Pesticide Residues In Cereals Research Articles

Preparation and extraction property study of corn cob-like magnetic mosaic carbon materials derived from MOF-on-MOF composites

BackgroundLarge accumulations of pesticide residues in the environment eventually enter the human body with food. Based on magnetic solid-phase extraction (MSPE) technology, it is possible to achieve efficient extraction of trace pesticide residues in foodstuffs, and the construction of MSPE adsorbents with excellent magnetic properties and many active sites is still one of the main research topics. Based on this, we developed a new strategy for the preparation of "MOF-on-MOF" composites, which were carbonized and used as adsorbents for the extraction of pesticide residues in cereals. ResultsA novel corn cob core-shell composite Fe2O3@C@ZIF-8 was created by embedding ZIF-8 onto the surface of Fe2O3@C derived from MIL-88A(Fe), and used for the extraction of benzoylurea insecticides(BUs) from cereals. The adsorption behaviour between Fe2O3@C@ZIF-8 and BUs was investigated by static and kinetic experiments and the adsorption mechanism was elaborated. For the trace analysis of BUs, a magnetic solid-phase extraction combined with high performance liquid chromatography-ultraviolet detector (HPLC-UV) approach was also developed. Under the optimized experimental conditions, the limits of detection and quantification were 0.015–0.03 μg L−1 and 0.05–0.1 μg L−1, and the relative standard deviations for the intra-day and inter-day ranges were 1.82%–2.13 % and 3.85%–4.59 %, respectively. The spiked recoveries of the four cereals ranged from 82.72% to 104.45 %. After 10 cycles of use of Fe2O3@C@ZIF-8, the recoveries of BUs ranged from 77.90% to 96.74 %. SignificanceThe analytical method based on Fe2O3@C@ZIF-8 as adsorbent has a low limit of detection, a wide linear range and is highly applicable to the analysis of real samples. In addition, the strategy developed in this study for the preparation of thermoplastic polymer-assisted "MOF-on-MOF" composites has promising applications.

European Union Proficiency Tests for pesticide residues in cereals and feedstuff, from 2007 to 2022- Data collection experience

The European Union Reference Laboratory for pesticide residues in cereals and feeding stuff (EURL-CF) has, for 16 consecutive years since 2007, organized European Union Proficiency Tests (EUPTs) for analysis of multiple pesticide residues in various cereals and feedstuff commodities. The EUPTs are directed to National Reference Laboratories (NRLs), and official laboratories (OfLs) in European member (EU) states and in European Free Trade Association (EFTA) countries. The aim of the EUPTs is to gain information regarding the quality, accuracy and comparability of pesticide residue data in cereals and feedstuff reported by different EU and EFTA laboratories, to help evaluate and improve their performance. This article summarizes 16 years’ experience in processing and analyzing results for EUPTs for pesticide residues in cereals and feedstuff. It provides an overview of the performance and development of as many as 160 laboratories throughout the years. Results are highlighted in terms of the number of participants, analytical scope, z scores, false positive and false negative reported results, and classification of laboratories. The performance of laboratories in the EUPTs has improved over time. A notable increase was observed in NRLs and OfLs classified as category A, indicating satisfactory overall performance and scope coverage for the majority of participating laboratories.

Monitoring of Pesticide Multi Residues in Selected Cereals Crop Grains in United Arab Emirates

Assessing the contamination of cereals and their manufactured products with pesticide residues is a topic of global importance, and monitoring studies are needed to analyze multiple residues at trace levels. Current study was conducted to monitor pesticide residues in various cereals (corn, oats, rice, barley, sorghum and wheat) imported into the UAE as part of official surveillance. A total of 1,440 samples were collected during 2020 and 2021.
 Modified QuEChERS method for pesticide residue screening based on multi-reaction monitoring (MRM) mode with advanced gas and/or liquid chromatography tandem mass spectrometry were optimized for monitoring 400 pesticides residues in cereals, and the method was validated for oats, rice, barley and corn matrices, following the European Commission guidelines achieving good recovery values in the range 70–120% with relative standard deviation values lower than 20% and providing limits of quantification of the method in the low mg/kg range, in accordance to the maximum residue limits set by European policies and CODEX.
 Results from monitoring showed that among the Cereals Grains samples, 903 samples (62.7%) were free from detectable residues, while 419 samples (29.09%) contained residues and 121 samples (8.4%) had residues exceeded the MRLs allowed by the EU legislation and/or COEDX. Tricyclazole, Thiamethoxam, Carbendazim and Buprofesin were the most frequently detected exceeded the MRLs in samples.

Assessment of pesticide residues contamination in cereals and pseudo-cereals marketed in the Canary Islands

In this work, the development of an analytical method for the evaluation of a wide variety of pesticide residues in cereals and pseudo-cereals widely consumed has been carried out. A QuEChERS method was used as extraction and clean-up procedure prior to separation and quantification of the target analytes by ultra-high performance liquid chromatography coupled to mass spectrometry using a single quadrupole-time-of-flight analyser. The methodology was validated for oat, rye, spelt, barley and quinoa matrices, following the European Commission guidelines (SANTE/11312/2021), achieving good absolute recovery values in the range 60–124% with relative standard deviation values lower than 20% and providing limits of quantification of the method in the low mg/kg range, in accordance with the maximum residue limits established by European policies. Finally, considering the importance of cereals in general population diet, the analysis of 60 samples was carried out in order to assure their safe consumption.

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.

Development of Rapid and High-Precision Colorimetric Device for Organophosphorus Pesticide Detection Based on Microfluidic Mixer Chip.

The excessive pesticide residues in cereals, fruit and vegetables is a big threat to human health, and it is necessary to develop a portable, low-cost and high-precision pesticide residue detection scheme to replace the large-scale laboratory testing equipment for rapid detection of pesticide residues. In this study, a colorimetric device for rapid detection of organophosphorus pesticide residues with high precision based on a microfluidic mixer chip was proposed. The microchannel structure with high mixing efficiency was determined by fluid dynamics simulation, while the corresponding microfluidic mixer chip was designed. The microfluidic mixer chip was prepared by a self-developed liquid crystal display (LCD) mask photo-curing machine. The influence of printing parameters on the accuracy of the prepared chip was investigated. The light source with the optimal wavelength of the device was determined by absorption spectrum measurement, and the relationship between the liquid reservoir depth and detection limit was studied by experiments. The correspondence between pesticide concentration and induced voltage was derived. The minimum detection concentration of the device could reach 0.045 mg·L−1 and the average detection time was reduced to 60 s. The results provide a theoretical and experimental basis for portable and high-precision detection of pesticide residues.

Development of QuEChERS extraction method for the determination of pesticide residues in cereals using DART-ToF-MS and GC-MS techniques. Correlation and quantification study

Cereal crops comprise more than 60 % of agricultural production worldwide. To ensure high production, the extensive use of pesticides is common practice. Analysis of pesticide residues in food and particularly cereals has become an essential requirement for consumers, producers, food inspectors and authorities. However, the determination of pesticides in cereal samples is not an easy task due to the complexity of the matrices and the trace levels of pesticides. In this study, a simple and high-throughput method was validated for the determination of multi-residue pesticide in 30 different types of cereals which are commonly consumed around the world. QuEChERS procedure has been developed, a mixture of primary-secondary amine and C18 proved better performance for the reduction of the interfering substances from the cereal grains than multiwalled carbon nanotubes. For a comprehensive investigation, the pesticide cereals contents were purified following the established cleanup method and detected by DART-ToF-MS and GC-MS. As “soft” and “hard” MS ionization methods, DART-ToF-MS and GC-MS are strong nominated for comprehensive studies of the unknown molecules. The results showed that 19 pesticides were successfully identified by both techniques in all samples, 16 by DART-ToF-MS and 13 using GC-MS. Regarding the correlation between the developed methods, 10 pesticides were detected as a commonality between the two techniques, this indicates that a single MS technique is not sufficient to detect all of the existing pesticides in cereals. The findings exposed that the two MS techniques are complementary, and both can be used for comprehensive identification of the pesticides presented in cereals. Quantitative analysis was performed using GC-MS under the selective ion monitoring mode by external and internal standard methods. Tributyl phosphate has been used as an internal standard. The measured limits of detection ranged between 4 and 9 μg kg−1 for all pesticides, while the limit of quantification values was <34.8 μg kg−1, which were below the regulatory maximum residue limits. The coefficient of determination was >0.9980 within the calibration linearity range of 15–6250 μg kg−1 for the detected pesticides. The recovery of all detected pesticides was in the range 75.28–122.02 % (n = 3) with associated RSDs <14 % indicating satisfactory accuracy.

Safety of agricultural products: multicomponent determination of pesticide residues in cereals

Introduction. Cereal grain is an important part of the human daily diet and belongs to a large number of food items produced and consumed throughout the world. Cereals are cultivated using a long list of chemical plant protection products (herbicides, insecticides, fungicides, growth regulators). In this connection, the analysis of pesticide residues, including optimization, development of monitoring methods, and programs, is of particular importance. Purpose of the work. To create a multicomponent method for determining residual amounts of pesticides of various chemical classes and their metabolites in cereals. Material and methods. The identification and quantitative determination of the active substances of pesticides of various classes (neonicotinoids, triazoles, imidazoles, pyrethroids, organophosphorus compounds, strobilurins, etc.) in the joint presence were performed by methods based on the use of liquid and gas-liquid chromatography with mass spectrometric detection. The QuEChERS technology was used as a sample preparation method, based on the extraction of pesticides with an organic solvent from a homogenized grain sample in the presence of salts containing citrate buffer and purification of the extracts from polar compounds by solid-state dispersion extraction. Results. The developed multicomponent method for determining the residual amounts of pesticides of various chemical classes and their metabolites (40 items in total) in cereals was used to control the levels of xenobiotics studied in wheat, barley and corn samples produced in various regions of the Russian Federation (Moscow, Leningrad, Orel, Omsk, Voronezh, Ryazan, Rostov, Volgograd regions, Krasnodar Area), as well as in rice grain (the country of origin is the Socialist Republic of Vietnam) purchased using a consumer buying process. The identified levels of individual active substances were significantly lower than the established values of the maximum allowable level. Conclusion. The developed method is aimed at methodological support of food safety control.

The QuEChERS analytical method combined with low density solvent based dispersive liquid–liquid microextraction for quantitative extraction of multiclass pesticide residues in cereals

In this study, a combination QuEChERS and low density solvent based DLLME was developed for extraction and preconcentration of five multiclass pesticide residues including atrazine, ametryn, terbutryn, carbaryl and chlorothalonil, from selected cereals: Teff, barley and maize samples. Liquid chromatography with variable wavelength detector (VWD) was used for quantitative determination of the pesticides. Various experimental parameters affecting the extraction and the preconcentration efficiencies were optimized. Calibration curves constructed using Teff samples were linear over wide ranges, 7.1-200 μg kg-1 with R2 ≥ 0.990. LODs of the method were ≤ 8.9 μg kg-1, below the MRLs of EU for maize and barley. The RSDs were in the range of 2.3–9.5%. The method has also been applied to different cereal samples and satisfactory average recoveries ranging 69.0–117% were obtained for the spiked cereal samples at two concentration levels. Therefore, the developed method can be successfully utilized as a simple alternative for the analysis of multiclass pesticide residues in cereals and other related samples. KEY WORDS: QuEChERS method, Low density solvent based DLLME, Multiclass pesticide residues, Cereal samples, HPLC-VWD, Quantitative extraction Bull. Chem. Soc. Ethiop. 2017, 31(1), 1-15.DOI: http://dx.doi.org/10.4314/bcse.v31i1.1

Pesticide residues in grain from Kazakhstan and potential health risks associated with exposure to detected pesticides

This paper presents the first study of pesticide residue results in grain from Kazakhstan. A total of 80 samples: barley, oat, rye, and wheat were collected and tested in the accredited laboratory. Among 180 pesticides, 10 active substances were detected. Banned pesticides, such as DDTs, γ-HCH, aldrin and diazinon were found in cereal grain. Chlorpyrifos methyl and pirimiphos methyl were the most frequently detected residues. No residues were found in 77.5% of the samples, 13.75% contained pesticide residues at or below MRLs, and 8.75% above MRLs. The greatest percentage of samples with residues (29%) was noted for wheat, and the lowest for rye (20%). Obtained data were used to estimate potential health risks associated with exposure to these pesticides. The highest estimated daily intakes (EDIs) were as follows: 789% of the ADI for aldrin (wheat) and 49.8% of the ADI for pirimiphos methyl (wheat and rye). The acute risk from aldrin and tebuconazole in wheat was 315.9% and 98.7% ARfD, respectively. The results show that despite the highest EDIs of pesticide residues in cereals, the current situation could not be considered a serious public health problem. Nevertheless, an investigation into continuous monitoring of pesticide residues in grain is recommended.

Extension of the QuEChERS Method for Pesticide Residues in Cereals to Flaxseeds, Peanuts, and Doughs†

A simple method was evaluated for the determination of pesticide residues in flaxseeds, doughs, and peanuts using gas chromatography-time-of-flight mass spectrometry (GC-TOF) for analysis. A modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method, which was previously optimized for cereal grain samples, was evaluated in these fatty matrices. This extraction method involves first mixing the sample with 1:1 water/acetonitrile for an hour to swell the matrix and permit the salt-out liquid-liquid partitioning step using anhydrous MgSO(4) and NaCl. After shaking and centrifugation, cleanup is done by dispersive solid-phase extraction (d-SPE) using 150 mg of anhydrous MgSO(4), 150 mg of PSA, and 50 mg of C-18 per milliliter of extract. This method gave efficient separation of pesticides from fat and removal of coextracted substances better than gel permeation chromatography or use of a freeze-out step, which involved excessive use of solvent and/or time. The optimized analytical conditions were evaluated in terms of recoveries, reproducibilities, limits of detection, and matrix effects for 34 representative pesticides using different types of flaxseeds, peanuts, and doughs. Use of matrix-matched standards provided acceptable results for most pesticides with overall average recoveries between 70 and 120% and consistent RSDs <20% for semipolar pesticides and <26% for lipophilic pesticides. The recoveries of these latter types of pesticides depended on the fat content in the matrices and partitioning factor between the lipids and acetonitrile. We believe that the consistency of the pesticide recoveries for different samples in multiple experiments and the physicochemical partitioning explanation for <70% recoveries of lipophilic pesticides justify compensation of results for the empirically determined recovery values. In any case, this method still meets 10 ng/g detection limit needs for lipophilic pesticides and may be used for qualitative screening applications, in which any identified pesticides can be quantified and confirmed by a more intensive method that achieves >70% recoveries for lipophilic pesticides.

Proficiency test on incurred and spiked pesticide residues in cereals

A proficiency test on incurred and spiked pesticide residues in wheat was organised in 2008. The test material was grown in 2007 and treated in the field with 14 pesticides formulations containing the active substances, alpha-cypermethrin, bifentrin, carbendazim, chlormequat, chlorpyrifos-methyl, difenconazole, epoxiconazole, glyphosate, iprodione, malathion, pirimicarb, prochloraz, spiroxamin and trifloxystrobin. After harvest, the test material was additionally spiked in the laboratory with three pesticides, that where the residues were too low, and axozystrobin. In total, 72 laboratories submitted results and z-scores were calculated for all laboratories and pesticides, except for glyphosate where only five laboratories submitted results and summed weighted z-scores were calculated for the laboratories with a sufficient scope. For several pesticides, the submitted results were strongly depending on the extraction procedure and consequently the assigned values were calculated based on part of the results. Acceptable z-scores were obtained by 56–97% of the participants.

Determination of Pesticide Residues in Cereals by Liquid Chromatography and UV Detection

A chromatographic method to determine pesticide residues in cereals by high-performance liquid chromatography (HPLC) and ultraviolet (UV) detection has been described. The study focused on the preliminary purification procedure because of the analytical problems associated with the presence in these food matrices of high-molecular-weight compounds, such as lipids, triglycerides, celluloses, and starch, which can interfere and reduce the chromatographic separation efficiency of the analytes. The method proposed is based on the extraction of pesticide residues from 5 g of sample extracted with the use of petroleum ether and on cleanup with a C18 cartridge. The pesticides were eluted with acetonitrile. The column packed with solid support was eluted with a suitable solvent, and only a portion of flow outlet side of the UV detector was collected. Using the information of standard UV trace, it was possible to establish an appropriate portion and to ensure the collection of all pesticides analyzed. The simple and rapid proposal method has shown good recovery (70–110%) for different spiked levels of samples (0.025–0.1 mg/Kg) and could be applied to other food matrices that containing high-molecular-weight compounds.

High Throughput Analysis of N‐Methyl Carbamate Pesticides in Cereals and Beans by Dual Countercurrent Chromatography and Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometry

We developed a new analytical method for analysis of N‐methyl carbamate pesticides in cereals and beans using dual counter‐current chromatography (dual CCC) and liquid chromatography‐electrospray ionization tandem mass spectrometry (ESI LC/MS/MS). After pesticides were extracted from cereals and beans with ethyl acetate, each extract was cleaned up by dual CCC using a non‐aqueous binary solvent system composed of n‐hexane‐acetonitrile and analyzed by ESI LC/MS/MS with a short column. The average recoveries from cereals and beans fortified at the level of 0.01 ppm ranged from 73.9 to 119.6%, with the coefficients of variation from 0.7 to 6.8%. At the fortified level of 0.5 ppm, the recoveries ranged from 72.1 to 117.1% with coefficients of variation from 0.4 to 9.3%. The present analytical method of N‐methyl carbamate pesticides in cereals and beans is considered to be useful for monitoring the pesticide residues in cereals and beans.

Determination of Nine Organophosphorus Pesticides in Cereals and Kidney Beans by Capillary Gas Chromatography with Flame Photometric Detection

A method is developed for the determination of nine organophosphorus pesticide residues in cereals and kidney beans by capillary gas chromatography with flame-photometric detection. In this method, dichloromethane is used for clean-up after liquid-liquid extraction. It is shown that good separations are obtained using a fused-silica capillary column (DB-1701) by the optimized temperature program. In the spiked levels of 0.012-0.43 mg/kg, the recoveries are from 83.7% to 107%, with the relative standard deviation between 3.2% and 13% and limits of detection from 8.2 to 15 microg/kg. The method is rapid, sensitive, and practical.

Electronic pressure control of gas chromatography-mass spectrometry for the confirmation of pesticide residues in cereals and related products

An analytical method for the confirmation of 30 pesticide residues in cereals and related products has been developed. Splitless injection with electronic pressure control using constant carrier gas flow gives higher sensitivity and better resolution than electronic pressure control and isobaric analysis. The use of electronic pressure control assures consistent retention times enabling selected ions to be collected in short time windows. Mass spectrometric detection in the selected ion monitoring mode using three ions for each pesticide ensured good sensitivity and accurate pesticide confirmation.

Organochlorine pesticide residues in cereals in Nigerian markets

Organochlorine pesticide residues in cereals in Nigerian markets