Enantioseparation and determination of isofenphos-methyl enantiomers in wheat, corn, peanut and soil with Supercritical fluid chromatography/tandem mass spectrometric method

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.

Toxic effects of isofenphos-methyl on zebrafish embryonic development

Isofenphos-methyl (IFP) is widely used as an organophosphorus for controlling underground insects and nematodes. However, excessive use of IFP may pose potential risks to the environment and humans, but little information is available on its sublethal toxicity to aquatic organisms. To address this knowledge gap, the current study exposed zebrafish embryos to 2, 4, and 8 mg/L IFP within 6-96 h past fertilization (hpf) and measured mortality, hatching, developmental abnormalities, oxidative stress, gene expressions, and locomotor activity. The results showed that IFP exposure reduced the rates of heart and survival rate, hatchability, and body length of embryos and induced uninflated swim bladder and developmental malformations. Reduction in locomotive behavior and inhibition of AChE activity indicated that IFP exposure may induce behavioral defects and neurotoxicity in zebrafish larvae. IFP exposure also led to pericardial edema, longer venous sinus-arterial bulb (SV-BA) distance, and apoptosis of the heart cells. Moreover, IFP exposure increased the accumulation of reactive oxygen species (ROS) and the content of malonaldehyde (MDA), also elevated the levels of antioxidant enzymes of superoxide dismutase (SOD) and catalase (CAT), but decreased glutathione (GSH) levels in zebrafish embryos. The relative expressions of heart development-related genes (nkx2.5, nppa, gata4, and tbx2b), apoptosis-related genes (bcl2, p53, bax, and puma), and swim bladder development-related genes (foxA3, anxa5b, mnx1, and has2) were significantly altered by IFP exposure. Collectively, our results indicated that IFP induced developmental toxicity and neurotoxicity to zebrafish embryos and the mechanisms may be relevant to the activation of oxidative stress and reduction of acetylcholinesterase (AChE) content.

Process Development for the Instant Quantification of Lycopene from Agricultural Produces Using Supercritical Fluid Chromatography-Diode Array Detector (SFC-DAD)

A quick, simple, and reliable isocratic ultra-performance supercritical fluid chromatography-photodiode array detector (UPSFC-DAD) method was developed and validated to determine lycopene in different horticultural products. The effects of stationary phase, co-solvent, pressure, temperature, flow rate, and mobile phase additive on the separation of lycopene were evaluated. The developed method involved BEH-2EP—2.1 × 150 mm, 5 µm as the stationary phase, and CO2/MeOH 85:15 (v/v) with formic acid as the additive at 0.10% as the mobile phase. The column temperature was maintained at 45 °C, ABPR at 1800 psi, and the mobile phase’s flow rate was maintained at 1 mL/min. Under the optimized conditions, lycopene was successfully separated within 0.722 ± 0.001 min. The standard curve assayed over a range of 10 to 100 µg/mL resulted in a correlation coefficient of 0.998. The mean recoveries between 97.38% and 102.67% at different spiking levels with RSD < 2.5% were achieved. The intra and inter-day precision expressed as relative standard deviations (RSD) were found to range from 1.27% to 3.28% and from 1.57% to 4.18%, respectively. Robustness in terms of retention time (tR) and RSD were found to be 0.93 ± 0.23 min and less <2.80%, respectively. The limits of detection and quantification were 0.14 µg/mL and 0.37 µg/mL, respectively. This method was successfully applied to determine lycopene extracted from papaya, grapefruit, and bitter melon.

Simultaneous determination of pinoxaden, cloquintocet-mexyl, clodinafop-propargyl ester and its major metabolite in barley products and soil using QuEChERS modified with multi-walled carbon nanotubes coupled with LC-MS/MS

Herein, a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method with multi-walled carbon nanotube (MWCNT) as a dispersive solid-phase extraction was developed for simultaneous determination of pinoxaden (PXD), cloquintocet-mexyl (CLM), clodinafop-propargyl ester (CPE) and its major metabolite (clodinafop, CP) in barley grass powder, barley grain, and soil using liquid chromatography-tandem mass spectrometry (LC-MS/MS). We found that MWCNT as an absorbent could improve the recoveries of the tested analytes, particularly CP, in complex matrices. Under the optimum conditions, the established MWCNT modified QuEChERS coupled with LC-MS/MS method exhibited excellent linearity (R² ) of ≥ 0.9912, low limits of detection (LODs) and quantification (LOQs) of 0.02-0.07 and 0.29-1.26 μg/kg, and acceptable recoveries of 80-130% with intra-and inter-day relative standard deviations (RSDs) < 10.5%. No strong matrix effect (ME) has been observed on the respective samples. The method was successfully applied to monitor the tested analytes in the representative field incurred samples. Conclusively, the proposed method is sensitive and reliable and could be used to monitor the residues of PDX, CLM, CPE, and CP in complicated agro-products and soil matrices.

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.

Separation of N'-nitrosonornicotine isomers and enantiomers by supercritical fluid chromatography tandem mass spectrometry

N'-nitrosonornicotine (NNN) is one of the most prevalent and toxic tobacco-specific nitrosoamines. A chiral center at its 2'-position results in R and S enantiomers, the partial double bond character of the NN = O group also results in E and Z isomers, therefore, NNN can form a total of four absolute configurations (E-(R)-NNN, E-(S)-NNN, Z-(R)-NNN, and Z-(S)-NNN). This study investigated the resolution of R/S enantiomers and E/Z isomers of NNN by supercritical fluid chromatography tandem mass spectrometry (SFC-MS/MS). The baseline separation of E/Z-(R,S)-NNN isomers/enantiomers was accomplished through the optimization of chiral columns and co-solvents. Due to the lack of single standard of E/Z isomers, only R-NNN (sum of E-(R)-NNN and Z-(R)-NNN) and S-NNN (sum of E-(S)-NNN and Z-(S)-NNN) were further examined. Through the comprehensive optimization of SFC-MS/MS conditions, R-NNN and S-NNN were separated with a run time of 5 min, the developed method was validated, and its applicability to the determination of NNN enantiomers in burley tobacco samples was demonstrated. This study could be applied to preparative separation of single enantiomer and/or isomer of NNN, and could provide potential benefits to biologic activity studies on these enantiomers and isomers.

Method development and validation of ten pyrethroid insecticides in edible mushrooms by Modified QuEChERS and gas chromatography-tandem mass spectrometry

A method for simultaneous determination of ten pyrethroid insecticides residues in edible mushrooms was developed. The samples were pretreated by a quick, easy, cheap, effective, rugged (QuEChERS) method. The ten pyrethroid insecticides were extracted from six kinds of edible mushrooms using acetonitrile and subsequently cleaned up by octadecylsilane (C18) or primary secondary amine (PSA). Instrumental analysis was completed in 16 min using gas chromatography-tandem mass spectrometry (GC-MS/MS). The overall average recoveries in the six kinds of edible mushrooms at three levels (10, 100 and 1000 μg kg^-1) ranged from 72.8% to 103.6%. The intraday and interday relative standard deviations (RSD) were lower than 13.0%. The quantification limits were below 5.57 μg kg^-1 in different matrices. The results demonstrated that the method is convenient for the quick detection of pyrethroid insecticides in edible mushrooms.

Supercritical Fluid Extraction of Pesticides and Insecticides from Food Samples and Plant Materials

The principal intention of this study is presenting the attempts carried out for extracting, separating, and determining of the pesticide and insecticide residues existing in food and plant samples. In this regard, a set of content, including the explanations about the supercritical fluid extraction (SFE), supercritical fluid chromatography, and various types of pesticides are indicated. Besides, the parameters affecting the pesticides extraction composed of temperature, pressure, modifier, drying agent, and so on are discussed. Also, examples of insecticides extraction by SFE technique as an important subset of pesticides are indicated. Along with these items, some interesting works, concerning the innovations implemented in the field of SFE of pesticide and insecticide residues from foodstuff and plants are depicted.

Spatiotemporal variations of pharmacologically active compounds in surface waters of a summer holiday destination

The release of pharmacologically active compounds (PhACs) into aquatic ecosystems poses an environmental risk resulting in a chronic exposure of non-target organisms. A great variety of PhACs, of generally low concentrations, and the complicated sample preparation, makes circumstantial the accurate detection and quantification. Additionally, there is little information published about the spatiotemporal variation of the PhAC load in a larger catchment area utilised for touristic purposes. In addition to the natural biotic and abiotic changes, the seasonal variation of tourism also has a dramatic impact on water quality and the natural ecosystem in larger catchment areas. Therefore, our aim was to develop a reliable solid-phase extraction (SPE)-supercritical fluid chromatography tandem mass spectrometry (SFC-MS/MS) method for simultaneous multi-residue analysis of drugs to reveal the spatiotemporal changes in the PhAC contaminations in the waters of an important touristic region, the catchment area of the largest shallow lake in Central Europe, Lake Balaton (Hungary). The environmental application of the developed method revealed 69 out of the traced 134 chemical compounds, including 15 PhACs, which were detected from natural waters for the first time. Wastewater treatment plant (WWTP) loads have a major role in the PhAC contamination of the studied area; at the same time, the mass tourism-induced PhAC contamination was also detectable. Furthermore, the impact of tourism was indicated by elevated concentrations of recreational substances (e.g., caffeine and illicit drugs) in the touristic season affecting the water quality of this important summer holiday destination.

Stereoselective environmental behavior and biological effect of the chiral organophosphorus insecticide isofenphos‑methyl

The enantiomeric environmental behaviors, bioactivities and toxicities of isofenphos‑methyl enantiomers were characterized systematically in this study. (R)‑Isofenphos‑methyl was degraded preferentially in Yangtze River water and different types of vegetables with an enantiomeric fraction (EF) of 0.6 to 0.96. However, (R)‑isofenphos‑methyl was amplified in both Nanjing (EF = 0.32) and Nanchang (EF = 0.27) soil. Our investigations found that there no bidirectional chiral inversion occurred in either Yangtze River water or soils. The bioactivity of (S)‑isofenphos‑methyl was higher than that of its (R)‑enantiomer against different insect targets, such as Meloidogyne incognita, Nilaparvata lugens, Plutella xylostella and Macrosiphum pisi (3.7 to 149 times). (S)‑Isofenphos‑methyl showed higher toxicity for the nontarget organism (1.1 to 32 times). However, (R)‑isofenphos‑methyl possesses 4.0 times more potency than the (S)-form for the nontarget soil organism Eisenia foetida. This study generally could provide more scientific guidance for the corresponding risk assessments of pesticides in addition to providing a new theoretical basis for scientifically and rationally using isofenphos‑methyl.

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.

Stereoselective Analysis and Dissipation of Propiconazole in Wheat, Grapes, and Soil by Supercritical Fluid Chromatography-Tandem Mass Spectrometry

An efficient and sensitive chiral analytical method was established for the determination of propiconazole stereoisomers by supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS). Stereoisomeric separation was performed on a Chiralpak AD-3 column with CO₂/ethanol (93:7) as the mobile phase. The four propiconazole stereoisomers were well separated in 4.7 min with resolutions above 2.0. The specificity, linearity, matrix effects, accuracy, precision, and stability of the developed method were evaluated. The stereoselective dissipation of propiconazole in wheat straw, grape, and soil samples was investigated according to the proposed method. The results indicated that significant stereoselective degradation occurred in wheat straw and grapes, with preferential degradation of (-)-propiconazole A and (+)-propiconazole B in wheat straw and the opposite case in grapes. No enantioselectivity was observed in soil, although diastereoisomer A degraded more rapidly than diastereoisomer B. These results could contribute to a more accurate assessment of the environmental risk and food safety of propiconazole.