Non-polar Pesticides Research Articles

Validation of a global method for the simultaneous analysis of polar and non-polar pesticides by online extraction and LC-MS/MS

BackgroundMulti-residue methods for pesticide analysis in food are available for many compounds, but polar pesticides are not generally included due to their specific properties, which include high polarity and low molecular weight. Single residue methods are therefore needed for sample preparation, while chromatographic separation often requires derivatization, ion paring, or dedicated methods suitable for polar compounds, mostly ion chromatography and hydrophilic interaction liquid chromatography (HILIC). These challenges affect the important pesticide glyphosate and the related compounds aminomethylphosphonic acid (AMPA) and glufosinate. There are only a few methods including these compounds in large-scale analysis, mostly complex methods based on multidimensional chromatography. ResultsA new method, for the global online extraction and analysis of pesticides in beer was developed and validated. The method exploited an online trapping device, with reversed-phase (RP) and anion exchange properties, that can trap small molecules from liquid samples. The ion exchange mechanism was used to retain the very polar pesticides glyphosate, AMPA, and glufosinate. The hydrophobic properties of the trapping column were also exploited to trap pesticides suitable for multi-residue investigations. The chromatographic separation was optimized by comparison of HILIC and RP C30, which could separate pesticides, including the polar ones, with modulation by the trapping column after proper selection of the mobile phase composition and basic modifier. The validation for beer provided recoveries in the range 71–112 %, with <15 % RSD, and LOD and LOQ values of 0.02–1 and 0.3–3 μg L−1, respectively. The result was competitive with previous methods on polar pesticide analysis in beer. SignificanceThe method was validated for 15 pesticides, over the log Kow range from −4.4 to 4.5, using a methodology with single and fast chromatographic separation under conditions compatible with multi-residue analysis by RP-LC-MS/MS. In the case of beer, for which the method was validated, the sample preparation was also performed online, after simple degassing, and sample dilution.

Fate of pesticide residues in beer and its by-products

Sustainable beer production requires a comprehensive assessment of potential hazards such as pesticides in both the finished product and waste streams, as these streams can be used to create high-value by-products. This study presents the tracking of 13 fungicides (azoxystrobin, boscalid, epoxiconazole, fenpropidin, fenpropimorph, fluquiconazole, flutriafol, fluxapyroxad, kresoxym-methyl, spiroxamine, propiconazole, prothioconazole-desthio, and tebuconazole), two insecticides (chlorpyrifos-methyl and deltamethrin), one herbicide (glyphosate), and one growth regulator (mepiquat) through the beer brewing process. Field-treated rye, wheat, and barley samples containing pesticide residues were used as adjunct during brewing. Samples of the beer as well as the by-products (spent grain, spent hops, trub and spent yeast) were collected and extracted with a modified QuEChERS method for pesticide residues analysis using GC-MS/MS and LC-MS/MS. Results show that an average of 58% of pesticide residues are retrieved in the by-products with the highest fraction (53%) recovered in the spent grain, 4% in trub, 1% in spent hops, no residues detected in spent yeast and 9% in the beer. This is consistent with these nonpolar pesticides tending to remain adsorbed to the spent grain during brewing. Glyphosate and mepiquat, the most polar pesticides included in this study, showed a different behavior, with the largest fraction (>80%) being retrieved in sweet wort and transferred to the beer. Processing factors were generated for each pesticide from the adjunct to the beer and to the four by-products.

Simultaneous analysis of highly polar and multi-residue-type pesticides by heart-cutting 2D-LC-MS

Liquid chromatography-mass spectrometry (LC-MS) is currently the gold-standard technique for the analysis of non-volatile small organic molecules. However, one-dimensional liquid chromatography (1D-LC) cannot efficiently deal with mixtures of analytes with different physicochemical properties and, thus, specific chromatographic behaviour. As an alternative, this work proposes a two-dimensional liquid chromatography/high-resolution mass spectrometry (2D-LC-HRMS) approach for the simultaneous analysis of compounds with different polarities. It is based on the combination of hydrophilic interaction liquid chromatography (HILIC) in the first dimension (1D) and reversed-phase chromatography (RPLC) in the second dimension (2D), employing the heart-cutting methodology. The coupling between 1D and 2D was performed by a multiple heart-cutting (MHC) interface equipped with an active solvent modulation (ASM) valve. The aim of the study was the development of a 2D-LC methodology able to (i) acquire the 1D and 2D content by MS in a single analytical run, avoiding the loss of information caused by the MHC algorithm for filling the sampling loops; (ii) overcome the breakthrough problem caused by solvent incompatibility, modifying the 2D gradient during the ASM phase for this purpose. To evaluate the 2D-LC approach, pesticide residue analysis was proposed, selecting 20 pesticides covering a wide range of polarities (log Kow from −3.2 to 4.3) and including some of the so-called single residue method pesticides because of the difficulty of including them in 1D-LC multi-residue methods with satisfactory chromatographic resolution. The proposed strategy was to transfer in a single cut the void volume from the HILIC separation (consisting of the nonpolar pesticides) to the 2D for analysis under RPLC conditions. The developed assembly was assessed in a vegetable matrix (tomato) employing a hybrid QuEChERS/QuPPe sample treatment based on acetonitrile and methanol extraction. The proposed setup may be extended for 2D-LC applications where it is essential to acquire the entire content of both dimensions in a single data file just by coupling a selection valve to the MHC interface.

Novel Liquid Chromatography–Tandem Mass Spectrometry Method for Analysis of 102 Pesticides and Five Mycotoxins Regulated by the State of Colorado in Dried Hemp

A novel liquid chromatography–tandem mass spectrometry (LC–MS/MS) method with a dual electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) source was developed for analyzing 102 pesticides and five mycotoxins that are regulated by the state of Colorado in hemp. The limit of quantitation (LOQ) of the 102 pesticides and five mycotoxins met Colorado state action limit requirements for these analytes in a hemp matrix. For this study, 88 out of 102 pesticides and all five mycotoxins were analyzed using LC–MS/MS with an ESI source, whereas the remaining 14 pesticides were determined using LC–MS/MS with an APCI source. A simple, fast, green, and cheap acetonitrile solvent extraction method was used to extract the pesticides and mycotoxins from the hemp matrix with good extraction efficiency in the range of 80–120%. A hemp matrix is challenging and causes matrix effects such as ion suppression or enhancement. We optimized the LC method and added 30 internal standards to reduce and compensate for these matrix effects to obtain method accuracy in the range of 70–120%. The ionization mechanism of nonpolar pesticides (normally analyzed by gas chromatography–tandem mass spectrometry [GC–MS/MS]) with an APCI ion source was elucidated.

Optimisation and validation of a modified QuEChERS method for the determination of 222 pesticides in edible oils using GC-MS/MS: a case study on corn oil

ABSTRACT Recently, various pesticides have been employed at different stages of cultivation to protect the oil crop from insect, disease, and weed. Those pesticides, especially lipophilic ones, bio-accumulate in the oilseeds and get co-extracted into edible oils during the refining process. Hence, this study aimed to optimise an extraction method for routine pesticide multi-residue analysis in edible vegetable oil samples using gas chromatography coupled to tandem mass spectrometry (GC – MS/MS). Two parameters were optimised using a factorial design of experiment (solvent type and solvent/sample ratio). In general, the number of pesticides that conformed to our criteria (mean recovery 70–120%) increased as the solvent/sample ratio increased. Each of the three tested solvents had an advantage over the other, ethyl acetate showed the highest capability for non-polar pesticides extraction, acetonitrile had the highest sensitivity, and the ethyl acetate/acetonitrile mixture showed the highest number of pesticides with acceptable criteria. The three solvents were tested using two different cleanup sorbents (EMR, and Z-Sep), the best solvent/cleanup combination was found to be ethyl acetate/acetonitrile mixture in addition to Z-Sep. The final method was validated in accordance with the European guidelines for Analytical Quality Control and Method Validation Procedures for Pesticide Residues Analysis in Food and Feed (SANTE/11312/2021). The precision and trueness of the method were determined from recovery experiments on six replicates of spiked blank corn oil samples at 0.01, 0.025, and 0.05 mg/kg. The number of pesticides that showed accepted criteria were 130, 166, and 182 out of 222 for each spiking level respectively.

Agro-ecological risk of pesticides application for protecting apple plantations in the conditions of Pre-Carpathian Province of the Carpathian mountains in Ukraine

It was found that the rate of detoxification of pesticides depends on their physicochemical properties and correlates with the polarity of the compounds. According to the magnitude of dipole moments, the studied pesticides are divided into three groups: nonpolar with µ from 0 to 2 Debye (D), low-polar with µ from 2 to 6 Debye and polar with µ more than 6 Debye. Non-polar pesticides are practically insoluble in water and their decay period in the ecosystem is longer than that of low-polar and polar pesticides. Peculiarities, speed and dynamics of pesticide detoxification in the apple orchard ecosystem have been studied. It was found that non-polar pesticides decompose at a rate of 0.07–0.12±0.05 parts per day, and low-polar pesticides — at a rate of 0.15–0.22±0.05 parts per day. On the tenth day after spraying, 0.05 to 1.24 mg/kg of the studied pesticides were detected in apple fruits and from 0.15 to 4.41 mg/kg in apple leaves. The classification of pesticides according to the degree of danger was carried out and it was found that the studied drugs have a degree of danger from 3 to 6. Pesticides with 3 degrees of danger are more dangerous to humans and biota and require more detailed regulation, regulation and control. The seasonal load of pesticides (H) for the intensive chemical system was 29.5 kg/ha, for the advanced system — 10.5 kg/ha and for the system of biological and chemical protection — 0.45 kg/ha. The weighted average hazard (Q) in the intensive chemical protection system was 5.0, for the advanced system — 4.9, and for the biological and chemical protection system — 6.8. It was found that the agroecotoxicological index for all protection systems was less than 1, all protection systems are not very dangerous and do not lead to ecosystem pollution. For the intensive system of chemical protection, this figure ranged from 0.24 to 0.49, for the advanced — from 0.014 to 0.025, and for the system of biological and chemical protection — from 6·10–5 to 8·10–5.

Adsorption of pesticides and personal care products on pristine and weathered microplastics in the marine environment. Comparison between bio-based and conventional plastics

The hydrophobicity of persistent organic pollutants (POPs) makes them adsorb on microplastics in the marine environment, affecting their distribution, persistence, or their transfer to the trophic chain. Fragrances and non-polar pesticides can be adsorbed by microplastics in the marine environment because of their physico-chemical characteristics.In this work, the adsorption of two pesticides (α-endosulfan and chlorpyrifos) and 6 musk fragrances (musk xylene, musk ketone, musk moskene, galaxolide, tonalide, and celestolide) on polyamide (PA6) (a petroleum based polymer) and on polyhydroxybutyrate (PHB) (biopolymer) in seawater was studied, considering also the effect of water temperature and plastic weathering.Results show higher adsorption of the selected pollutants for PHB than PA, being PA more affected by the water temperature and the plastic weathering. The highest percentage of adsorption was achieved in most cases at 24 h. In addition, this process was irreversible, as it showed the leaching assays. Besides, this work revealed that plastics mitigate the degradation of α-endosulfan in aquatic media (hydrolysis), showing that plastics can act as inhibitors of degradation of POPs, increasing its persistence in the environment.

Multi-residue Methodologies for the Analysis of Non-polar Pesticides in Water and Sediment Matrices by GC–MS/MS

A multi-residue method for the analysis of non-polar pesticides by GC–MS/MS in water and sediment matrices has been successfully developed, including 33 and 27 compounds, respectively. Water analysis method is based on a classic liquid–liquid extraction with recoveries ranging between 39 and 102%, with RSDs lower than 13%, LODs of 0.42–15.2 ng L−1 and LOQs of 0.72–50.8 ng L−1. Sediment analysis method is based on a pressurized liquid extraction with recoveries ranging between 37 and 133%, RSDs lower than 18%, LODs of 0.01–0.16 ng g−1 dry weigth (dw) and LOQs of 0.02–0.54 ng g−1 dw. Reported LODs were lower than the maximum acceptable detection limits set by the EU Watch Lists for selected pesticides. Applicability of both methodologies has been evaluated in real water and sediment samples collected in Catalonian river basins reporting oxadiazon for the first time in sediments from Catalonian river basins with a range of n.d. to 382 ng g−1 dw and a mean concentration of 44.0 ng g−1 dw. The importance of the simultaneous evaluation of both water and sediment has been emphasised since ten out of the 15 detected pesticides in the sediments can pose a high risk to aquatic organisms according to the Risk Quotient (RQ) method. Further detailed work needs to be done to better understand and assess the environmental impact of pesticide-contaminated sediments on aquatic organisms.

Magnetic Solid-Phase Extraction (MSPE) Using Magnetite-Based Core-Shell Nanoparticles with Silica Network (SiO2) Coupled with GC-MS/MS Analysis for Determination of Multiclass Pesticides in Water.

For the analysis of pesticide residues in water samples, various extraction techniques are available. However, liquid-liquid extraction (LLE) and solid-phase extraction (SPE) are most commonly used. LLE and SPE extraction techniques each have their own disadvantages. The aim of the study was to develop an environment-friendly multi-residue method for determination of multiclass pesticides in environmental water samples (ground water, agricultural field/irrigation run-off water, etc.). The magnetic solid-phase extraction (MSPE) technique using surface-fabricated magnetic nano-particles was used for extraction of water samples, followed by quantification by gas chromatography tandem mass spectrometry. The developed multi-residue method was validated in terms of linearity, LOD, LOQ, recovery, and repeatability. Recovery data were obtained at the spiking concentration level of 1, 5, and 10 µg/L, yielding recoveries in the range of 70-120%. Overall, non-polar pesticides from all the groups, i.e., synthetic pyrethroid, organophosphorus, organochlorine, herbicides, and fungicides, show acceptable recovery percentages. Good linearity (r2 value ≥ 0.99) was observed at the concentration range of 0.5-100 µg/L. RSD values were found ≤ 18.8. The study shows that the method is specific, rapid, and low cost, as well as having a good linearity and recovery; thus, this method is applied in routine purposes for the analysis of pesticide residue in real water samples. Due to better adsorption ability, permeability, and magnetic separability, the functionalized nano-particles were found effective in the enrichment of 22 multiclass pesticides including organo-phosphorus, organo-chlorine, synthetic pyrethroid, herbicides, and fungicides.

Clay/au nanoparticle composites as acetylcholinesterase carriers and modified-electrode materials: A comparative study

This work presents the first comparative study on syntheses, characterization, and applications of different clay/gold nanoparticle composites (clay/AuNPs) as acetylcholinesterase (AChE) carriers and modified-electrode materials to detect chlorpyrifos, an organophosphate pesticide. The selected based-clays were plate-like kaolinite (Kaol; 1:1 aluminum phyllosilicate), globular montmorillonite (Mt; 2:1 aluminum phyllosilicate), globular bentonite (Bent; 2:1 aluminum phyllosilicate), and fibrous sepiolite (Sep; 2:1 inverted ribbons of magnesium phyllosilicate). The clay/AuNPs were synthesized using in situ chemical reduction of the gold precursor with anchoring 3-aminopropyl triethoxysilane (APTES) on the clay surfaces. The studied materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen adsorption/desorption, Fourier transformed infrared (FTIR) spectroscopy, thermogravimetric analyzer (TGA), zeta-potential analysis, and electrochemical impedance spectroscopy (EIS). Surface area, surface charges, and hydrophilic/hydrophobic nature of based-clays and the clay/AuNPs played major roles on AChE loading, residual activity, and sensor storage stability. The Mt/AuNPs was determined, among the studied clays, as the best supports for AChE loading and residual activities due to its high specific surface area and weak electrostatic interaction with the immobilized enzyme. Since apparent catalytic efficiencies kcatapp/KMappof the immobilized AChE in the four clay/AuNPs were found statistically similar, Mt/AuNPs which contained the highest enzyme loading was the favorite modified-electrode material. For chlorpyrifos detection, Kaol/AuNPs-based sensors resulted in the lowest detection limit, presumably due to the strong hydrophobic surface that helps to concentrate the nonpolar pesticide to the vicinity of the immobilized enzyme. Unfortunately, the highest electrostatic repulsion between the Kaol/AuNPs and AChE, and the dehydrated Kaol surface resulted in the lowest storage stability of the AChE pesticide sensors. Overall, Mt/AuNPs showed the highest potential as the AChE carrier and the modified electrode material for chlorpyrifos determination.

Gas chromatography-mass spectrometry based sensitive analytical approach to detect and quantify non-polar pesticides accumulated in the fat tissues of domestic animals.

A fast and simple technique is proposed for the detection and quantitative determination of six non-polar pesticides including pyrethroids (cypermethrin, deltamethrin), organochlorines (hexachlorobenzene, α-hexachlorocyclohexane) and organophosphorus (chlorpyrifos, fenitrothion) accumulated in fat tissues of local cattle, sheep and goats. Gas chromatography coupled to mass spectrometry detection (GC–MS) adapted to cleanup procedures based on solid-phase extraction from QuEChERS method was adopted. The work was performed for quantitative affirmation of most customarily used pesticides in Sulaymaniyah, Kurdistan Region of Iraq and also the impact of boiling (100 °C, 30 min) and broiling (176 °C, 20 min) on chosen pesticides was evaluated. Among the results of 150 fat samples presented, the dominant compound in cattle samples was hexachlorobenzene (0.236 mg kg−1); while, in sheep and goats it was deltamethrin (0.248 and 0.122 mg kg−1 respectively). Boiling reduced pesticide concentration significantly (P < 0.05) and the most reduced group was pyrethroids in both techniques. Good responses for the six analytes were obtained at validation level of 0.01–0.1 mg kg−1. The linear coefficient was between 0.9997 and 0.9999 and limits of detection (LOD) and quantification (LOQ) ranged 0.0052–0.014 mg kg−1 and 0.015–0.044 mg kg−1 respectively. Acceptable recoveries (81.5–98.6%) and relative standard deviation (0.3–9.3%) were obtained in different spiked levels. The validation results confirmed that the proposed GC–MS technique can be utilized as a dependable screening apparatus for the quantitative screening of studied pesticides in fat tissues with accuracy and sensitivity, if deployed along with solid-phase extraction based QuEChERS method.

Method development for simultaneous determination of polar and nonpolar pesticides in surface water by low-temperature partitioning extraction (LTPE) followed by HPLC-ESI-MS/MS.

During this research, chemometric approaches were applied for optimization of the low-temperature partitioning extraction (LTPE) for the simultaneous analysis of the pesticides: acephate, difenoconazole, fenamidone, fluazifop, fluazinam, methamidophos, and thiamethoxam from surface water samples and determination by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry. It was used the 23 full factorial and the Doehlert experimental designs. The extraction technique was optimized by evaluating the effects of the three variables: sample pH, ionic strength (addition of Na2HPO4), and organic solvent volume. Considering the interest to find an optimal condition for all analytes simultaneously, the best extraction parameters found were as follows: pH = 5.33, concentration of Na2HPO4 = 0.0088 mol L-1 and organic phase volume = 4.5 mL. The optimized methodology showed LOD and LOQ levels from 0.33 to 8.13 ng L-1 and from 1.09 to 26.84 ng L-1, respectively. The recovery values ranged from 38.37 and 99.83% and the RSD values varied from 2.33 to 18.92%. The method was applied to surface water analysis sampled in areas with intensive agricultural practices in Ouro Branco City, Minas Gerais, Brazil. The difenoconazole was detected in concentrations between 12.53 and 94.76 ng L-1.

Influences of sample homogenization time and standing time before extraction on the determination of incurred pesticide residue levels in grapes.

To estimate the influence of sample processing with a blender, we conducted a homogeneity test using a bulk sample of pre-harvest grapes. Relative standard deviations (RSDs) were calculated from the concentrations of pesticides in the portions from the top, middle, and bottom of the homogenate with fine and rough particles. The results from adequate sample processing showed that the RSDs of the residue levels of all five pesticides in the fine-particle homogenate were lower than 10%. In contrast, the results under problematic conditions such as short blending times and long standing times after blending showed higher RSDs (>15%). The RSDs of nonpolar pesticides showed greater variabilities under the problematic conditions than those of polar pesticides. Separate analyses of the precipitate and supernatant phases suggested that the distribution bias of skin particles in the homogenate has a major effect on the concentration of nonpolar pesticides because of weighing errors in the extracted portions.

Formulation of oil-in-water emulsions for pesticide applications: impact of surfactant type and concentration on physical stability.

Oil-in-water (O/W) emulsions can be utilized as effective pesticide delivery systems in the agricultural industry. In this study, the effects of hydrophile-lipophile balance (HLB), concentration, and location of surfactants on the formation and physical stability of O/W emulsions suitable for pesticide applications was investigated using dynamic light scattering and vertical laser profiling. A non-polar pesticide (lambda-cyhalothrin) was used as a model. The pesticide emulsion with the highest stability was obtained using a commercial non-ionic surfactant (polyoxyethylene castor oil ether, EL-20) with a required HLB value of 10.5. Emulsion stability increased as the surfactant concentration was increased from 2 to 6%, which was attributed to the formation of smaller oil droplets during emulsification. Emulsions prepared with the surfactant initially in the oil phase were more stable than those prepared with it initially in the aqueous phase. The optimum formulation of the pesticide emulsion was determined as follows: 5% lambda-cyhalothrin (active ingredient) and 6% EL-20 (surfactant) dissolved in 5% S-200 (aromatic hydrocarbon, as oil phase), then deionized water up to 100%, which met the quality indicators set by the FAO standards. The present study is expected to provide useful information to improve the stability of pesticide emulsions for commercial applications.

Pesticides in the atmosphere: a comparison of gas-particle partitioning and particle size distribution of legacy and current-use pesticides

Abstract. This study presents a comparison of seasonal variation, gas-particle partitioning, and particle-phase size distribution of organochlorine pesticides (OCPs) and current-use pesticides (CUPs) in air. Two years (2012/2013) of weekly air samples were collected at a background site in the Czech Republic using a high-volume air sampler. To study the particle-phase size distribution, air samples were also collected at an urban and rural site in the area of Brno, Czech Republic, using a cascade impactor separating atmospheric particulates according to six size fractions. Major differences were found in the atmospheric distribution of OCPs and CUPs. The atmospheric concentrations of CUPs were driven by agricultural activities while secondary sources such as volatilization from surfaces governed the atmospheric concentrations of OCPs. Moreover, clear differences were observed in gas-particle partitioning; CUP partitioning was influenced by adsorption onto mineral surfaces while OCPs were mainly partitioning to aerosols through absorption. A predictive method for estimating the gas-particle partitioning has been derived and is proposed for polar and non-polar pesticides. Finally, while OCPs and the majority of CUPs were largely found on fine particles, four CUPs (carbendazim, isoproturon, prochloraz, and terbuthylazine) had higher concentrations on coarse particles ( &gt; 3.0 µm), which may be related to the pesticide application technique. This finding is particularly important and should be further investigated given that large particles result in lower risks from inhalation (regardless the toxicity of the pesticide) and lower potential for long-range atmospheric transport.

Application of a biosorbent to soil: a potential method for controlling water pollution by pesticides.

Different strategies are now being optimized to prevent water from agricultural areas being contaminated by pesticides. The aim of this work was to optimize the adsorption of non-polar (tebuconazole, triadimenol) and polar (cymoxanil, pirimicarb) pesticides by soils after applying the biosorbent spent mushroom substrate (SMS) at different rates. The adsorption isotherms of pesticides by three soils and SMS-amended soils were obtained and the adsorption constants were calculated. The distribution coefficients (K d) increased 1.40-23.1 times (tebuconazole), 1.08-23.7 times (triadimenol), 1.31-42.1 times (cymoxanil), and 0.55-23.8 times (pirimicarb) for soils amended with biosorbent at rates between 2 and 75%. Increasing the SMS rates led to a constant increase in adsorption efficiency for non-polar pesticides but not for polar pesticides, due to the increase in the organic carbon (OC) content of soils as indicated by K OC values. The OC content of SMS-amended soils accounted for more than 90% of the adsorption variability of non-polar pesticides, but it accounted for only 56.3% for polar pesticides. The estimated adsorption of SMS-amended soils determined from the individual adsorption of soils and SMS was more consistent with real experimental values for non-polar pesticides than for polar pesticides. The results revealed the use of SMS as a tool to optimize pesticide adsorption by soils in dealing with specific contamination problems involving these compounds.

Alternative QuEChERS-based modular approach for pesticide residue analysis in food of animal origin.

The approach for pesticide residue analysis in food of animal origin differs strongly from the one established for food of plant origin, as laboratories mainly focus on conventional methods for the analysis of non-polar pesticides known to accumulate in fatty tissues. However, these group-specific methods are very laborious and cost intensive and typically require extraction of fat components followed by extensive clean-up steps to remove matrix constituents. This work highlights the development and validation of a straightforward QuEChERS-derived clean-up procedure enabling facile, precise, and reliable identification and quantitation of pesticide residues in food of animal origin, which can be extended to various other commodities with moderate fat content and applied to replace traditional group-specific methods. Two additional methods for lean and highly fatty commodities complete this well-established "simplified modular system". The proposed method was in-house validated in terms of accuracy and precision, recovery and linearity as well as specificity and sensitivity on two representative commodities for food of animal origin (egg and meat). For the majority of the more than 80 pesticides investigated, satisfactory results were obtained. Procedural matrix calibration was applied for screening purposes in conjunction with GC-MS/MS or LC-MS/MS as integral part of the approach. Apparent recoveries for most of the compounds ranged from 70 to 120 % (RSD < 20%) at spiking levels of 0.01 (LOQ level) and 0.05 mg/kg. Accuracy of the method has been demonstrated by application to reference material from previous EU proficiency tests. Only in case of positive screening results a standard addition approach was applied for precise quantitation.

High-Throughput Analytical Techniques for Determination of Residues of 653 Multiclass Pesticides and Chemical Pollutants in Tea--Part V: A Comparative Study of the Influence of Tea Hydration on the Efficiency of Pesticide Multiresidue Determination Using Three Sample Preparation Methods and GC/MS/MS.

This paper describes a comparative study of the influence of three sample preparation techniques (M1: hydration+oscillating extraction+partial extraction solution hexane partitioning cleanup; M2: hydration+oscillating extraction+overall extraction solution SPE cleanup; and M3: pure acetonitrile homogeneous extraction+overall extraction SPE cleanup) on the determination efficiency of 456 pesticide multiresidues in tea. First, it was discovered from the mathematical correlation equation of 329 pesticide recoveries established and log Kow values that the extraction efficiency of hydration method M1 has obvious correlation with pesticide log Kow, making the extraction efficiency of M1 take the shape of an arc trend line with a certain arc hanging down from both ends of polar pesticides and nonpolar pesticides. Second, regarding the M1 method, the interfering matter after co-extraction increased in large quantities, which markedly lowered the S/N of the target pesticides and method sensitivity, leading to an obvious decrease of the method efficiency. The fortification experiment of the uniform limit 0.010 mg/kg proved that with the M1 hydration method there are 23 pesticides with recoveries between 70 and 120% and RSD<20%, accounting for only 5.0%, while with nonhydration method M3 there are 229 pesticides, making up 50%.

Thin-layer chromatography/direct analysis in real time time-of-flight mass spectrometry and isotope dilution to analyze organophosphorus insecticides in fatty foods

To assess food safety emergencies caused by highly hazardous chemical-tainted foods, simultaneous analysis of organophosphorus insecticides in fatty foods such as precooked foods was conducted using thin-layer chromatography/direct analysis in real time time-of-flight mass spectrometry (TLC/DART-TOFMS) and isotope dilution technique. Polar (methamidophos and acephate) and nonpolar organophosphorus insecticides (fenitrothion, diazinon, and EPN) were studied. Experiments to ascertain chromatographic patterns using TLC/DART-TOFMS reveal that it was more useful than GC/MS or GC/MS/MS for the simultaneous analyses of polar and nonpolar pesticides, while obviating the addition of a protective agent for tailing effects of polar pesticides. Lower helium gas temperature (260°C) for DART-TOFMS was suitable for the simultaneous analysis of target pesticides. Linearities were achieved respectively at a lower standard concentration range (0.05–5μg) for diazinon and EPN and at a higher standard concentration range (2.5–25μg) for methamidophos, acephate, and fenitrothion. Their respective coefficients of determination were ≥0.9989 and ≥0.9959. A few higher repeatabilities (RSDs) for diazinon and EPN were found (>20%), although isotope dilution technique was used. Application to the HPTLC plate without an automatic TLC sampler might be inferred as a cause of their higher RSDs. Detection limits were estimated in the higher picogram range for diazinon and EPN, and in the lower nanogram range for methamidophos, acephate, and fenitrothion. Aside from methamidophos, recovery results (n=3) obtained using a highly insecticide-tainted fatty food (dumpling) and raw food (grapefruit) samples (10mg/kg) using TLC/DART-TOFMS with both complex and simpler cleanups were not as susceptible to matrix effects (95–121%; RSD, 1.3–14%) as those using GC/MS/MS (102–117%; RSD, 0.4–8.5%), although dumpling samples using GC/MS were remarkably susceptible to matrix effects. The coupled method of TLC with simpler cleanup and DART-TOFMS can be regarded as the same analytical tool as GC/MS/MS, which is useful to assess food safety emergencies caused by highly hazardous chemical-tainted foods.

Picogram per liter detections of pyrethroids and organophosphates in surface waters using passive sampling

Pyrethroids and organophosphates are among the most toxic insecticides for aquatic organisms, leading to annual-average environmental quality standards (AA-EQS) in the picogram per liter range in surface waters. For monitoring purposes, it is therefore crucial to develop very sensitive analytical methods. Until now, it is very difficult to reach detection limits at or below given AA-EQSs. Here, we present a passive sampling method using silicone rubber (SR) sheets for the sampling of ten pyrethroids and two organophosphates in surface waters. An analytical method was developed, optimized and validated for the extraction of the insecticides from the SR sheets by accelerated solvent extraction followed by clean-up on C18 and silica gel and detection with GC–MS/MS in positive ionization mode. Good precision (<20%) and absolute recovery (>50%) was observed for all substances, accuracy was between 66% and 139%. Limits of detection between 6 and 200 pg/L were achieved for all substances in surface waters using average sampling rates for PCBs and PAHs. The lack of substance-specific sampling rates and missing performance reference compounds led to an uncertainty in the concentration estimation of factor three in both directions. In a large field study, comprising 40 environmental samples from nine Swiss rivers, eight out of 12 substances were detected (most frequently: chlorpyrifos, cypermethrin). Most of the estimated organophosphate concentrations were between 0.1 and 1 ng/L, most pyrethroid detections below 0.1 ng/L. Four substances (chlorpyrifos-methyl, cypermethrin, deltamethrin and lambda-cyhalothrin) showed exceedances of their respective AA-EQS in multiple samples, also when the uncertainties in the concentration estimation were considered. As pyrethroid and organophosphate detection by SR passive sampling is very practicable and allows sensitive analysis, it has the potential to become a new tool in the monitoring of non-polar pesticides.