The pesticide residue analysis in commodities with high content of chlorophyll based on the quick, easy, cheap, effective, rugged, and safe method: A review.

In multiresidue analysis, the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) is one of the most popular techniques routinely used by researchers during pesticide analysis of food and vegetable samples. Originally, the QuEChERS method was developed for analysis of pesticide residues from fruits and vegetables, but rapidly gained popularity in the extraction of analytes from different matrices. This analytical approach shows several advantages over traditional extraction techniques: it requires lower sample and solvent amounts while shortening the time of sample preparation. However, it presents some limitations for complex matrices such as those containing high amounts of chlorophyll. To overcome the problem of strong matrix effect and influence of interferences, different approaches are applied. Most are concerning modifications of the cleanup step, that is, sorbent type and its amount. Optimization of other parameters, such as sample size, hydration level, extraction solvent, and buffering, also has an impact on overall performance. Combining proper sample preparation with modern highly sensitive and selective detection techniques enables receiving desired limits of quantification. This article presents an overview of strategies employed by researchers for analysis of green, high chlorophyll content commodities and results obtained in their studies.

Smartphone-based molecularly imprinted sensors for rapid detection of thiamethoxam residues and applications.

In order to achieve rapid detection of thiamethoxam residues in mango, cowpea and water, this study modified the screen printed carbon electrode (SPCE) to make a specific molecular imprinting sensor (Thiamethoxam-MIP/Au/rGO/SPCE) for thiamethoxam. An integrated smartphone platform was also built for thiamethoxam residue analysis. The performance of the complete system was analyzed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The system was then applied for the rapid determination of thiamethoxam residues in water, mango and cowpea samples. The results showed that the molecular sensor showed good linearity in the range 0.5-3.0 µmol/L of thiamethoxam. The detection limit of thiamethoxam was 0.5 µmol/L. Moreover, the sensor had good reproducibility and anti-interference performance. The average recovery rates of the pesticide residues in water, mango and cowpea samples were in the range of 90-110% with relative standard deviations < 5%. The rapid detection system for thiamethoxam residue constructed in this study was simple, reliable, reproducible and had strong anti-interference. It has broad application prospects in the field detection of thiamethoxam residue, and serves as a valuable reference for the further development of rapid detection technology of pesticide residues in the field of environment and food safety.

Fatty Acid Analysis, Chemical Constituents, Biological Activity and Pesticide Residues Screening in Jordanian Propolis.

Propolis is a resinous natural product collected by honeybees (Apis mellifera and others) from tree exudates that has been widely used in folk medicine. The present study was carried out to investigate the fatty acid composition, chemical constituents, antioxidant, and xanthine oxidase (XO) inhibitory activity of Jordanian propolis, collected from Al-Ghour, Jordan. The hexane extract of Jordanian propolis contained different fatty acids, which are reported for the first time by using GC-FID. The HPLC was carried out to identify important chemical constituents such as fatty acids, polyphenols and α-tocopherol. The antioxidant and xanthine oxidase inhibitory activities were also monitored. The major fatty acid identified were palmitic acid (44.6%), oleic acid (18:1∆9cis, 24.6%), arachidic acid (7.4%), stearic acid (5.4%), linoleic acid (18:2∆9-12cis, 3.1%), caprylic acid (2.9%), lignoceric acid (2.6%), cis-11,14-eicosaldienoic acid (20:2∆11-14cis, 2.4%), palmitoleic acid (1.5%), cis-11-eicosenoic acid (1.2%), α-linolenic acid (18:3∆9-12-15cis, 1.1%), cis-13,16-docosadienoic acid (22:2∆13-16cis, 1.0%), along with other fatty acids. The major chemical constituents identified using gradient HPLC-PDA analysis were pinocembrin (2.82%), chrysin (1.83%), luteolin-7-O-glucoside (1.23%), caffeic acid (1.12%), caffeic acid phenethyl ester (CAPE, 0.79%), apigenin (0.54%), galangin (0.46%), and luteolin (0.30%); while the minor constituents were hesperidin, quercetin, rutin, and vanillic acid. The percentage of α-tocopherol was 2.01 µg/g of the lipid fraction of propolis. Antioxidant properties of the extracts were determined via DPPH radical scavenging. The DPPH radical scavenging activities (IC50) of different extracts ranged from 6.13 to 60.5 µg/mL compared to ascorbic acid (1.21 µg/mL). The xanthine oxidase inhibition (IC50) ranged from 75.11 to 250.74 µg/mL compared to allopurinol (0.38 µg/mL). The results indicate that the various flavonoids, phenolic compounds, α-tocopherol, and other constituents which are present in propolis are responsible for the antioxidant and xanthine oxidation inhibition activity. To evaluate the safety studies of propolis, the pesticide residues were also monitored by LC-MS-MS 4500 Q-Trap. Trace amounts of pesticide residue (ng/mL) were detected in the samples, which are far below the permissible limit as per international guidelines.

Residual characteristics of etofenprox in the processing stages of rice cakes and cookies.

The changes in residual amounts of an insecticide (etofenprox) in processed rice cakes and cookies were investigated in this study. Test samples were sprayed with etofenprox during rice cultivation, and brown rice samples were dipped in a pesticide solution to investigate the effects of washing and processing. A multiresidue method for multiclass pesticides was employed for etofenprox analysis using a high-performance liquid chromatography-ultraviolet detector setup. Etofenprox was not detected in polished rice that was processed into rice cakes and cookies. The etofenprox residue levels were 2.13 mg/kg in each processing stage of brown rice products that were dipped in 400 mg/kg etofenprox solutions. The residual amounts of etofenprox in washed/polished rice and rice flour obtained by grinding were 1.25 and 0.77 mg/kg, respectively. The residual levels were 0.38 mg/kg in rice cakes prepared by cooking rice flour in a steamer for 20 min (a decrease of 82.1% compared to that in polished rice), 0.47 mg/kg in rice cookies baked in an oven for 20 min (a decrease of 78.0%), and 0.21 mg/kg in fried rice cookies (a decrease of 90.2%). Overall, the residual levels of etofenprox decreased in a range of 40-100% during the processing of rice cakes and cookies.

[Hydrophilic interaction liquid chromatography for removal of pesticide residues in ginseng extracts].

Ginseng extracts are rich in a variety of ginseng monomer saponins, which have pharmacological functions of retarding aging, enhancing immunity, stimulating blood circulation, and lowering blood pressure. Ginseng is widely used in health products and dietary supplements in the domestic and foreign market. However, the amount of pesticide residues is an important index for measuring the quality of ginseng and ginseng extracts. Therefore, studies focused on methods for the removal of pesticide residues in ginseng extract are of great significance. Hydrophilic interaction liquid chromatography (HILIC) is used to improve the retention and separation selectivity of strongly polar substances, and it is widely employed in drug analysis, metabolomics, proteomics, etc. In this study, a method for the removal of pesticide residues was developed based on the difference in the retention behavior of pesticide residues and ginsenosides on the HILIC column. Using commercially available ginsenoside extracts, the retention behaviors of pesticide residues and ginsenosides on reverse chromatography and hydrophilic chromatographic columns were evaluated by high performance liquid chromatography. The results proved that on the reversed-phase liquid chromatography (RPLC) stationary phase, in addition to the strong retentions of quintozene and pentachloroaniline, which could be clearly separated from the saponins, the retentions of the other five pesticide residues including carbendazim, azoxystrobin, procymidone, iprodione and propiconazole were similar to total ginsenosides. The seven ginsenosides showed strong retention due to the formation of hydrogen bonds between the hydroxyl groups on the sugar chain and the carboxyl groups on the HILIC stationary phase. However, the pesticide residues were not well retained because of their poor hydrophilicity and small molecular weights. For this reason, the pesticide residues and ginsenosides could be completely separated on the HILIC column. Thus, enrichment of the seven ginsenosides and removal of the 14 pesticide residues was realized in one step on the HILIC column. In addition, the effects of loading amount, loading volume, and washing volume on the removal of pesticide residues in ginsenosides were investigated using the Click XIon SPE column. Then, taking the ginsenoside recoveries and pesticide residue removal rates into account, we confirmed the following: the ratio of the maximum sample loading mass to the filler mass was 1∶10; the optimal elution volume was twice the column volume; and the optimal loading volume was twice the column volume. The ginseng extracts were solvated with a 95% ethanol solution and loaded onto an HILIC column. The sample was subjected to pesticide residue removal, and ginsenoside purification and enrichment under the optimum removal conditions. Gradient elution was carried out using ethanol and water as the mobile phases. The total ginsenoside content in the final extracts was increased to 69.61%. The recovery of the total ginsenosides was 94.4%. The pesticide residues in the samples were quantitatively detected by gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) in the multiple reaction monitoring (MRM) mode. The 14 pesticide residues in the original ginsenoside extracts were effectively removed. The amounts of five residues were reduced to below 0.05 mg/kg, while the other nine residues were completely eliminated. This study demonstrates the application of HILIC to pesticide residue removal in traditional Chinese medicine extracts and reveals a new technique for the purification of natural products. The proposed method shows a high removal rate of pesticide residues and a high recovery of total ginsenosides. It is safe, efficient, and environment-friendly, and can aid the development of high-quality ginsenoside extracts.

A fluorinated chitosan-based QuEChERS method for simultaneous determination of 20 organophosphorus pesticide residues in ginseng using GC-MS/MS.

In this study, a new fluorinated methacrylamide (MACF) was synthesized and evaluated as an adsorbent in the dispersive solid-phase extraction for the effective determination and extraction of 20 organophosphorus pesticides (OPPs) from ginseng samples using the QuEChERS (quick, easy, cheap, effective, rugged, safe) method coupled with GC-MS/MS. The properties of MACF were characterized using Fourier-transform infrared spectroscopy, elemental analysis, and high-resolution 19 F NMR. MACF, chitosan, primary and secondary amine, octadecylsilane, graphitized carbon black, Z-Sep, Z-Sep+ , and EMR-Lipid were compared in terms of extraction efficiency. The best results were obtained when MACF was used. Matrix-matched calibration was employed for quantification. All the OPPs exhibited good linearity (r2 > 0.9969) with the concentration at their respective concentration ranges. The limits of detection were 1.5-3.0 µg/kg, and the limits of quantification were 5.0-10.0 µg/kg. The trueness of the 20 pesticides at four spiked levels ranged from 86.1 to 111.1%, and the relative standard deviation was less than 11.3%. The modified QuEChERS method using MACF as the adsorbent was sensitive, reliable, and cost-effective and could be used for the determination of 20 OPP residues in ginseng.

Evaluation of the automated micro-solid phase extraction clean-up system for the analysis of pesticide residues in cereals by gas chromatography-Orbitrap mass spectrometry.

Food analysis is a tremendously broad field that is constantly evolving. New methods have emerged to increase productivity, such as modern miniaturized and robotic analytical techniques. In this paper, a micro-solid-phase extraction system (µ-SPE) for clean-up was combined with a robotic autosampler to yield ready-to-analyze extracts. The system was evaluated for its applicability in routine laboratories. The new, automated, high-throughput µ-SPE clean-up method was applied to acetonitrile extracts and was developed for the analysis of pesticide residues in cereals by gas chromatography-Orbitrap mass spectrometry (GC-Orbitrap-MS). The µ-SPE clean-up efficiency was demonstrated in the removal of matrix-interfering components and in the recovery of pesticides. The sorbent bed mixture consisted of magnesium sulfate, primary-secondary amine, C18, and CarbonX, and effectively retained matrix components without loss of target analytes. Analysis of five types of cereals (barley, oat, rice, rye, and wheat) by GC-Orbitrap-MS showed that the method removed more than 70% of matrix components. The clean-up method was validated for 170 pesticides in rye, 159 pesticides in wheat, 142 pesticides in barley, 130 pesticides in oat, and 127 pesticides in rice. Spike recovery values were 70-120% for all pesticides and the repeatability, calculated as the relative standard deviation, was less than 20%. The limits of quantitation achieved were 0.005 mg kg-1 for almost all analytes, ensuring compliance with the maximum residue limits.

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.

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%.

Zeolitic imidazolate framework-8 decorated with gold nanoparticles for solid-phase extraction of neonicotinoids in agricultural samples.

A composite built with aminated zeolitic imidazolate framework and gold nanoparticles (AuNPs) for solid-phase extraction (SPE) of neonicotinoids in agricultural samples is presented. The composite was prepared through the assembly of AuNPs onto the surface of metal-organic framework based on the strong interaction between the amino group and AuNP. These metallic surfaces provided additional interactions based on the affinity of amino and cyano groups present in the target compounds. The composite was characterized by scanning electron microscopy, powder X-ray diffraction, Fourier-transform infrared spectroscopy, and surface area measurements. Regarding the SPE protocol, several parameters that can influence the extraction performance were optimized, such as sample volume or composition of elution solvent, among others. After elution, the analytes were determined via HPLC with diode-array detection. Under the selected conditions, satisfactory recoveries of five pesticides (thiamethoxan, clothianidin, imidacloprid, acetamiprid, and thiacloprid) were obtained (between 80 and 110%) in real samples, whereas the limits of detection ranged from 0.019 to 0.041 µg L-1 in aqueous samples and 0.3 to 0.8 µg g-1 in solid samples.

In-syringe temperature-controlled liquid-liquid microextraction based on solidified floating ionic liquid for the simultaneous determination of triazine and phenylurea pesticide in vegetable protein drinks.

A novel in-syringe temperature-controlled liquid-liquid microextraction based on solidified floating ionic liquid (in-syringe TC-LLME-SFIL) combined with high performance liquid chromatography was developed for the simultaneous determination of monuron, chlorotoluron, atrazine, monolinuron, propazine and prometryn in commercial vegetable protein drinks. The samples were deproteinized by trichloroacetic acid and further cleaned up by solid phase extraction column. The ionic liquid tributyldodecylphosphonium tetrafluoroborate ([P4 4 4 12]BF4) was used as extraction solvent and dispersed into the depurated sample solution to form fine droplets with the assistance of heating and vortex. With the help of an ice bath, the ionic liquid phase solidified and floated on the surface of aqueous phase. After separation from the aqueous phase, the solidified ionic liquids were dissolved with acetonitrile and the resulting solution was analyzed by high performance liquid chromatography. Some extraction parameters, including type and amount of adsorbent, type and amount of ionic liquids, amount of NaCl, melting temperature and time of ionic liquid, vortex time, pH of sample solution, ice bath temperature and time, were investigated and optimized by single-factor experiment, Plackett-Burman design and Box-Behnken design. The results showed that good linearities (r ≥ 0.9994) were obtained in the concentration range of 7.8-1000.0 µg/L. The limits of detection and quantification were in the range of 0.25-2.59 µg/L and 0.82-8.63 µg/L, respectively. The spiked recoveries were 81.26-118.42% with the relative standard deviation (RSD, n = 3) lower than 8.17%. The present method was successfully applied to the simultaneous determination of triazine and phenylurea herbicides in vegetable protein drinks.

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%.

The present situation of pesticide residues in China and their removal and transformation during food processing.

Pesticide residues are one of the most important issues affecting food safety. In this review, the general situation of pesticide residues in fruits and vegetables based on the background of the Chinese fruit and vegetable industry is first described. On the basis of primary processing of agricultural products, the effects of processing methods on the removal and metabolism of pesticide residues are reviewed in this paper. In addition, the transformation mechanism of pesticides in crops and in the environment is discussed. Finally, this study summarizes the development trend of pesticide-residue monitoring methods. With the prohibition of a large number of pesticides in China, the risk of pesticide residues is gradually reduced. However, some highly toxic pesticides can still be detected. Furthermore, the development of high-resolution mass spectrometry screening methods and rapid and intelligent detection instruments is the development trend for pesticide monitoring in the future.

Pesticides and their metabolites in human urine: development of multi-analyte method by LC-MS/MS and GC-MS/MS.

The objective of this study consists of being able to develop a precise, reliable, easy, cheap and quick method to identify and quantify the presence of pesticide metabolites and their parents in human urine. In order to reach our purpose we selected the pesticides and their metabolites with intended uses on permanent crops such as orchards and vineyard. The activity planning started with the identification of the target list carried out by UHPLC-MS/MS and GC-MS/MS, succeeded by several tests oriented to determine the best sample treatment having recourse to instrumental analysis in the range 5-100 ng/mL. Several purifications were also investigated combining different adsorbents (PSA, EMR-lipid and final polish pouch). The use of formic acid during the extraction step has no impact on the recoveries, whereas the PSA adsorbent in the cleanup step negatively affects the results for all investigated metabolites. Any substantial differences were not observed in urine matrix for parent compounds achieving recoveries higher than 80% and RSD less than 20%. The final polish in combination or not with Enhanced Matrix Removal EMR-lipid did not show statistically significant difference in term of trueness and precision for both metabolites and parents, as evaluated by one-way ANOVA. The 3-OH THPI was the most critical compound with not acceptable results for linearity, trueness and precision.

Preparation of magnetic MOFs for use as a solid-phase extraction absorbent for rapid adsorption of triazole pesticide residues in fruits juices and vegetables.

Detection of low levels of triazole fungicides in agricultural product matrices is important. Although several detection methods have been developed, all have some drawbacks, such as being time-consuming, requiring complex sample pretreatment, and consuming large volumes of organic solvents. There is an urgent need for a simple and rapid detection method for triazole fungicides. In this study, the adsorbent composite material magnetic MOFs based on Fe3O4-MWCNT was synthesized by in-situ polymerization at room temperature, and was applied to extract triazole pesticides from fruits and vegetables. High-performance liquid chromatography-tandem mass spectrometry was used for quantification. Under optimized conditions, the constructed detection method showed a low detection (LOD) of 0.52-1.83 µg/L (S/N = 3) and wide linear range of 5.00-500.00 µg/L for triazole fungicides in the fruit and vegetable samples. The method recovery for spiked fungicides (10, 50, and 100 µg/L) in cabbage, spinach, orange juice, and apple juice ranged from 62.80% to 94.20%. The constructed detection method has a lower detection limit than previously reported methods and has a higher sensitivity for triazole pesticide residues in complex matrices.

Determination of organophosphorus and synthetic pyrethroid pesticide residues and their variability in large size fruit crops.

BACKGROUND: Variability of pesticide residues in food item plays a key role for the evaluation of consumer food safety. However, variability factors (VFs) derived from the large size fruit crops are still scarce. Therefore, the present work was aimed to quantify pesticide residues and to estimate VFs in large size fruit crops of mango and guava. RESULTS: A total of 140 mango and 130 guava samples from different marketplaces in Bangladesh were collected to estimate the variability of pesticide residues (acephate, diazinon, malathion, fenitrothion, chlorpyrifos, quinalphos, dimethoate and cypermethrin) by in-house validated methods based on modified QuEChERS extraction and gas chromatography coupled with electron capture detector (ECD) and flame thermionic detector (FTD). The method was validated at three fortification levels (0.01, 0.10 and 0.30 mg kg-1 ) and satisfactory recoveries (80-111%) with relative standard deviation (RSDr ) ≤ 13% were achieved. A wide variation of residues was found in the analyzed samples. In the case of mango, the ranges of residues were 0.011-0.314, 0.015-0.04, and 0.05-0.291 mg kg-1 , respectively, for cypermethrin, chlorpyrifos, and dimethoate, while in the case of guava, the ranges were 0.04-0.113, and 0.03-0.290 mg kg-1 , respectively, for cypermethrin and acephate. The average VF for mango was 4.06 and it was 5.70 for guava. CONCLUSION: VFs originating from the marketed samples of mango and guava are reported in this study for the first time. The estimated VFs were higher than the default value of 3, therefore, the default VFs should be reconsidered when more data are obtained regarding large size crops. © 2021 Society of Chemical Industry.

Magnetic metal-organic framework MIL-100 (Fe)/polyethyleneimine composite as an adsorbent for the magnetic solid-phase extraction of fungicides and their determination using HPLC-UV.

Fe3O4@MIL-100 (Fe)/PEI are used for the first time as an adsorbent material for the extraction of pesticide residues (epoxiconazole, flusilazole, tebuconazole, and triadimefon) from food matrices. The adsorbent proposed (Fe3O4@MIL-100(Fe)/PEI) was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), thermogravimetric (TG) analysis, and vibrating sample magnetometer (VSM) techniques to evaluate the properties of the sorbent. Then, the Fe3O4@MIL-100 (Fe)/PEI was employed for the quantification of the four triazole fungicides in fruits and vegetables (apple, orange, tomato, cabbage, and cucumber) using HPLC-UV for separation and detection. During the extraction process, the main parameters such as amount of adsorbent, extraction time, pH value, ionic strength, eluting solvent, and eluting volume were optimized. Under the optimum conditions, good linearity of this method was observed for all analytes, with correlation coefficients (R2) ≥ 0.9908. The limits of detection (LODs) ranged from 0.021-3.04 µg kg-1. The extraction recoveries of the four triazole fungicides varied from 73.9 to 109.4% with relative standard deviations (RSD) in the range 0.5 to 6.2%. Compared with other MOFs, the modification of Fe3O4@MIL-100 (Fe) with PEI shows high efficient adsorption due to the combined benefits of MIL-100 (Fe) and PEI. The material is easily synthesized, has good stability, and is of low cost.  Graphical abstract.

Fe3O4 nanoparticles as matrix solid-phase dispersion extraction adsorbents for the analysis of thirty pesticides in vegetables by ultrahigh-performance liquid chromatography-tandem mass spectrometry.

Herein we report the first example of Fe3O4 nanoparticles (FNPs) being used as single-matrix solid-phase dispersion (MSPD) adsorbents for the extraction of 30 representative pesticides from vegetables. This study was aimed at analyzing the extracted samples using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Various condition parameters, such as the eluent, volume of the eluent, and amount of FNPs were optimized to achieve good sensitivity and precision for the elution and extraction of the analytes. The developed method was validated using matrices consisting of eight vegetables (lettuce, cucumber, carrot, tomato, pepper, shallot, Chinese flowering cabbage, and cabbage) spiked with 30 pesticides at concentrations of 0.01, 0.1, and 1.0 mg/kg. The recoveries of the 30 pesticides (organophosphorus, triazole, carbamate, nicotine, amide, and other different structures of pesticides) were in the range 71.0-110.8% (n = 5) (except those of prothioconazole and dinotefuran), with relative standard deviations lower than 13.5% in all the matrices under optimal conditions. The matrix effects were observed by comparing the slope of the matrix-matched standard calibration curve with that of the solvent. However, the matrix effects of the eight vegetables did not show evident regularities. For pepper, tomato, and shallot, a sizable number of pesticides (24, 21, and 21, respectively) showed suppressive matrix effects. On the other hand, for cucumber, Chinese flowering cabbage, and cabbage, a good number of pesticides (19, 18, and 15, respectively) showed negligible matrix effects. Furthermore, for carrot matrices, 21 pesticides showed a matrix enhancement effect. Excellent linearity was achieved at pesticide concentrations of 0.01-1.0 mg/L, and the limits of quantification (LOQ) for the developed method reached 0.01 mg/kg (except that for dinotefuran, which was 0.1 mg/kg), based on the spiked test. The developed method was successfully employed in the analysis of real samples in Nanning, China, and three pesticide residues (halosulfuron methyl, tebuconazole, and azoxystrobin) were commonly detected in vegetable samples. In the present study, a reliable method-validation performance and excellent cleanup effects were observed by using the modified MSPD method consisting of the FNPs in the cleanup step.

Room-temperature synthesis of magnetic covalent organic frameworks for analyzing trace benzoylurea insecticide residue in tea beverages.

A novel magnetic covalent organic framework (NH2-Fe3O4@COF) was prepared using a simple room-temperature synthesis in this study. These magnetic particles exhibited high adsorption performance with short adsorption time (10 min) for six benzoylurea insecticides (BUs) as magnetic solid-phase extraction (MSPE) adsorbents. Quantum chemistry calculation demonstrated that adsorption mechanism was primarily attributed to strong halogen bonds between electronegative O atoms of COF and electropositive F atoms of BUs as well as potential hydrophobic effect. Wide linearities (10-1000 ng·L-1) and low limits of detection (0.06-1.65 ng·L-1) for six analytes were obtained via liquid chromatography-tandem mass spectrometry. Applicability of the proposed method was further evaluated by analyzing four kinds of original tea beverages. Recoveries of six BUs in spiked samples ranged from 80.1% to 108.4%.

Overview of Analytical Methods for the Determination of Neonicotinoid Pesticides in Honeybee Products and Honeybee.

Neonicotinoid pesticides are widely applied for controlling pests in a variety of agriculture crops. Due to the systemic distribution in plants, neonicotinoid pesticides have been found in nectar and pollen, which are the main source of food for the important pollinator honeybee. The risk of neonicotinoid residues in honeybee products and honeybee has caused great attention since their impacts on the environment, ecology, and food safety issues. These concerns require the accurate and sensitive determination of neonicotinoids and their metabolites in the honeybee products and honeybee. Since the trace residue level of neonicotinoid and the complexity of the samples, analysis of neonicotinoid targets in these important matrices is still a great challenge. The present review provides general overview of analytical methods for the determination of neonicotinoid pesticides and their metabolites in honeybee products and honeybee.