation rates of detoxification mechanisms. From the view of spatial metabolomics, our findings provide novel perspectives for the development and applications of pure chiral agrochemicals.

Chiral resolution of the insecticide fipronil enantiomers and the simultaneous determination of its major transformation products by high-performance liquid chromatography interfaced with mass spectrometry

A high-performance liquid chromatography-mass spectrometry (HPLC-MS) method was developed using a chiral column based on amylose tris(3-chloro-5-methylphenylcarbamate) for analysis of fipronil (a popular insecticidal nerve agent) and the related transformation products. The optimized method reached the goal of the simultaneous and complete separation of the multiple fiproles in a single run, including the chiral separation of fipronil enantiomers, fipronil metabolites, and photoproducts. The efficacy of such a method was demonstrated by its application in analyzing a series of fipronil samples exposed to sunlight conditions. In general terms, our study provided experimental approaches and an efficient analytical tool for monitoring the environmental fate of fipronil as well as its multitransformation products upon its applications either in agricultural or any other areas.

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.

Enantioselective bioaccumulation and detoxification mechanisms of earthworms (Eisenia fetida) exposed to mandipropamid

As a novel chiral amide fungicide, the enantioselective behaviors of mandipropamid in the soil environment are unclear. Furthermore, there is a need to understand the stress response mechanisms of soil organisms exposed to mandipropamid isomers. Therefore, the selective bioaccumulation of mandipropamid isomers and detoxification mechanisms of earthworms (Eisenia fetida) were investigated in this study. Our results suggested that the enantioselective bioaccumulation of mandipropamid in earthworms occurred with the preferential enrichment of S-(+)-isomer. The activities of detoxification enzymes, such as cytochrome P450 (CYP450), glutathione-S-transferases (GST), and carboxylesterase (CarE), changed significantly upon exposure to S-(+)- and R-(-)-mandipropamid (particularly for CYP450 and GST). A transcriptome analysis revealed that more differentially expressed genes (DEGs) were observed under S-(+)-isomer exposure (15,798) than those under R-(-)-isomer exposure (12,222), as compared to the control group. These DEGs were mainly enriched in bile secretion and thyroid hormone signaling pathways, which were related to the detoxification process in earthworms. Moreover, the 20 DEGs, which exhibited the most profound changes (such as CYP2 and CYP3A4) in these pathways, were screened, clustered, and observed to be mainly involved in regulating the detoxification function of earthworm cells. These results indicated that detoxification systems played an essential role in the stress response to mandipropamid exposure. Additionally, earthworms were more sensitive to the stress induced by S-(+)-mandipropamid than that induced by R-(-)-mandipropamid. This is the first study to elucidate the mandipropamid detoxification mechanism of earthworms at the enantiomer level, which can be beneficial for remediating chiral pollutants.

Current Strategies for Studying the Natural and Synthetic Bioactive Compounds in Food by Chromatographic Separation Techniques

The present study summarizes the new strategies including advanced equipment and validation parameters of liquid and gas chromatography methods i.e., thin-layer chromatography (TLC), column liquid chromatography (CLC), and gas chromatography (GC) suitable for the identification and quantitative determination of different natural and synthetic bioactive compounds present in food and food products, which play an important role in human health, within the period of 2019–2021 (January). Full characteristic of some of these procedures with their validation parameters is discussed in this work. The present review confirms the vital role of HPLC methodology in combination with different detection modes i.e., HPLC-UV, HPLC-DAD, HPLC-MS, and HPLC-MS/MS for the determination of natural and synthetic bioactive molecules for different purposes i.e., to characterize the chemical composition of food as well as in the multi-residue analysis of pesticides, NSAIDs, antibiotics, steroids, and others in food and food products.

Partially carbonized cellulose filter paper as a green adsorbent for the extraction of pesticides from fruit juices

In this study, a new solid phase extraction method based on the use of a low-cost funnel-shaped partially carbonized cellulose filter paper as a sorbent has been developed. The sorbent is easily prepared by heating the folded filter paper wetted with sulfuric acid solution and can be reused for several times. It is combined with dispersive liquid-liquid microextraction and used for the extraction of some pesticide residues from fruit juice samples prior to their analysis by gas chromatography-flame ionization detection. In this work, limits of detection and quantification were in the ranges of 0.30-0.61 and 1.0-2.0 µg L^-1, respectively, and relative standard deviations ranged between 3 and 6% for intra- (n=5) and inter-day (n=5) precisions at a concentration of 25 µg L^-1 of each pesticide. The enrichment factors of 452-751 were achieved. Extraction recoveries were in the range of 45-75%. The calibration curves had wide linear ranges with a good linearity (coefficient of determination ≥ 0.994). Finally, efficiency of the method was apprised by determining the analytes in fruit juice samples and relative recoveries were found to be in the range of 85-101%.

A rapid method for the simultaneous stereoselective determination of the triazole fungicides in tobacco by supercritical fluid chromatography-tandem mass spectrometry combined with pass-through cleanup

This work presents a simple, rapid and green chiral analysis method for five triazole fungicides (penconazole, tebuconazole, triadimefon, myclobutanil, and triadimenol) in tobacco, by which the samples were cleaned up by the novel pass-through solid phase extraction and subsequently the stereoisomers were separated and determined by the supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS). Optimized separation of the stereoisomers was achieved on an ACQUITY UPC2 Trefoil AMY 1 column within 6 min. Under fortified concentration levels of 0.1, 0.5 and 2.0 mg/kg, the mean recoveries were 82.8-106.6%, the intra-day relative standard deviations (RSDs) were 1.1-6.6%, and the inter-day RSDs were 2.5-5.6%. The correlation coefficient was greater than 0.9926 for all studied analytes within the range of 10-500 ng/mL. The limits of detection (LODs) for all stereoisomers ranged from 0.26 μg/kg to 3.24 μg/kg. The established method was subsequently successfully applied to analyze authentic samples, confirming that this method is a novel, rapid and environmentally friendly method for the stereoselective separation of triazole fungicides in tobacco.

Simultaneous determination, dissipation and decontamination of fungicides applied on cabbage using LC-MS/MS

A method for simultaneous determination of carbendazim and tebuconazole residues in cabbage was developed and validated in LC-MS/MS. Samples were extracted and purified following the modified QuEChERS procedure, which enabled the elution of carbendazim and tebuconazole at 0.96 and 5.31 min, respectively. LOD and LOQ were 0.0005 and 0.0015 mg kg^-1, respectively. Mean recovery was in the range of 78.94 to 104.89% for carbendazim and 76.07 to 98.62% for tebuconazole. The field samples recorded residues of 0.274 and 0.481 mg kg^-1; and 0.194 and 0.392 mg kg^-1 at single and double dose for carbendazim and tebuconazole, respectively. Half-life values were 2.17 and 2.99 for carbendazim and 2.74 and 2.81 for tebuconazole at single and double dose, respectively. Decontamination with saltwater wash followed by cooking and lemon water wash found superior in the removal of residues more than 90%.

Study on the stereoselective behaviors of fosthiazate stereoisomers in legume vegetables by supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS)

A separation and analysis method of fosthiazate stereoisomers was established utilizing supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS) with a CHIRALPAK AD-3 column. The determination of the four fosthiazate stereoisomers could be completed within 6 min. The environmental behaviors of fosthiazate stereoisomers were studied in legume vegetables. After applying fosthiazate granules to soil, the concentrations of fosthiazate stereoisomers in the legume vegetables increased with time, reached maximum values in 7-10 days, and then decreased gradually in all legumes except for in Glycine max. No obvious dissipation behaviors were observed in Glycine max. Interestingly, the stereoselective behaviors were species-specific. A-(-), B-(-) and B-(±)-fosthiazate were preferentially enriched in Phaseolus vulgaris Linn and Vigna unguiculata, while A-(+) and A-(±)-fosthiazate preferentially accumulated in Vicia faba Linn, Pisum sativum Linn and G. max. The opposite stereoselectivity of B-(±)-fosthiazate was observed in different growth stage of G. max. No stereoselective dissipation occurred in soil.

Effects of multi-walled carbon nanotubes on the enantioselective toxicity of the chiral insecticide indoxacarb toward zebrafish (Danio rerio)

The mass production and usage of carbon nanotubes (CNTs) have led to the inevitable release into the environment, and the effects of CNTs on the toxicity of co-existing pollutants have been well documented. However, knowledge of the effects of CNTs on the enantioselective toxicity of chiral compounds is limited. Using zebrafish as an experimental model, the enantioselective expression of the apoptosis, CYP3C and EAAT-related genes were analyzed following exposure to multi-walled carbon nanotubes (MWCNTs) (0.05 and 0.5 mg/L), rac-/R-/S-indoxacarb (0.01 mg/L), or the combination of rac-/R-/S-indoxacarb mixed with MWCNTs for 28d. Sex-specific differences were observed in both the liver and brain of zebrafish. The expression of apoptosis and CYP3C-related genes was 16.55-44.29 times higher in the livers of males treated with R-indoxacarb than in S-indoxacarb treated groups. The EAAT-related genes were expressed at 1.38-2.56 times higher levels in the brain of females treated with R-indoxacarb than in S-indoxacarb-treated groups. In the presence of MWCNTs, the expression of caspase-3, cyp3c3, cyp3c4, eaat1a, eaat1b and eaat2 in the livers of males and brains of females treated with S-indoxacarb were 1.65-15.33 times higher than in fish treated with R-indoxacarb. Based on these results, MWCNTs affected the enantioselective toxicity of indoxacarb toward zebrafish.

Analytical methods to analyze pesticides and herbicides

This paper reviews studies published in 2019, in the area of analytical techniques for determination of pesticides and herbicides. It should be noted that some of the reports summarized in this review are not directly related to but could potentially be used for water environment studies. Based on different methods, the literatures are organized into six sections, namely extraction methods, electrochemical techniques, spectrophotometric techniques, chemiluminescence and fluorescence methods, chromatographic and mass spectrometric techniques, and biochemical assays. PRACTITIONER POINTS: Totally 141 research articles have been summarized. The review is divided into six parts. Chromatographic and mass spectrometric techniques are the most widely used methods.

Quick and Sensitive Enantioselective Determination of Permethrin in Fruits and Vegetables by Combining Supramolecular Solvents and Chiral Liquid Chromatography-Tandem Mass Spectrometry

Permethrin (PM) is one of the chiral insecticides most widely used around the world. The significant differential toxicity of its four enantiomers and its important adverse effects on human health highlights the need for determination of PM enantiomers. The aim of this work was to develop the first enantioselective method for quantification of PM in fruits and vegetables. The method is based on the extraction of PM enantiomers in supramolecular solvents with restricted access properties (SUPRAS-RAM) and their separation/detection by chiral liquid chromatography-tandem mass spectrometry (LC-MS/MS) which is first reported in this article. SUPRAS-RAM-based extraction is proposed as an innovative treatment approach that drastically reduces solvent consumption and avoids the need for sample cleanup. Extraction of PM enantiomers is quick (vortexing for 5 min) and efficient (recoveries 93-107%). The method is sensitive (quantification limits from 1.0 to 1.2 μg kg^-1) and suitable for control of PM enantiomers in agri-food products.

The Current Role of Graphene-Based Nanomaterials in the Sample Preparation Arena

Since its discovery in 2004 by Novoselov et al., graphene has attracted increasing attention in the scientific community due to its excellent physical and chemical properties, such as thermal/mechanical resistance, electronic stability, high Young's modulus, and fast mobility of charged atoms. In addition, other remarkable characteristics support its use in analytical chemistry, especially as sorbent. For these reasons, graphene-based materials (GBMs) have been used as a promising material in sample preparation. Graphene and graphene oxide, owing to their excellent physical and chemical properties as a large surface area, good mechanical strength, thermal stability, and delocalized π-electrons, are ideal sorbents, especially for molecules containing aromatic rings. They have been used in several sample preparation techniques such as solid-phase extraction (SPE), stir bar sorptive extraction (SBSE), magnetic solid-phase extraction (MSPE), as well as in miniaturized modes as solid-phase microextraction (SPME) in their different configurations. However, the reduced size and weight of graphene sheets can limit their use since they commonly aggregate to each other, causing clogging in high-pressure extractive devices. One way to overcome it and other drawbacks consists of covalently attaching the graphene sheets to support materials (e.g., silica, polymers, and magnetically modified supports). Also, graphene-based materials can be further chemically modified to favor some interactions with specific analytes, resulting in more efficient hybrid sorbents with higher selectivity for specific chemical classes. As a result of this wide variety of graphene-based sorbents, several studies have shown the current potential of applying GBMs in different fields such as food, biological, pharmaceutical, and environmental applications. Within such a context, this review will focus on the last five years of achievements in graphene-based materials for sample preparation techniques highlighting their synthesis, chemical structure, and potential application for the extraction of target analytes in different complex matrices.

Enantioseparation and Determination of Penconazole in Rat Plasma by Chiral LC-MS/MS: Application to a Stereoselective Toxicokinetic Study

In this study, a specific and sensitive method of liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was developed for the determination of penconazole enantiomers in rat plasma. The enantioseparation was achieved on a Chiralpak IC column by using acetonitrile/water (80:20, v/v) as the mobile phase. Penconazole enantiomers and internal standard l-lansoprazole (IS) were detected in multiple reaction monitoring (MRM) mode with positive electrospray ionization source. The method was validated over the concentration range of 2.5–250.0 ng mL⁻¹ for penconazole enantiomers. Good linearity was obtained for both enantiomers with correlation coefficients (R) greater than 0.995. The relative error was well within the admissible range of −1.1–3.2%, and relative standard deviation was less than 6.0%. After validation, the established method was successfully applied to a stereoselective toxicokinetic study in female and male rats after oral administration of 50 mg kg⁻¹ racemic penconazole. This is the first experiment regarding the stereospecific toxicokinetic study of penconazole and the bioanalytical approach for its quantitation in vivo.

A magnetic multi-walled carbon nanotube preparative method for analyzing asymmetric carbon, phosphorus and sulfur atoms of chiral pesticide residues in Chinese herbals by chiral liquid chromatography-quadrupole/linear ion trap mass spectrometry determination

An analytical method for the determination of asymmetric carbon, phosphorus and sulfur atoms in chiral pesticide residues by magnetic multi-walled carbon nanotube sample pretreatment combined with chiral ultra-performance liquid chromatography/quadrupole/linear ion trap mass spectrometry (UPLC-MS/Qtrap) was developed and applied to chiral pesticide residues analysis in Chinese herbals. Eleven different chiral pesticides were found, and 36.4% were positive in Chinese herbals. Three plants containing detectable pesticide residues were observed in Dendrobium nobile, Panax notoginseng flowers and honeysuckle, in the order of decreasing detected concentration. High detection frequencies of 26.1% for (R/S)-(±)-difenoconazole and 14.5% for (R/S)-(±)-metalaxyl and (R/S)-(±)-propiconazole were observed, the residual amount for (R/S)-(±)-difenoconazole, (R/S)-(±)-metalaxyl and (R/S)-(±)-propiconazole were 0.32 ~ 2.5 mg/kg, 0.022 ~ 0.23 mg/kg, 0.62 ~ 3.21 mg/kg respectively. The EF value of (R/S)-(±)-difenoconazole was 0.506 ± 0.046. The EF value of (R/S)-(±)-metalaxyl was lower than 0.5 in Dendrobium nobile, Panax notoginseng flowers, Panax notoginseng roots and hawthorn. The EF of (R/S)-(±)-propiconazole was not significantly enantioselective in honeysuckle and Panax notoginseng flowers. The enantioselectivity of various pesticide residues in different plants cannot be predicted from our existing knowledge and may closely depend on plant growth, environmental conditions or molecular structure.

Further study on enantiomer resolving ability of amylose tris(3-chloro-5-methylphenylcarbamate) covalently immobilized onto silica in nano-liquid chromatography and capillary electrochromatography

In the present study separation of enantiomers of some chiral neutral, basic and weakly acidic analytes was investigated on the chiral stationary phase (CSP) made by covalent immobilization of amylose tris(3-chloro-5-methylphenylcarbamate) onto aminopropylsilanized (APS) silica in nano-liquid chromatography (nano-LC) in aqueous methanol or acetonitrile mixtures. It has been shown that similar to high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) this chiral selector is useful for separation of enantiomers of neutral, basic and acidic analytes also in nano-LC. In comparison to our previous research, in which the chiral selector (CS) was bonded on native silica, in this study, the CS was immobilized on APS silica in order to improve chromatographic performance towards basic analytes. In fact, some improvement was observed and surprisingly not only for basic but also for neutral and acidic analytes. Again, quite unexpectedly almost no electroosmotic flow (EOF) was observed in capillaries packed with ca. 20% (w/w) amylose tris(3-chloro-5-methylphenylcarbamate) immobilized onto APS silica although the same APS silica before attachment of chiral selector exhibited significant EOF. In order to generate EOF in the capillaries with the CSP and enable capillary electrochromatographic (CEC) experiment on it, the short segment of the capillary column was packed with APS silica without chiral selector. The EOF in such capillary enabled CEC experiment and some preliminary results are reported here.

Simultaneous enantioselective determination of seven psychoactive drugs enantiomers in multi-specie animal tissues with chiral liquid chromatography coupled with tandem mass spectrometry

In stock farming, illegal use of antipsychotics has caused the food safety problem. This paper presents for the first time, a multi-residues method for the simultaneous enantioselective determination of seven antipsychotics in pork, beef and lamb muscles. The behaviors of Chiralpak AGP toward changes in pH and organic modifier in mobile phase were studied, and all analytes were rapidly separated within 30 min. The calibration curves of all enantiomers were linear in the range of 1-250 ng g^-1, with correlation coefficient above 0.9931. The recoveries of the targeted compounds were higher than 82.1%, with repeatability and intermediate precision lower than 18.2% and 17.4%, respectively. In three matrices, the limit of detection and limit of quantification ranged from 0.20 to 0.65 ng g^-1 and from 0.40 to 1.00 ng g^-1, respectively. The proposed method can be used to provide additional information for the reliable risk assessment of chiral antipsychotics.

Enantioselective degradation of chiral fungicides triticonazole and prothioconazole in soils and their enantioselective accumulation in earthworms Eisenia fetida

Triticonazole and prothioconazole are widely used systemic agricultural triazole fungicides both with a chiral center. In this work, the enantioselective degradation of triticonazole and prothioconazole in three types of soils were investigated under native conditions using reversed phase liquid chromatography-tandem mass spectrometry with a Chiralcel OD-RH column. The results indicated that the enantioselective degradation was observed with S-triticonazole and R-prothioconazole preferentially degraded and the degradation rate was fast with a half-life within 6 days. It was also found that the presence of earthworms can accelerate the degradation and further enhance degradation enantioselectivity of triticonazole and prothioconazole in soils. Moreover, the enantioselective of triticonazole and prothioconazole in earthworms were studied. The results showed that the bioaccumulation was enantioselective with R-triticonazole and S-prothioconazole preferentially accumulated, which was similar to the soil. Our findings suggest that the enantioselective toxicity and potential effects of the metabolites should be considered for more accurate assessment of ecological risks of triticonazole and prothioconazole to target and non-target species.

Application and enantioselective residue determination of chiral pesticide penconazole in grape, tea, aquatic vegetables and soil by ultra performance liquid chromatography-tandem mass spectrometry

Penconazole is a typical triazole fungicide with wide use on fruits, vegetables, and tea plants to control powdery mildew. In the present study, an efficient graphite carbon black solid phase extraction (GCB-SPE) purification combined with chiral ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed for determination of penconazole enantiomers in different complex matrices, including grape, tea, soil, lotus root, lotus leaf, lotus seed and hulls. The method was then applied to investigate the enantioselective dissipation of penconazole enantiomers in a real field experiment of grape and soil. As a result, a satisfactory separation of penconazole enantiomers on a chiral Lux Cellulose-2 column (150 mm × 2 mm i.d., 3 µm) was obtained with 0.1% formic acid in methanol and 10 mmol L^-1 ammonium acetate in water (75/25, v/v) as mobile phase at 0.25 mL min^-1. The enantiomer (+)-penconazole was firstly eluted, and (-)-penconazole was then eluted. The method showed reliable performances in linearity, recovery and precision, the recoveries of (+)-penconazole and (-)-penconazole in all of six matrices were between 70.5% and 121.0% with the relative standard deviations (RSDs) ranging from 0.8% to 23.6% at the low, medium and high spiked levels. The limits of quantitation (LOQs) of this method were lower than 0.0025 mg kg^-1 in grape, soil and lotus root, 0.005 mg kg^-1 in lotus leaf, lotus seed meat and lotus seed shell, and 0.0125 mg kg^-1 in tea. Results of field trials indicated that (-)-penconazole degraded faster than its (+)-isomer in grape. While only a moderate stereoselectivity was observed in soil, with (-)-penconazole preferential degraded. The proposed method could be used to investigate enantioselective environmental behavior of penconazole enantiomers in complex matrices. And results in this study could provide useful information on realistic risk assessment of penconazole in grape.

Enantioseparation of flurbiprofen enantiomers using chiral ionic liquids by liquid-liquid extraction

Flurbiprofen is a kind of nonsteroidal anti-inflammatory drug, which has been widely used in clinic for treatment of rheumatoid arthritis and osteoarthritis. It has been reported that S-flurbiprofen shows good performance on clinic anti-inflammatory treatment, while R-enantiomer almost has no pharmacological activities. It has important practical values to obtain optically pure S-flurbiprofen. In this work, chiral ionic liquids, which have good structural designability and chiral recognize ability, were selected as the extraction selector by the assistance of quantum chemistry calculations. The distribution behaviors of flurbiprofen enantiomers were investigated in the extraction system, which was composed of organic solvent and aqueous phase containing chiral ionic liquid. The results show that maximum enantioselectivity up to 1.20 was attained at pH 2.0, 25°C using 1,2-dichloroethane as organic solvent, 1-butyl-3-methylimidazole L-tryptophan ([Bmim][L-trp]) as chiral selector. The racemic flurbiprofen initial concentration was 0.2 mmol L^-1 , and [Bmim][L-trp] concentration was 0.02 mol L^-1 . Furthermore, the recycle of chiral ionic liquids has been achieved by reverse extraction process of the aqueous phase with chiral selector, which is significant for industrial application of chiral ionic liquids and scale-up of the extraction process.

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.