Multiresidue analysis of over 200 pesticides in cereals using a QuEChERS and gas chromatography–tandem mass spectrometry-based method

Development of a highly sensitive method based on QuEChERS and GC-MS/MS for the determination of polycyclic aromatic hydrocarbons in infant foods

Polycyclic aromatic hydrocarbons (PAHs) are environmental contaminants that can be found in various food products, including those intended for infants. Due to their potential health risks, it is crucial to develop sensitive analytical methods for the accurate determination of PAHs in infant foods. This study describes the development and validation of a highly sensitive method for the quantification of European PAH markers, namely benzo[a]pyrene, benzo[a]anthracene, chrysene, and benzo[b]fluoranthene, using gas chromatography-tandem mass spectrometry (GC-MS/MS), in baby food samples. The first step was the optimization of the sample preparation procedure, performed using different methods based on the QuEChERS approach, also testing different extraction solvents. Several factors such as extraction efficiency, selectivity, and recovery were evaluated to choose the most effective procedure for sample preparation. Furthermore, the GC-MS/MS method was optimized, evaluating parameters such as linearity, sensitivity, accuracy, and robustness using spiked infant food samples. The method demonstrated excellent linearities with a correlation coefficient higher than 0.999 over a wide concentration range, and limits of detection and limits of quantification in the range 0.019-0.036 μg/kg and 0.06-0.11 μg/kg, respectively. Extraction recoveries were between 73.1 and 110.7%, with relative standard deviations always lower than 8%. These findings are compliant with the indications of the European Commission (Reg. 836/2011). To assess the applicability of the method to official control activities, a survey was conducted on commercially available infant food products. Four markers were determined in commercial samples belonging to different food categories for infants and young children. The outcome of this monitoring showed that PAH contamination, in all samples, was below the quantification limits. In conclusion, the developed GC-MS/MS method provides a highly sensitive and reliable approach for the determination of PAHs in baby foods. The optimized sample preparation, instrumental parameters, and validation results ensure accurate quantification of 4 PAHs even at trace levels. This method could contribute to the assessment of PAH exposure in infants and it could support regulatory efforts to ensure the safety and quality of infant food products with regular monitoring.

Dissipation behavior, residue distribution, and exposure risk assessment of tebufenpyrad and milbemectin acaricides in strawberries under open field conditions

Strawberries are a favorite fruit for most people, but the residues of pesticides on strawberries might be risky to human health. Tebufenpyrad and milbemectin are broad-spectrum acaricides with insecticide properties authorized for use on strawberries in Egypt. As a result, it is crucial to investigate their residues in the final product to ensure customers' safety. Consequently, field trials were conducted following the Good Agricultural Practices (GAPs) to study the dissipation rate and terminal residues of tebufenpyrad and milbemectin on strawberries. Tebufenpyrad and milbemectin residues in strawberries declined due to first-order decay process, showing significant degradation (88.5% and 94.7%, respectively) after 14 days. Risk assessment study was carried out by comparing the national estimated daily intake (NEDI) to the acceptable daily intake (ADI). The results demonstrated that the dietary risk posed by the residues of tebufenpyrad and milbemectin in strawberry fruits was acceptable for consumers. It is envisaged that the current study's findings would support the safe application of tebufenpyrad and milbemectin to strawberries and perhaps other crops in Egypt and other countries with similar climatic conditions.

Residue behaviors of six pesticides during apple juice production and storage

The residue behaviors of carbendazim, thiamethoxam, imidacloprid, acetamiprid, prochloraz, and difenoconazole during the production and accelerated storage of apple clear and cloudy juice was systemically evaluated. The pesticides were determined by liquid chromatography-mass spectrometry (LC-MS/MS) after each processing step and at different storage times. The results indicated that the different processing steps in the apple clear and cloudy juices production have different effects on the reduction of pesticide residues. The pre-processing steps including washing and pressing reduced the pesticide residues significantly by 36.8 % to 67.9 % and 32.9 % to 89.8 %, respectively, mainly due to the water solubility and log Kow of pesticides. The enzymation step in clear juice production slightly reduced six pesticide residues from 1.9 % to 31.6 %, and the filtration step after clarification and purification decreased the pesticide residues from 14.0 % to 87.5 % with no significance, while prochloraz was not detected. The centrifugation step in cloudy juice production reduced the pesticide residues from 6.3 % to 88.9 %. The pasteurization step in clear and cloudy juice production lowered the pesticide residues slightly on account of the short heating time of 30 s. The accelerated storage of clear and cloudy juices was effective in the reduction of pesticide residue levels. The processing factors (PFs) in the whole process of clear and cloudy juice production were equal to or lower than 0.2, especially for prochloraz and difenoconazole, illustrating that apple juice production could decrease the pesticide residues greatly. The results will provide important references to predict the levels of pesticide residues in apple juice during processing and storage. Meanwhile, the PFs identified in the study could be helpful in the risk assessment of pesticides in apple juice.

Development of an enhanced analytical method utilizing pepper matrix as an analyte protectant for sensitive GC‒MS/MS detection of dimethipin in animal-based food products

Herein, an analytical method using gas chromatography-tandem mass spectrometry (GC‒MS/MS) was devised to detect the presence of the troublesome pesticide dimethipin in various animal-based food products, including chicken, pork, beef, eggs, and milk. The injection port was primed with a matrix derived from pepper leaves that acts as an analyte protectant (AP) to safeguard the target compound from thermal degradation during gas chromatography. The presence of AP resulted in a remarkable limit of quantification of 0.005 mg/kg for dimethipin in five matrices. Three different versions (original, EN, and AOAC) of the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method were compared for dimethipin extraction, with a double-layer solid-phase extraction (SPE) cartridge utilized for matrix purification. A seven-point external calibration curve was established for dimethipin in the five matrices, demonstrating excellent linearity with determination coefficients (R2) ≥ 0.998. The developed quantitative method was validated by fortifying each matrix with three different concentrations of standard dimethipin, and the average recovery fell within the acceptable range outlined in the CODEX guidelines (ranging from 88.8% to 110.0%), with a relative standard deviation (RSD) of ≤ 11.97%. This method effectively addresses the challenge of analyzing dimethipin and can therefore be used as a routine monitoring tool for dimethipin across various matrices.

Simultaneous Determination of 54 Pesticides in Proso Millet Using QuEChERS with Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

To assess the potential risks posed to the environment and human health, analyzing pesticide residues in proso millet is important. This paper aimed to develop a modified QuEChERS method with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the analysis of 54 pesticide residues in proso millet. Parameters including the mobile phase of the instrument, the acidity of the extraction solvent, and the type of absorbents were optimized to provide satisfactory performance. The method was validated concerning linearity, limit of quantification (LOQ), matrix effect, accuracy, and precision. In detail, the linearity of the matrix-matched calibration curve was acceptable with correlation coefficients (R2) higher than 0.99. The mean recovery was in the range of 86% to 114% with relative standard deviations (RSDs) ≤ 20% (n = 5). The LOQ was determined to be 0.25-10 μg/kg. The developed method was feasible for the determination of multiple pesticide residues in proso millet.

Dissipation, Bioconcentration and Dietary Risk Assessment of Thiamethoxam and Its Metabolites in Agaricus bisporus and Substrates under Different Application Methods

In order to acquire scientific evidence for the application of thiamethoxam (TMX) in Agaricus bisporus cultivation, residue and dissipation experiments for field trials were performed with the application of TMX in compost and casing soil, respectively. An effective QuEChERS method was established to analyze TMX and its two metabolites, clothianidin (CLO) and thiamethoxam-urea (TMX-urea), in compost, casing soil, and fruiting bodies. The results indicated that the TMX dissipation half-lives (t_1/2) at dosages of 10 and 50 mg kg^-1 were 19.74 d (day) and 28.87 d in compost and 33.54 d and 42.59 d in casing soil, individually. TMX, CLO, and TMX-urea were observed after TMX application in compost and casing soil. For TMX applied to the casing soil, only TMX residues were detected in fruiting bodies with bioconcentration factors (BCFs) of 0.0003~0.0009. In addition, both the chronic risk quotient (RQ) and acute risk quotient (HQ) values of TMX in fruiting bodies were far less than 1, which means the dietary health risks to humans were acceptable. However, in the TMX application to the compost, these analytes were not detected in the fruiting bodies. This suggested that the application of TMX in compost was safer than in casing soil during A. bisporus cultivation.

Multi-Residue Screening of Pesticides in Aquatic Products Using High-Performance Liquid Chromatography-Tandem High-Resolution Mass Spectrometry

Pesticide residues in aquatic products are of great concern due to the risk of environmental transmission and their extensive use in aquaculture. In our work, a quick screening approach was developed for the qualitative and semi-quantitative screening of 87 pesticide residues in aquatic products. The sample preparation was investigated, including extract solvent, extract methods, buffer salts, lipid removal, cleanup materials and filter membranes for aquatic products. Samples were extracted using a modified QuEChERS procedure, and two clean-up procedures were developed for UHPLC-Q/Orbitrap MS analysis based on the fat content of the aquatic products. The screening detection limits for all studied pesticides were distributed between 1 and 500 μg/kg in the three representative matrices. Seventy-one pesticides could be analyzed with a screening limit between 1 and 25 μg/kg in grass carp and crayfish, sixty-one pesticides could be screened for limits between 1 and 50 μg/kg in crab. The accuracy results showed that recoveries ranged from 50 to 120% for 60, 56 and 52 pesticides at medium-level for grass carp, crayfish and crab, respectively. At high spiking levels, 74, 65 and 59 pesticides were recovered within the range of 50-120% for the three matrices, respectively. The relative standard deviations of most compounds in different matrices were less than 20%. With this method, the local farmed aquatic products were tested for pesticide residues. In these samples, ethoxyquinoline, prometryn and phoxim were frequently detected. The majority of these confirmed compounds did not exceed 2.00 μg/kg. A grass carp with trichlorfon at 4.87 μg/kg and two carps with ethoxyquinoline at 200 µg/kg were detected, indicating the potential dietary risk.

Rapid Analysis of Residues of 186 Pesticides in Hawk Tea Using Modified QuEChERS Coupled with Gas Chromatography Tandem Mass Spectrometry

In this work, the QuEChERS method was modified and evaluated for the determination of 186 pesticides from caffeine-free and fatty hawk tea prior to their gas chromatography tandem mass spectrometry analysis for the first time. The results showed that the combination of MgSO₄ + PSA + MWCNTs plus EMR-Lipid provided the lowest matrix effect and best recovery; 117 of 186 pesticides manifested weak matrix effects. Thus, for accurate quantification, it is necessary to use matrix-matched calibration curves to compensate for the matrix effect. At the spiked level of 0.1 mg/kg, the average recoveries of 184 pesticides were in the range of 70-120% and the RSDs were 0.3-14.4% by the modified method. Good linearity was shown for 186 analytes at concentration of 0.01 mg/L~0.4 mg/L, and the correlation coefficients exceeded 0.99 for 182 pesticides. The detection limits of 186 pesticides by the modified QuEChERS method were 0.001-0.02 mg/kg, and the limits of quantification (LOQ) were 0.005 mg/kg~0.05 mg/kg. The necessity of solvent exchange is also explained in this work. The successful application of the modified QuEChERS in real samples proved that this method could be one of the routine options for analysis of herbal tea.

Simultaneous determination of succinate-dehydrogenase-inhibitor fungicide traces in cereals by QuEChERS preparation and UPLC-MS/MS analysis

A method for the simultaneous determination of 19 succinate dehydrogenase inhibitor (SDHI) fungicide residues in 8 kinds of cereals was established by combining UHPLC-MS/MS with the improved QuEChERS method. MgSO₄ and octadecylsilane (C₁₈) were used as the dispersive-solid phase extraction sorbent. The proposed method had good linearity in the range of 10-100 µg/L with correlation coefficients (R² > 0.99). The limit of quantification of 19 fungicides was 10 µg/L, which is the minimum addition level of the method. The fortified recoveries of 19 SDHI fungicides at three levels were ranged from 79.57 % to 126.25 %. The developed method was utilized for the analysis of 45 real cereal samples, only 5 samples were detected with SDHI fungicides. The contents of the fungicides detected in the real samples are far lower than the MRL. The results indicated that the proposed method is reliable for detecting SDHI fungicides in cereals.

Biscuit Contaminants, Their Sources and Mitigation Strategies: A Review

The scientific literature is rich in investigations on the presence of various contaminants in biscuits, and of articles aimed at proposing innovative solutions for their control and prevention. However, the relevant information remains fragmented. Therefore, the objective of this work was to review the current state of the scientific literature on the possible contaminants of biscuits, considering physical, chemical, and biological hazards, and making a critical analysis of the solutions to reduce such contaminations. The raw materials are primary contributors of a wide series of contaminants. The successive processing steps and machinery must be monitored as well, because if they cannot improve the initial safety condition, they could worsen it. The most effective mitigation strategies involve product reformulation, and the use of alternative baking technologies to minimize the thermal load. Low oxygen permeable packaging materials (avoiding direct contact with recycled ones), and reformulation are effective for limiting the increase of contaminations during biscuit storage. Continuous monitoring of raw materials, intermediates, finished products, and processing conditions are therefore essential not only to meet current regulatory restrictions but also to achieve the aim of banning dietary contaminants and coping with related diseases.

Easy and effective analytical method of carbendazim, dimethomorph, and fenoxanil from Protaetia brevitarsis seulensis using LC-MS/MS

Traditionally in Korea, Protaetia brevitarsis seulensis (white-spotted flower chafer) has been used as a medicine, and recently has attracted increased attention due to its antithrombotic efficacy. Some of spent mushroom compost or fermented oak sawdust, a feedstock for P. brevitarsis, were contaminated with three fungicides, carbendazim, dimethomorph, and fenoxanil, which could be transferred to the insect. This study was aimed to optimize a simple extraction method combined with liquid chromatography tandem mass spectrometry and apply it to the real samples. After the pulverized samples (5 g) were extracted with acetonitrile (10 mL) and formic acid (100 μL), fat and lipids in the samples were slowly precipitated at -20°C for 24 hours. After eight different clean-up methods were investigated, the mixture of 150 mg MgSO₄/25 mg PSA/25 mg C18 was selected due to optimal recovery of the target compounds. Recovery (77.9%‒80.8% for carbendazim, 111.2%‒116.7% for dimethomorph, and 111.9%‒112.5% for fenoxanil) was achieved with reasonable relative standard deviation (<5.5%) The analytical method developed in this study was used to analyze three compounds in the 24 insect samples donated by the insect farm owners but no target compounds were detected. These results can provide important data for establishing the pesticide safety standards for P. brevitarsis before the medical applications.

Simultaneous Detection of Multiple Plant Growth Regulator Residues in Cabbage and Grape Using an Optimal QuEChERS Sample Preparation and UHPLC-MS/MS Method

BACKGROUND

At present, PGRs are widely used in agricultural and forestry production in the world, PGRs, like the traditional pesticides have certain toxicity, naively excessive applied them will cause the acute and chronic poisoning of humans and animals, potential harm to human health.

OBJECTIVES

In order to assess, prevent and control the residues of plant growth regulators (PGRs) in fruits and vegetables, a set of easy, sensitive, quick, cheap, effective, reliable and safe analytical method that simultaneously detects multiple PGRs residues is urgently needed for the inspection departments of agricultural product's quality safety.

METHODS

In this study, grape (representative of fruit) and cabbage (representative of vegetable) were used as the detected objects. The 30 commercial products residues of PGRs in both were detected with the ultra-high performance liquid chromatography-tandem mass spectrometric (UHPLC-MS/MS) method based on the optimized chromatographic conditions, mass spectrometry and preparation conditions (extraction solvent and cleanup conditions). Grape and cabbage samples were extracted by acetonitrile containing 5% (v/v) acetic acid, dehydrated by salt package, purified by QuEChERS method, ionized by electrospray (ESI) under positive and negative ion switching mode, detected by multi-reactions monitoring (MRM) and quantification by external standard method of matrix matching standard curve.

RESULTS

The results showed that methanol was selected as the strong elution phase. The methanol-0.1% formic acid-5 mmol/L ammonium acetate solution was selected as the best mobile phase. The optimal extraction solvent was acetonitrile containing 5% acetic acid. PSA cleanup could meet the determination requirements of PGRs residues. The developed method for 30 commercial products of PGRs such as betaine showed excellent linearity in 1∼500 μg/kg, 10∼1000 μg/kg, ∼500 μg/kg, ∼2000 μg/kg, and 100∼10000 μg/kg (R ≥ 0.98). At the 0.001 mg/kg (0.01 mg/kg), 0.05 mg/kg, 0.20 mg/kg and 1.00 mg/kg additive concentrations, the average addition standard recovery of 30 commercial products of PGRs were 61%∼132% with the relative standard deviations (RSD) of 1%∼14%, the LOQwere confirmed 1.0-100 μg/kg through the actual addition values of samples.

CONCLUSIONS

The results demonstrated that the optimized "QuEChERS-UHPLC-MS/MS method" is a set of simple, rapid, sensitive, accurate, efficient, economical and safe detection method that simultaneously detected the residues of more PGRs in fruits and vegetables through one time sample preparation for their high-throughput rapid quantitative screening and confirmation; it is characterized by wide coverage of detecting PGRs types, simple and convenient preparation and small amount of solvent, and which can provide the technical supports for the supervision of PGRs residues in fruits and vegetables.

HIGHLIGHTS

Based on the facts mentioned above, the optimizations of extraction solvent screening, different ratio of various purification packings in QuEChERS method and UPLC-MS conditions were conducted and the indexes of method such as precision, sensitivity and recovery rate were investigated in order to establish an simple, quick, sensitive, cheap, efficient, reliable and safe QuEChERS-UPLC-MS/MS method for simultaneously detecting the 30 kinds of PGRs residues in fruits and vegetables a set of method with simultaneously detecting 30 kinds of PGRs; which shall meet the high throughput determination of multiple PGRs residues in fruits and vegetables and can also provide the technical references for related compounds residues detection of other matrix.

Effective and rugged analysis of glyphosate, glufosinate, and metabolites in Tenebrio molitor larva (mealworms) using liquid chromatography tandem mass spectrometry

Tenebrio molitor larva (mealworms) has recently attracted attention as a protein source for food and feed. The larva is generally fed with wheat bran, which can be possibly contaminated with glyphosate. To establish food safe standards, a rugged and effective analytical method for glyphosate, aminomethylphosphonic acid, glufosinate, and their metabolites including 3-methylphosphinico-propionic acid, and N-acetyl glufosinate, in mealworms was optimized using liquid chromatography tandem mass spectrometry. An anionic polar pesticide column was used due to its high suitability for glyphosate. Acidified water and acetonitrile were used to extract the target compounds without contribution from various fatty and pigment interferences derived from brownish insects. Seven different clean-up procedures ((1) 50 mg C18 (2) 20 mg C18/Z-sep (3) PRiME hydrophilic-lipophilic balance (HLB) cartridge (4) 75 mg Z-sep, (5) 75 mg Z-sep+, (6) EMR-lipid cartridge, and (7) 50 mg ENVI-Carb) were compared. Due to its simplicity and cost-effectiveness, PRiME HLB was selected for clean-up. The recoveries of the target compounds were ranged from 86 to 96% with < 20% relative standard deviations. Therefore, this simple and effective method can be applied for the two pesticides and their metabolites in other edible insects or high-fat matrices.

Nontarget and high-throughput screening of pesticides and metabolites residues in tea using ultra-high-performance liquid chromatography and quadrupole-orbitrap high-resolution mass spectrometry

A Sin-QuEChERS, coupled to UHPLC Q-Exactive Orbitrap MS, was used for nontargeted high-throughput rapid screening and quantitative analysis of residual pesticides and metabolites in green teas. The sample was extracted with 0.1% formic acid in acetonitrile with shaking, salted out and centrifuged, and purified with Sin-QuEChERS Nano solid phase extraction column; with Full MS/ddMS2 as the data collection mode, the database containing 384 pesticides combined with Trace Finder 3.0 software, In the absence of standard products, rapid screening and confirmation of potential pesticide residues in tea samples with accurate mass, isotope abundance ratio, secondary fragment ions, etc. 20 pesticides were used as quality controls to verify the screening method, and the linearity of these pesticides was between 1 and 200 μg/L, and the correlation coefficients were all greater than 0.9922. Moreover, the LOQ was between 0.002 and 0.01 mg/kg. The average recoveries of spiked tea samples were 74%-111%. Efficiency and reliability of this method were investigated by the analysis of 38 Chinese green tea samples. 18 potential residual pesticides were detected by non-targeted screening. The researchers then conducted a quantitative analysis of the 18 potential residual pesticides.

Rapid Screening of 350 Pesticide Residues in Vegetable and Fruit Juices by Multi-Plug Filtration Cleanup Method Combined with Gas Chromatography-Electrostatic Field Orbitrap High Resolution Mass Spectrometry

A new method for screening pesticide residues in vegetable and fruit juices by the multi-plug filtration cleanup (m-PFC) method combined with gas chromatography-electrostatic field orbitrap high resolution mass spectrometry(GC-Orbitrap/MS) was developed. The samples were extracted with acetonitrile, purified with m-PFC and determined by GC-Orbitrap/MS. Qualitative analysis was confirmed by retention time, accurate molecular mass and quantitative analysis were performed with the matrix standard calibration. It could eliminate matrix interference effectively. Eight kinds of typical samples (orange juice, apple juice, grape juice, strawberry juice, celery juice, carrot juice, cucumber juice, tomato juice) were evaluated. The linear ranges of the 350 pesticides were from 5 to 500 μg/kg, with good correlation coefficients greater than 0.990. The limits of detection (LODs) were 0.3-3.0 μg/kg and the limits of quantification (LOQs) were 1.0-10.0 μg/kg. The average recoveries at three spiked levels of 10, 100, 200 μg/kg were in the range of 72.8-122.4%, with relative standard deviations (RSDs) of 2.0-10.8%. The method has effectively improved the determination efficiency of pesticide residue screening by high-resolution mass spectrometry in vegetable and fruit juices.

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.

Determination of cyflufenamid residues in 12 foodstuffs by QuEChERS-HPLC-MS/MS

Agricultural products are often contaminated with trace amounts of pesticide residues. To ensure food safety, a reliable, sensitive, and efficient method that accurately identifies pesticide residues in a wide variety of foodstuffs is needed. This study applied a modified QuEChERS extraction technique, coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to optimize the identification of the cyflufenamid, a new broad-spectrum fungicide with unclear mode of action in toxicity, in 12 foodstuffs. The method has been validated according to the European Union SANTE/12682/2017 guidelines for its linearity, limit of detection (LOD), and limit of quantification (LOQ), indicating an excellent performance. The recovery of cyfluenamid in all matrix were ranged between 70.8% and 117.8%, with relative standard deviation (RSD) <15% which is much lower compared to other methods. The method has been used for determine cyfluenamid in foodstuffs followed the ISO17025:2017 measurement technical note, which demonstrated it is suitable for routine quantitative analysis of cyflufenamid in most of the popular commercial agricultural products.

Comparison of new approach of GC-HRMS (Q-Orbitrap) to GC-MS/MS (triple-quadrupole) in analyzing the pesticide residues and contaminants in complex food matrices

Performances of multiresidue analysis of one hundred of pesticides and contaminants, using GC-Q-Orbitrap method in full scan mode were compared to those obtained with GC-triple-quadrupole method in multiple reaction monitoring mode. In terms of sensitivity, 86% of molecules exhibited lower limit of detection values using GC-Q-Orbitrap than using GC-triple-quadrupole. For the GC-Q-Orbitrap method, more than 85% of the pesticides and contaminants showed good recovery [70-120%] in wheat samples, with relative standard deviation values < 20%. GC-Q-Orbitrap method appeared the most sensitive for most pesticides studied in wheat with limit of quantification values ranged between 0.1 µg/kg and 4 µg/kg. Moreover, the matrix effect was acceptable in wheat extracts for 84 molecules but strong suppression of the chromatographic signal was observed for 16 molecules for the GC-Q-Orbitrap method. The injection of unpurified wheat extracts spiked at 10 µg/kg proved the potential of the GC-Q-Orbitrap method for use in performing high-throughput pesticide screening.

[Rapid screening and confirmation of 415 pesticide residues in red cabbages by liquid chromatography-quadrupole-time of flight-mass spectrometry]

An analytical method for the simultaneous rapid screening and accurate confirmation of 415 pesticide residues in red cabbages was established using liquid chromatography-quadrupole-time of flight-mass spectrometry (LC-QTOF/MS) with single acquisition. In the established method, the pesticides in red cabbage were extracted using acetonitrile-acetic acid (99∶1, v/v) and salted-out using anhydrous magnesium sulfate and sodium chloride. The resultant solution was then cleaned-up by automatic solid phase extraction using a Carbon/NH2 cartridge. The SPE cartridge was activated with 4 mL acetonitrile-toluene (3∶1, v/v) and the effluents were discarded. The resultant solution was transferred to the Carbon/NH2 cartridge, using 3×2 mL acetonitrile-toluene (3∶1, v/v) to wash the test sample concentrate bottle, and waited until the surface of the test sample concentrate liquid reached the top layer of anhydrous Na2SO4 before transferring the washing liquid to the cartridge. A 30-mL reservoir was attached to the upper part of the SPE cartridge and 25 mL acetonitrile-toluene (3∶1, v/v) was used to wash the SPE cartridge again. The eluent was evaporated in the glass tube in a water bath at 37 ℃ and shaking speed 150 r/min to reduce the volume to 0.5 mL. Nitrogen was used to dry the concentrates, and the residues were dissolved in 1.0 mL acetonitrile-water (3∶2, v/v), homogenized by ultrasonication, and passed through 0.22-μm filtering membrane before determination. The dissolved sample solution was loaded onto a ZORBAX SB-C18 column (100 mm×2.1 mm, 3.5 μm) and separated under gradient elution using 0.1% (v/v) formic acid aqueous solution containing 5 mmol/L ammonium acetate and acetonitrile as the binary mobile phase. The eluent from the column was further detected by QTOF/MS under electrospray positive ionization in the MS/MS scanning mode. A matrix-matched external calibration method was used for quantitation. By optimizing the different parameters under Auto MS/MS and All Ions MS/MS acquisition modes, the optimal conditions for All Ions MS/MS under each acquisition mode were obtained, which were then compared for selection of a better mode. The results demonstrated that the developed method can be used to accurately screen and quantify all 415 pesticides in red cabbage. The linear regression correlation coefficients (r2) for the 415 pesticides were all greater than 0.990 in the corresponding linear concentration range. In addition, the screening detection limits (SDL) of 411 pesticides were no more than 5 μg/kg, and the limits of quantification (LOQs) of 413 pesticides were no more than 10 μg/kg. At the spiked levels of LOQ, two-fold LOQ, and 10-fold LOQ, the recoveries were in the ranges of 65.7%-118.4%, 72.0%-118.8% and 70.2%-111.2%, with relative standard deviations (RSDs) in the ranges of 0.9%-19.7%, 0.2%-19.9% and 0.6%-19.9%, respectively. The method was applied to detect pesticide residues in the red cabbage samples provided by the 2019 European proficiency test project for unknown pesticide screening (EUPT-SM-11) and accurate quantitation (EUPT-FV-21). For EUPT-SM-11, all the spiked and incurred pesticides in red cabbage were qualified accurately, without false positives or false negatives. This is completely consistent with the final results published by the EU official. For EUPT-FV-21, there were 19 non-volatile pesticides that can be detected by LC-MS, which were then accurately quantitated with the corresponding pesticide standard. The results demonstrate that the proposed method is accurate and reliable. It is also rapid and time-saving, and can be used for high-throughput screening and quantitative determination of pesticide residues in cabbage. It can also be extended to other fruits and vegetable matrices.

Simultaneous determination of 79 pesticides in pigeonpea grains using GC-MS/MS and LC-MS/MS

Pigeonpea grains are important sources of vegetarian proteins. It is the paramount importance to check the pesticide residues due to their frequent use during production. The LC-MS/MS and GC-MS/MS analytical method was developed and validated for the simultaneous determination of 79 pesticide residues in pigeonpea. The LOD and LOQ of the analytical method were in the range of 0.53 to 3.97 and 1.60 to 10.05 µg kg^-1, respectively, with a correlation coefficient of more than 0.997. Average recoveries were in the range of 80 to 118.8%, with the RSD of less than 15%. Measurement uncertainty (U_x) for pesticides was in the range of 3.42 to 12.76 µg kg^-1 evaluated at 50 µg kg^-1. The method was applied to analyze the sample collected from the farmer's field. This method could be useful for routine analysis of selected pesticide residue for monitoring purposes.

A two-step gas chromatography-tandem mass spectrometry method for measurement of multiple environmental pollutants in human plasma

Individuals are exposed to a wide variety of chemicals over their lifetime, yet current understanding of mixture toxicology is still limited. We present a two-step analytical method using a gas chromatograph-triple quadrupole mass spectrometer that requires less than 1 mL of sample. The method is applied to 183 plasma samples from a study population of children with autism spectrum disorder, their parents, and unrelated neurotypical children. We selected 156 environmental chemical compounds and ruled out chemicals with detection rates less than 20% of our study cohort (n = 61), as well as ones not amenable to the selected extraction and analytical methods (n = 34). The targeted method then focused on remaining chemicals (n = 61) plus 8 additional polychlorinated biphenyls (PCBs). Persistent pollutants, such as p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) and PCB congeners 118 and 180, were detected at high frequencies and several previously unreported chemicals, including 2,4,6-trichlorophenol, isosafrole, and hexachlorobutadiene, were frequently detected in our study cohort. This work highlights the benefits of employing a multi-step analytical method in exposure studies and demonstrates the efficacy of such methods for reporting novel information on previously unstudied pollutant exposures.

Magnetic particles encoding a suspension probe for ultra-sensitive and quantitative determination of atrazine

As a highly toxic and widely used herbicide, atrazine poses a serious threat to food safety as well as overall environmental and human health. Due to complex matrix interference and the difficulty of signal enrichment, there is an urgent need for a convenient, fast, and ultrasensitive method that detects trace atrazine without concern for matrix effects. Here, we provide the first account of a sensitive and rapid suspension probe based on magnetic microspheres used to detect atrazine in herbs. The self-made magnetic beads featured -COOH groups and were used as the carrier to construct immunofluorescent probes. These probes then conjugated with the atrazine antigen through an activated ester method, ultimately binding to the antibody. Homogeneous detection was ensured using flow cytometry and the microflow optical channel along with allophycocyanin-conjugated goat-anti-mouse secondary antibody (APC-IgG-SecAb) as the fluorescent signal. The magnetic suspension probe allowed for high target enrichment and the inherent two-dimensional selective detection of flow cytometry effectively avoided any matrix interference. This method had good linearity across 1.69-23.19 ng mL^-1. The IC₅₀ and LOD values were 4.81 ng mL^-1 and 0.95 ng mL^-1, respectively; the sensitivity was increased three-fold relative to ELISA. After complete optimization, 2-N-morpholinoeth-anesulfonic acid was used as the coupling solution and maintained good mono-dispersity, stability, and reactivity for the labelled microspheres during the process. The entire experiment was simple, and effectively used reagents; moreover, both the labor required and detection time were greatly reduced. Critically, the strategy presented here greatly reduced interference from complex matrices, and saved preparation for matrix-matched solutions when different herbs were screened. Overall, this strategy was sensitive, rapid, eco-friendly, and labor-saving; collectively, these attributes make it well-suited for on-site screening of atrazine contamination and will allow for increased food safety.

Application of Hydrophobic Magnetic Nanoparticles as Cleanup Adsorbents for Pesticide Residue Analysis in Fruit, Vegetable, and Various Soil Samples

A cleanup procedure based on hydrophobic magnetic nanoparticles for QuEChERS extraction followed by GC-MS method for the simultaneous determination of 16 organochlorine pesticides was developed. The type and amount of cleanup adsorbents (C18/GCB/Fe₃O₄/Fe₃O₄@Triton), the volume and polarity of the extraction solvent were optimized. The method was validated according to SANTE/11813/2017 and ICH/2005/Q2/R1 guidelines. Spiked-sample recoveries of 84-108% with RSD below 8% were obtained for all the tested pesticides in strawberry. Quantification was carried out using matrix-matched calibration plots, which displayed good linearity (R² > 0.99), the limits of quantification being less than the maximum residue limits (MRL) for food. The elaborated procedure with satisfactory results was applied in to determine the pesticides in fruit, vegetable (strawberries, avocadoes, watermelons, radishes, and flesh kiwis) and soil (agricultural, urban and lab-made) samples. The most frequently founded pesticide residues were 4,4'-DDE, 4,4'-DDD, lindane, and 4,4'-DDT, which in all cases were found to be below MRL. The highest concentration of 4,4'-DDT was founded in agricultural and lab-made soils.

Method validation for the analysis of pesticide residue in aqueous environment

Rapid industrialization and urbanization have led to severe pollution into water resources which limits to reach safe drinking and irrigation water globally. One of the most important pollutants of environment that brought along with industrialization and technology are pesticides. In this study, it was aimed to investigate the pesticide residues in Dim Stream, due to intense touristic and agricultural activities in the region. Thus, four locations alongside the river were selected for sampling to evaluate the pesticide residue in the stream. The water samples were collected representing the rainy and dry seasons and extracted according to the Quechers method which is validated in terms of accuracy, specificity, limit of detection (LOD), and quantification (LOQ). Pesticide residues were analyzed by injecting LC-MSMS and GC-MS. The most recurrent pesticides were cypermethrin, endosulfan, deltamethrin, dicofol, metribuzin, parathion-methyl, permethrin, malathion, and tetradifon in the samples. Some of the levels of pesticides detected in water were significantly high compared with guideline values set by the Surface Water Quality Regulation of Turkey, EU, and World Health Organization, and this may be hazardous to aquatic life and human health. The obtained 18 recoveries of pesticides in the samples varied between 70 and 120%. LOD was ranged 19 from 0.23 to 9.67 μg/L. LOQ of 11 of the pesticides were higher than 1 μg/L.

Determination of 66 pesticide residues in livestock products using QuEChERS and GC-MS/MS

Determinations of 66 pesticide residues in different matrices including beef, pork, chicken, eggs, and milk were conducted using GC-MS/MS combined with the quick easy cheap effective rugged safe (QuEChERS) method for sample extraction. A high linearity was achieved in the concentration range from 2.5 to 1000 µg/L (R ² ≥ 0.99), and the limit of quantification for multi-class pesticides ranged from 0.74 to 23.1 µg/kg. The recovery ranged from 70.0 to 120%, while the reproducibility of the measurements was between 0.23 and 19.9%. Monitoring was conducted for livestock products purchased from local markets. Chlorpyrifos and fenitrothion in beef and chlorpyrifos in pork were detected below the maximum residue limits for the respective samples. No detectable residues were found in the other samples. Due to its high efficiency, reproducibility, and simple analytical operation, the proposed method can be applied to the regular monitoring of multi-residue pesticides in livestock products.

Optimization of a Simplified and Effective Analytical Method of Pesticide Residues in Mealworms (Tenebrio molitor Larvae) Combined with GC-MS/MS and LC-MS/MS

An effective analytical method was optimized for residues including chlorpyrifos-methyl, deltamethrin, fenoxanil, thiobencarb and fludioxonil in mealworms, the larval form of Tenebrio molitor. They are listed for pest control during wheat cultivation and can be found in wheat-bran feed for growing mealworms in South Korea. Analytes were extracted using acetonitrile and salt packet. Four clean-up methods ((1) MgSO₄ + 25 mg PSA + 25 mg C18; (2) MgSO₄ + 50 mg PSA + 50 mg C18; (3) EMR-lipid^TM tube; and (4) 10 mL n-hexane) were investigated and the method (1) was selected due to its robustness. Low-temperature precipitation of fat and proteins improved the recoveries. Recoveries from the Method (1) were satisfying with 70-120% with <20% relative SD at a spiking level of 0.01 mg/kg. With the simultaneous sample preparation, fenoxanil, thiobencarb and fludioxonil were analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) and chlorpyrifos-methyl and deltamethrin by gas chromatography tandem mass spectrometry (GC-MS/MS). Quantification limits for LC-MS/MS and GC-MS/MS were 0.5 and 2.5 μg/L, respectively. No pesticides of interest were detected in 30 real samples collected across the nation. However, the data can be provided for establishing maximum residue limits for the pesticides in mealworms in response to the positive list system.

Exposure to multiclass pesticides among female adult population in two Chinese cities revealed by hair analysis

The high use of pesticides worldwide and the constant exposure of humans to these toxic-by-design chemicals have drawn the attention on the possible consequences on human health. However, information on the exposure of the general population to pesticides remain very limited in most countries, especially in urban areas. In the present work, hair analysis was conducted to investigate the exposure of 204 urban women living in two Chinese cities (Baoding and Dalian) to 110 pesticides and 30 metabolites of the following families: organochlorines, organophosphates, carbamates, pyrethroids, neonicotinoids, phenylpyrazoles, acid herbicides, urea herbicides and azoles. Results showed that 71 pesticides and 23 metabolites were found in the hair samples, with concentrations ranging up to 1070 pg/mg in hair. In each hair sample, the number of detected chemicals ranged from 25 to 50, demonstrating the cumulative exposure to pesticides among Chinese women in the studied regions. The concentrations of 38 chemicals (e.g., p-nitrophenol, diethyldithiophosphate, λ-cyhalothrin, permethrin, carbendazim and tebuconazole) were significantly different between women in Baoding and Dalian, indicating the regional differences in exposure to pesticide. Using a multiple regression analysis, we found that concentrations of a few dominant pesticides were associated with age, body mass index (BMI), cooking frequency and regions. These results can provide baseline information on exposure of female adult Chinese population to multiple pesticides and support future studies focused on the health effects associated with pesticide exposure.

High-throughput simultaneous analysis of multiple pesticides in grain, fruit, and vegetables by GC-MS/MS

A multi-component quantitative GC-MS/MS method for monitoring and inspecting agricultural products was developed for the simultaneous determination of 365 pesticide residues in grain, beans, fruit and vegetables. Twenty-six pesticides that have been authorised in foreign countries but not in Korea were included in the newly adapted Korean positive list system. The method was validated by analysing spiked samples at three concentrations (0.01, 0.05, and 0.1 mg/kg) for brown rice, soy beans, mandarin orange, potato and green pepper matrice, which represented grain, beans, fruit, and vegetables. More than 95% of 365 compounds satisfied the validation criteria of 70-120% recovery and ≤20% relative standard deviation obtained through the proposed simultaneous multi-component analysis. Twenty-two types of pesticides were detected in 76 food samples, whose concentrations were below the maximum residue limits. Among the newly added pesticides, lambda-cyhalothrin, an analogue of cyhalothrin, was detected in peaches. The method can be applied to the analysis and inspection of pesticide residues in domestic and imported agricultural products for safety control.

Dissipation of sixteen pesticide residues from various applications of commercial formulations on strawberry and their risk assessment under greenhouse conditions

Twelve commercial pesticide formulations containing sixteen active ingredients were applied on greenhouse strawberries at recommended and double doses. The dynamics and dietary risk analysis were investigated. A modified QuEChERS method based on the use of multi-walled carbon nanotubes (MWCNTs) as adsorbent followed by LC-MS/MS and GC-MS/MS detection was utilized for sample analysis. The half-lives of studied pesticides were 4.6-12.6 days and 3.8-15.8 days from two application doses. Dietary levels from the residue concentrations of the individual pesticides at harvest was contrasted with the acceptable daily intake (ADI) and acute reference dose (ARfD). The dietary risk assessment adopt the risk quotient (RQ) for chronic risk and risk probability (RP) for long-term dietary intake risk, respectively. The dietary risk induced by the studied pesticide residues in strawberry was acceptable for consumers except the pesticide fumigants. The pesticide residues at different pre-harvest intervals (PHIs) under greenhouse conditions were compared with the established maximum residue limits (MRLs). To reduce the residue levels and potential safety risk, a longer PHI or reduced application rates should be conducted.

Multiresidue analysis and evaluation of the matrix effect on 20 pesticides in Brazilian maize (Zea mays L.) flour

Maize consists of a cereal widely used in the preparation of different food products. Brazil is one of the world's largest maize producers. Several types of pesticides have been applied in maize crop, which can lead to the contamination of the derived products. The present work aims at the validation of multiresidue method to analyze the matrix effect and level of pesticides in maize flour. Twenty residues were investigated in samples commercialized in the state of Ceará, Brazil. The method was satisfactorily validated, according to parameters recommended by European Union. About 55% of the pesticides had an intense negative matrix effect. Multiresidue analyzes showed the presence of traces of fenitrotion in 20% of maize flour samples. Detected levels were below maximum residue limits recommended for maize. The results indicate that maize products need continuous monitoring to ensure food security.

Pt-Ni(OH)2 nanosheets amplified two-way lateral flow immunoassays with smartphone readout for quantification of pesticides

Excessive use of herbicide and insecticide causes bioaccumulation in the environment and increases potential toxicity for people and animals. Portable systems for rapid assays of herbicide and insecticide residues have attracted prominent interests. Here, we developed a two-dimensional (2D) Pt-Ni(OH)₂ nanosheets (NSs) amplified two-way lateral flow immunoassay (LFI) with a smartphone-based readout for simultaneous detection of acetochlor and fenpropathrin. The 2D Pt-Ni(OH)₂ NSs were synthesized and used as the enhanced signal label in the immunoassay due to their high peroxidase-like activity and low migration speed. The two-way LFI was designed to eliminate potential cross-reaction between two targets. Portable detection system was developed based on a smartphone-based readout, which scans the LFI and provides the accurate testing result. The universal use of smartphones makes the developed platform suitable for cheap and on-site applications. Using the integrated platform, detection of acetochlor and fenpropathrin simultaneously was successfully achieved with the detection limits of 0.63 ng/mL and 0.24 ng/mL, respectively. To confirm the performance of the on-site application, we detected 10 non-spiked samples and 3 spiked samples. The obtained detection results were consistent with the data from gas chromatography analysis. The estimated recoveries ranged from 97.12% to 111.46%, indicating the practical reliability of our developed assay. The developed smartphone-based platform exhibits enhanced sensitivity, which provides a promising technique for on-site, multiplex, highly sensitive detection of pesticides.