Enantioselective determination of triazole fungicide simeconazole in vegetables, fruits, and cereals using modified QuEChERS (quick, easy, cheap, effective, rugged and safe) coupled to gas chromatography/tandem mass spectrometry

Triazoles in the environment: An update on sample pretreatment and analysis methods

Triazoles, due to their high bactericidal performance, have been widely used in the agricultural, clinical, and chemical industry. However, triazoles have been proven to cause endocrine-toxic and organ impairment in humans as a potentially toxic substance. Besides, because of the improper use and difficulty of degradation, triazoles pesticide residues left in the environment could pose a threat to the environment. Therefore, the rapid, reliable, accurate, and high-sensitivity triazoles analysis methods are significantly essential to effectively monitor their presence in various samples and safeguard human health. This review aims to summarize and update the progress of the pretreatment and analytical methods of triazole fungicides in environmental samples from 2012 to 2024. Common pretreatment methods used to extract and purify targets include simple steps (e.g., protein precipitation and coated blade spray), liquid-liquid extraction, solid-phase extraction, and various microextraction methods such as liquid-phase microextraction and solid-phase microextraction, among others. Detection methods mainly include liquid chromatography-mass spectrometry, gas chromatography-mass spectrometry, supercritical fluid chromatography, sensing methods, and capillary electrophoresis. In addition, we elaborate and compare the advantages and disadvantages of different pretreatment and analytical methods, and their development prospects are discussed.

Method Validation and Measurement Uncertainty Estimation for Determination of Multiclass Pesticide Residues in Tomato by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Method validation is an essential technique for ensuring the reliability and accuracy of an analytical method. This study aimed to optimize and validate a fast, reliable, and accurate method for quantitatively determining pesticide residues of diverse chemical classes in the tomato matrix. Various method performance characteristics were tested and compared with predefined criteria. Twenty-six different pesticides of diverse chemical classes were selected based on their use in tomato cultivation and the availability of reference materials. The pesticide residues in tomato samples were extracted with the QuEChERS technique with some modifications, followed by injection into an LC-MS/MS system operating in an optimized method. The validated method demonstrated reasonable specificity, as there were no interferences from matrix components at the retention times of pesticides. The calibration curves for all pesticides exhibited excellent linearities, with correlation coefficients exceeding 0.99. No significant matrix effect was observed for all pesticides in tomatoes, as the values fell within the range of ±20%. All pesticides were quantified successfully at a concentration of 5 μg/kg except for carbaryl, with an average recovery of more than 70% and a relative standard deviation of less than 20%. Similarly, measurement uncertainties were also estimated based on the validation data, and the values were found below the default limit of 50%. Subsequently, the validated method was applied to analyze 52 locally collected tomato samples. Study findings revealed that only four of the studied pesticides were detected in these samples, and their concentrations were below the maximum residue limits (500 µg/kg each for carbendazim, imidacloprid, and metalaxyl) established for tomatoes by the Government of Nepal and the Codex Alimentarius Commission.

Simultaneous determination of triazole fungicides in animal-origin food by ultra-high-performance liquid chromatography coupled with tandem mass spectrometry

A method for the simultaneous determination of 21 triazole fungicides in animal-origin foods was established by using UPLC-MS/MS. The dilution solvent, extraction solvent, and QuEChERS purification adsorbent composition, were optimized. The response value of the target compound was the highest and the chromatographic peak shape was optimal under the following conditions: water-acetonitrile as the mobile phase, acetonitrile to extract the target compound, C18 (100 mg) as the adsorbent, and water-acetonitrile as the diluent. Our method was validated under electrospray ionization (ESI) + conditions with six animal-origin foods. The 21 triazole fungicides showed good linear relationships (0.1-20 μg∙L-1, R2 > 0.99). The limits of detection and quantitation ranged from 0.1 to 0.3 μg∙kg-1 and 0.3 to 0.9 μg∙kg-1, respectively. The average recoveries ranged from 72.0% to 114.8% with RSDs < 9.9%. Therefore, our method was suitable for the determination of pesticide residues in commercially available animal-origin samples.

Dual-comb optical activity spectroscopy for the analysis of vibrational optical activity induced by external magnetic field

Optical activity (OA) spectroscopy is a powerful tool to characterize molecular chirality, explore the stereo-specific structure and study the solution-state conformation of biomolecules, which is widely utilized in the fields of molecular chirality, pharmaceutics and analytical chemistry. Due to the considerably weak effect, OA spectral analysis has high demands on measurement speed and sensitivity, especially for organic biomolecules. Moreover, gas-phase OA measurements require higher resolution to resolve Doppler-limited profiles. Here, we show the unmatched potential of dual-comb spectroscopy (DCS) in magnetic optical activity spectroscopy (MOAS) of gas-phase molecules with the resolution of hundred-MHz level and the high-speed measurement of sub-millisecond level. As a demonstration, we achieved the rapid, high-precision and high-resolution MOAS measurement of the nitrogen dioxide [Formula: see text]+[Formula: see text] band and the nitric oxide overtone band, which can be used to analyze fine structure of molecules. Besides, the preliminary demonstration of liquid-phase chiroptical activity (as weak as 10^-5) has been achieved with several seconds of sampling time, which could become a routine approach enabling ultrafast dynamics analysis of chiral structural conformations.

Enantioseparation of ketoconazole and miconazole by capillary electrophoresis and a study on their inclusion interactions with β-cyclodextrin and derivatives

A chiral separation method coupled with capillary electrophoresis (CE) analysis for ketoconazole and miconazole enantiomers using chiral selectors such as β-cyclodextrin (β-CD) and hydroxypropyl-β-CD (HP-β-CD) was developed in this study, which included the optimisation, validation and application of the method on the antifungal cream samples. The formation of inclusion complex between the hosts (β-CD and HP-β-CD) and guests (ketoconazole and miconazole) were compared and analysed using ultraviolet-visible spectrophotometry, nuclear magnetic resonance (NMR) spectroscopy and molecular docking methods. Results from the study showed that in a concentration that ranged between 0.25 and 50 mg L^-1 , the linear calibration curves of each enantiomer had a high coefficient of regression (R² > 0.999), low limit of detection (0.075 mg L^-1 ) and low limit of quantification (0.25 mg L^-1 ). The relative standard deviation (RSD) of the intraday and interday analyses ranged from 0.79% to 8.01% and 3.30% to 11.43%, respectively, while the recoveries ranged from 82.0% to 105.7% (RSD < 7%, n = 3). The most probable structure of the inclusion complexes was proposed based on the findings from the molecular docking studies conducted using the PatchDock server.

Assessment of magnetic core-shell mesoporous molecularly imprinted polymers for selective recognition of triazoles residual levels in cucumber

Functional magnetic nanomaterials based on molecular imprinting technique were successfully prepared on the surface of modified Fe₃O₄. Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometer, and vibrating sample magnetometry were applied for characterization of the synthesized magnetic nanoparticles. The magnetic molecularly imprinted polymers (MMIPs) exhibited satisfactory magnetic response, specific recognition, and excellent adsorption capacity toward triazoles (maximum adsorption capacity of 9202.9 μg g^-1 for triadimefon). The obtained MMIPs were further used as magnetic dispersive solid-phase extraction (MDSPE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for detection of 20 triazoles in cucumber spiked at different levels. The mean recoveries were ranged from 79.9% to 110.3% and relative standard deviations (RSDs) were <11.2% (n = 5). Herein, we report a simple, rapid, environmentally friendly, and magnetic stuff recyclable approach for triazoles residual analysis in complicated agricultural products.

Stereoselective bioactivity of the chiral triazole fungicide prothioconazole and its metabolite

Chiral triazole fungicides have played a significant role in plant pathogen control. Although their enantiomers often exhibit different bioactivity, the mechanism of the stereoselectivity has not been well studied. The stereoselective bioactivity and mechanisms of prothioconazole and its chiral metabolite against plant pathogenic fungi were investigated. The results indicated that the metabolite exerted more fungicidal activities than the activities of the parent compound. R-Prothioconazole and R-prothioconazole-desthio were 6-262 and 19-954 times more potent against pathogenic fungi than the S-enantiomers, respectively. The R-enantiomers were more effective than in inhibiting the biosynthesis of ergosterol and deoxynivalenol the S-enantiomer. Homology modeling and molecular docking suggested that the R-enantiomers of prothioconazole and prothioconazole-desthio possessed better binding modes than S-enantiomers to CYP51B. Moreover, exposure to prothioconazole and its metabolite enantiomers significantly changed the transcription levels of the CYP51 (CYP 51A, CYP51B, CYP 51C) and Tri (Tri5, Tri6, Tri12) genes. The results showed that application of the R-prothioconazole could require a smaller application amount to eliminate the carcinogenic mycotoxins and any environmental risks.

Rice Grain Quality Benchmarking Through Profiling of Volatiles and Metabolites in Grains Using Gas Chromatography Mass Spectrometry

Gas chromatograph coupled with mass spectrometer is widely used to profile volatiles and metabolites from the homogenized rice flour obtained from mature grains. Rice grains consist of central endosperm which stores majorly starch and, in addition, accumulate various storage proteins as storage reserves. The outer nutritious aleurone layer stores lipids, sugar alcohols, volatiles, antioxidants, vitamins, and various micronutrients. Once paddy sample is dehulled, milled, and ground cryogenically, the brown rice flour is subjected to extraction of primary metabolites and volatiles using an appropriate extraction method. In metabolite profiling of the liquid extract obtained from the rice sample, mixture is initially subjected to methoxyamination then silylation before being subjected to untargeted metabolite profiling. Peaks obtained are processed for noise reduction and specific signal selection. Volatile compounds are initially extracted using a solid phase adsorbent prior to analysis. All these compounds, metabolites, and volatiles are detected in the mass selective detector by fragmentation at 70 eV ionization energy and the resultant mass spectrum compared with a built-in library of compounds. Data mined from the gas chromatography mass spectrometry analysis are then subjected to post-processing statistical analysis.

Stereoselective Separation of the Fungicide Bitertanol Stereoisomers by High-Performance Liquid Chromatography and Their Degradation in Cucumber

Bitertanol is a widely used triazole fungicide and consists of four stereoisomers. A new high-performance liquid chromatography (HPLC) method was developed for simultaneous analysis of the four stereoisomers in apple, pear, tomato, cucumber, and soil. The mechanism of separation was explained with molecular docking and effects of thermodynamic parameters on the resolution. The absolute configuration and optical rotation of four stereoisomers were confirmed by X-ray diffraction and HPLC tandem circular dichroism, respectively. A good linearity ( R² ≥ 0.999) was obtained for four stereoisomers in all matrix-matched calibration curves in the range of 0.02-10 mg/L. The mean recoveries of four stereoisomers in five matrices ranged from 74.6% to 101.0% with an intraday and interday relative standard deviation from 0.6% to 9.9%. Stereoselective degradation of bitertanol in cucumber was observed: (1 R,2 S)-bitertanol and (1 R,2 R)-bitertanol were preferentially degraded with enantiomeric fraction values from 0.5 to 0.43 at 7 d and 0.42 at 5 d, respectively. This research provides a useful tool for the analysis of bitertanol stereoisomers.

Enantioseparation and determination of dufulin enantiomers in cucumber and soil by chiral liquid chromatography-tandem mass spectrometry

A simple and rapid method for enantioselective determination of dufulin in cucumber and soil was developed by liquid chromatography with tandem mass spectrometry. The enantiomers were separated on a Superchiral S-OD chiral cellulose tris(3,5-dimethylphenylcarbamate) column at 20°C, with a mixture of acetonitrile and water (0.1% formic acid; 52:48, v/v) as mobile phase at a flow rate of 0.65 mL/min. The pretreatment conditions were optimized using an orthogonal test, and the optimized method showed good linearity and sensitivity. The limits of detection and limits of quantification of two dufulin enantiomers were 0.006 and 0.02 mg/kg, respectively. The average recoveries of S-enantiomer and R-enantiomer in cucumber and soil were 80.61-99.83% and 80.97-102.96%, respectively, with relative standard deviations of 1.30-9.72%. The method was successfully applied to determine dufulin in real cucumber and soil samples. The results demonstrate that the method could facilitate further research on the differences between individual dufulin enantiomers with respect to metabolites and environmental fate and finally help reveal the complex interactions that exist between dufulin, humans and the environment.

Effervescence-assisted dispersive solid-phase extraction using ionic-liquid-modified magnetic β-cyclodextrin/attapulgite coupled with high-performance liquid chromatography for fungicide detection in honey and juice

In this study, a simple effervescence-assisted dispersive solid-phase extraction method was developed to detect fungicides in honey and juice. Most significantly, an innovative ionic-liquid-modified magnetic β-cyclodextrin/attapulgite sorbent was used because its large specific surface area enhanced the extraction capacity and also led to facile separation. A one-factor-at-a-time approach and orthogonal design were employed to optimize the experimental parameters. Under the optimized conditions, the entire extraction procedure was completed within 3 min. In addition, the calibration curves exhibited good linearity, and high enrichment factors were achieved for pure water and honey samples. For the honey samples, the extraction efficiencies for the target fungicides ranged from 77.0 to 94.3% with relative standard deviations of 2.3-5.44%. The detection and quantitation limits were in the ranges of 0.07-0.38 and 0.23-1.27 μg/L, respectively. Finally, the developed technique was successfully applied to real samples, and satisfactory results were achieved. This analytical technique is cost-effective, environmentally friendly, and time-saving.

Evaluation of alternative sorbents for dispersive solid-phase extraction clean-up in the QuEChERS method for the determination of pesticide residues in rice by liquid chromatography with tandem mass spectrometry

Many compounds are used for pest control during the production and storage of rice, making it necessary to employ multiclass methods for pesticide residues determination. For this purpose, QuEChERS-based methods are very efficient, fast and accurate, and improvements in the clean-up step are important, especially for complex matrices, like cereals. In this work, different sorbents such as chitosan, florisil(®) , alumina, diatomaceous earth, graphitized carbon black, besides the commonly used primary secondary amine and octadecylsilane, were evaluated for dispersive solid-phase extraction clean-up in acetate-buffered QuEChERS method for the determination of residues of 20 representative pesticides and one metabolite in rice by liquid chromatography coupled to tandem mass spectrometry. The sorbent C18 presented the best results, however, chitosan showed similar results, and the best performance among the unconventional sorbents evaluated. The method limit of quantification, attending accuracy (70-120% recovery) and precision (RSD ≤20%) criteria, ranged from 5 to 20 μg/kg. Results showed that chitosan is an effective alternative to reduce analysis costs, maintaining the method reliability and accuracy.

Stereoselective degradation of flutriafol and tebuconazole in grape

The stereoselective dissipation of flutriafol and tebuconazole in grape had been studied. A simple and sensitive method for determination of flutriafol and tebuconazole enantiomers in grape was developed by high-performance liquid chromatography on a cellulose tris(3-chloro-4-methylphenylcarbamate) column. The limits of quantification for flutriafol and tebuconazole in grape were 0.033 and 0.043 mg kg(-1), respectively. The dissipations of flutriafol and tebuconazole stereoisomers in grape followed first-order kinetics (R (2) > 0.93). The stereoisomers of flutriafol and tebuconazole were enantioselectively degraded in grape, and tebuconazole was more enantioselective than flutriafol. The half-life of (-)-tebuconazole was 5.2 days and shorter than (+)-tebuconazole with half-life of 6.4 days. The (-)-flutriafol was also preferentially degraded in grape, the half-lives of which were 6.59 and 6.98 days for (-) and (+)-flutriafol, respectively. The enantiomeric ratio value of the two fungicides was nearly 1.0 at the 1st day and increased to 1.143 for flutriafol and 2.015 for tebuconazole at the 28th day. The stereoselective dissipations could provide a reference to fully evaluate the risks of two important chiral triazole fungicides.

Simultaneous enantioselective determination of triazole fungicide flutriafol in vegetables, fruits, wheat, soil, and water by reversed-phase high-performance liquid chromatography

A novel and effective method for enantioselective determination of flutriafol enantiomers in food and environmental matrices (cucumber, tomato, grape, pear, wheat, soil, and water) has been developed. The (R)-(-)-flutriafol was first eluted and measured from electronic circular dichroism spectra using a cellulose tris(3-chloro-4-methyl phenyl carbamate) chiral column. The mean recoveries from the samples ranged from 82.9% to 103.4%, with intraday relative standard deviations (RSD) of 2.2-8.3% and interday RSD of 3.4-7.9%. Good linearity (R(2) ≥ 0.9989) was obtained for all analytes matrix calibration curves within the range of 0.1-10 mg/kg. The limits of detection for two enantiomers in the seven matrices were all below 0.015 mg/kg. The results show that the proposed method is convenient and reliable for the enantioselective detection of the flutriafol in the real samples and is applicable to the environmental stereochemistry of flutriafol in food and environmental matrices.

Determination of pesticide residues in honeybees using modified QUEChERS sample work-up and liquid chromatography-tandem mass spectrometry

Increasing emissions of chemical compounds to the environment, especially of pesticides, is one of factors that may explain present honeybee colony losses. In this work, an analytical method employing liquid chromatography-tandem mass spectrometry (LC-MS/MS) was optimized for the simultaneous screening of 19 pesticides which have not been yet determined in honeybee samples from northern Poland (Pomerania). The sample preparation, based on the QuEChERS method combining salting-out liquid-liquid extraction to acetonitrile and a dispersive-SPE clean-up, was adjusted to honeybee samples by adding a small amount of hexane to eliminate beeswax. The recovery of analytes ranged from 70% to 120% with relative standard deviation ≤20%. The limits of detection were in the range of 0.91–25 ng/g. A total of 19 samples of honeybees from suspected pesticide poisoning incidents were analyzed, in which 19 different pesticides were determined.

Determination of currently used pesticides in biota

Although pesticides enable control of the quantity and quality of farm products and food, and help to limit diseases in humans transmitted by insects and rodents, they are regarded as among the most dangerous environmental contaminants because of their tendency to bioaccumulate, and their mobility and long-term effects on living organisms. In the past decade, more analytical methods for accurate identification and quantitative determination of traces of pesticides in biota have been developed to improve our understanding of their risk to ecosystems and humans. Because sample preparation is often the rate-determining step in analysis of pesticides in biological samples, this review first discusses extraction and clean-up procedures, after a brief introduction to the classes, and the methods used in the analysis of pesticides in biota. The analytical methods, especially chromatographic techniques and immunoassay-based methods, are reviewed in detail, and their corresponding advantages, limitations, applications, and prospects are also discussed. This review mainly covers reports published since 2008 on methods for analysis of currently used pesticides in biota.