Evaluation of common organic solvents for gas chromatographic analysis and stability of multiclass pesticide residues

Organophosphate Detection in Animal-Derived Foods Using a Modified Quick, Easy, Cheap, Effective, Rugged, and Safe Method with Liquid Chromatography-Mass Spectrometry

Organophosphates are widely used in the livestock industry. In this study, we developed a method for detecting 27 organophosphate insecticides in animal-derived foods, including beef, pork, chicken, milk, and eggs, using liquid chromatography-tandem mass spectrometry. A modified QuEChERS method was optimized for sample pretreatment. A mixture of acetonitrile and acetone was used as the extraction solvent, and MgSO4 and NaCl were used as salts. Among the five different dispersive solid-phase extraction systems, MgSO4, primary secondary amines, and C18 were selected for purification because they had the highest recovery rates and least matrix effects. The matrix-dependent limit of quantitation was 0.0005-0.005 mg/kg, and the correlation coefficient of the matrix-matched calibration curve was >0.99, which was acceptable for quantifying residues below 0.01 mg/kg-the default maximum residue limit in a positive list system. The recovery efficiencies ranged from 71.9 to 110.5%, with standard deviations ranging from 0.2% to 12.5%, satisfying the SANTE guidelines. The established analytical method was used to monitor organophosphates in animal-derived foods obtained from a local market, and no pesticides were detected. With respect to industry standards, our proposed method is recommended for practical organophosphate detection in animal-derived foods.

Comparison of different fast gas chromatography - mass spectrometry techniques (Cold EI, MS/MS, and HRMS) for the analysis of pyrethroid insecticide residues in food

In the multiclass, multiresidue analysis of pesticides in food and environmental samples, pyrethroid insecticides are generally more difficult to analyze than other types of analytes. They do not ionize well by electrospray ionization, and although they are suitable for analysis by gas chromatography-mass spectrometry (GC-MS), selectivity using standard electron ionization (EI) in GC-MS is often insufficient because the molecular ion is rarely present. Many pyrethroids tend to have the same fragment ions in MS or high-resolution (HR)MS, and similar ion transitions in tandem MS/MS, leading to difficulties in distinguishing different pyrethroids from each other and chemical interferences in complex matrices. In this study, different forms of fast GC coupled with different types of MS detectors were compared for the analysis of up to 15 pyrethroids in barley extracts as a test case to assess which approach was the most advantageous. The three studied GC-MS techniques consisted of Cold EI using supersonic molecular beams in selected ion monitoring (SIM) mode with a single quadrupole instrument; triple quadrupole MS/MS; and HRMS using an orbital ion trap (orbitrap). A higher flow rate was used in Cold EI, and low pressure (LP) GC was employed in the MS/MS and orbitrap methods, to speed up the GC analyses (<10 min chromatograms in all cases). Each technique had some advantages over the others depending on specific pyrethroid analytes in the matrix. Nontargeted LPGC-orbitrap typically yielded the highest selectivity, but it rarely achieved the needed detectability to quantidentify the residues at 10 ng g-1. Cold EI-SIM and LPGC-MS/MS usually met the needed detection limits and generally achieved similar capabilities for the targeted pyrethroids.

Ultrasonic-induced grafted lanthanum sulfide decorated multi-walled carbon nanotube onto bacterial cellulose applied for adsorption of pesticides in environmental waters

A new biosorbent was fabricated by modification of bacterial cellulose biopolymer grafted with lanthanum sulfide decorated carboxylated multiwall carbon nanotube (La2S3@MWCNT@BC). The sorbent was employed in a green alternative dispersive-solid phase extraction of a variety of 14 pesticides in environmental water samples. The analyses were performed using GC-µECD. The properties and structure of La2S3@MWCNT@BC nanocomposite were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and adsorption-desorption isotherms. The composition of the sorbent was also investigated to evaluate the adsorptive properties of its constituents. The impact of various parameters influencing extraction efficacies such as sorbent dose, adsorption time, sample pH, ionic strength, and desorption conditions was investigated. The method was validated by specificity, matrix effect % (-0.4 to -7.4), enrichment factor (4-10), limits of quantification (0.007-0.31 μg L-1), matrix-matched calibration linearity (0.01-200 µg L-1), determination coefficients (r2=0.9921-0.9998), and precision. The optimized method was applied for the analysis of multiclass pesticides in seven environmental and drinking waters and the recoveries were obtained in the 81-108 % range with RSDs of 2.5-4.7 %. This paper is the first report on the synthesis and use of La2S3@MWCNT@BC nanocomposite to extract pesticides from different water samples. The greenness of the procedure was evaluated by the AGREE protocols.

Effects of organophosphates on precision-cut kidney slices

Organophosphate (OP) poisoning, both accidental and with suicidal intent, is a global medical challenge. While the primary toxicity of these pesticides is based on the inhibition of acetylcholinesterase (AChE), case reports describe patients developing OP-mediated renal insufficiency. We set out to investigate possible pathomechanisms utilizing rat precision-cut kidney slices (PCKS). Depending on the method of investigation, PCKS were observed for a maximum of 10 days. PCKS exposed to OP compounds (malaoxon, malathion, paraoxon, parathion) showed a dose-dependent loss of viability and a reduction of total protein content over the course of 10 days. A concentration of 500 µM OP showed the most differences between OP compounds. After two days of incubation parathion showed a significantly lower level of viability than malathion. The respective effects of paraoxon and malaoxon were not significantly different from the control. However, effects of OP were only observed in concentrations exceeding those that were needed to achieve significant AChE inhibition in rat kidney tissue. In addition, we observed histological changes, without inducing LDH leakage. Overall, results suggest that OP exert effects in kidney tissue, that exceed those expected from the sole inhibition of AChE and vary between compounds. Without signs of necrosis, findings call for studies that address other possible pathomechanisms, including inflammatory response, oxidative stress or activation of apoptosis to further understand the nephrotoxicity of OP compounds. Monitoring oxon concentration over time, we demonstrated reduced enzyme-inhibiting properties in the presence of PCKS, suggesting interactions between OP compound and kidney tissue.

Simultaneous Analysis of 272 Pesticides in Agricultural Products by the QuEChERS Method and Gas Chromatography with Tandem Mass Spectrometry

The aim of this study is to develop a rapid and accurate method for simultaneous analysis of multi-residue pesticides and conduct pesticide monitoring in agricultural products produced by the production and distribution stage in Korea. The representative agricultural products were selected as brown rice, soybean, potato, mandarin, and green pepper and developed using gas chromatography with tandem mass (GC-MS/MS) for the analysis of 272 pesticide residues. The experimental samples were extracted by the QuEChERS-EN method and then cleaned up by using d-SPE, including MgSO4 and primary secondary amine (PSA) sorbents. The established method was validated in accordance with Codex CAC-GL/40, and the limit of quantitation (LOQ) was determined to be 0.01 mg/kg. A total of 243 pesticides satisfied the guidelines in five samples at three levels with values of 60 to 120% (recovery) and ≤45% (coefficient of variation, CV). The remaining 29 pesticides did not satisfy the guidelines, and these pesticides are expected to be used as a screening method for the routine inspection of agricultural products. As a result of analyzing 223 agricultural products in South Korea by applying the simultaneous analysis method, none of the detected levels in the samples exceeded the standard values based on maximum residue limits (MRLs). The developed method in this study will be used to inspect residual pesticides in agricultural products, and it is anticipated to contribute to the distribution of safe agricultural products to consumers.

Fate characteristics and risk identification of thifluzamide in buckwheat across China: Analytical method development, occurrence, and health assessment

Elaborating on the fate tendency of thifluzamide (thiazole-amide fungicide) in buckwheat based on nationwide application is vital for grain security and human health based on nationwide application. A rapid and sensitive analytical method was developed to trace thifluzamide in buckwheat matrices using an ultrahigh-performance liquid chromatography-tandem triple quadrupole mass spectrometer (UHPLC-MS/MS), with a retention time of 2.90 min and limit of quantitation (LOQ) of 0.001 mg/kg. Thifluzamide could be stably stored for 84 d in buckwheat matrices under -20 °C under dark condition. The occurrence, dissipation and terminal magnitudes of thifluzamide were reflected by the primary deposition of 0.02-0.55 mg/kg, half-lives of 12-14 d, and highest residues of 0.41 mg/kg. The long-term risks (ADI%) of thifluzamide were 37.268 %-131.658 % in registered crops, and the risks for the rural population were significantly higher than those of the urban population. The unacceptable dietary risks of thifluzamide should be continuously emphasized for children aged 2-7 with an ADI% values of 100.750 %-131.658 %. A probabilistic model was further introduced to evaluate the risk discrepancy of thifluzamide in buckwheat, showing the risks in Tartary buckwheat (Fagopyrum tararicum Gaerth) were 1.5-75.4 times than that in sweet buckwheat (Fagopyrum esculentum Moench). Despite the low risks for dietary buckwheat, the high-potential health hazards of thifluzamide should be pay more attention given the increasing applications and cumulative effects.

Stability Study and Handling Recommendations for Multiresidue Pesticide Mixes under Diverse Storage Conditions for LC-MS/MS and GC-MS/MS

BACKGROUND

In response to the growing global need for pesticide residue testing, laboratories must develop versatile analytical methods and workflows to produce scientifically sound results. One of the many challenges faced by food chemists is acquiring suitable pesticide certified reference materials (CRMs) to calibrate analytical equipment, monitor method performance, and confirm the identity and concentration of hundreds of pesticide residues in food samples. CRM producers invest considerable resources to ensure the stability of their products.

OBJECTIVE

To present proper CRM handling and storage practices as guidance to ensure stability based on the results of several multiresidue pesticide stability studies.

METHODS

The open ampoule and combined multiresidue mix studies were conducted under controlled conditions. New ampoules containing multiresidue pesticide CRM mixtures were opened and compared to previously opened ampoules at multiple intervals while stored under freezing and refrigerated temperatures. Both LC- and GC-amenable pesticides (>200 residues) were combined and stored under typical laboratory conditions. Studies were performed with and without celery matrix.

RESULTS

The open ampoule study showed high levels of stability for all mixtures. All GC residues remained stable over the duration of the experiment. A week after opening LC multiresidue pesticide mixtures showed minor degradation. After combination of the multiresidue pesticide mixtures, degradation occurred rapidly for both the GC and LC mixtures.

CONCLUSION

Multiresidue pesticide mixtures are stable as ampullated until they are opened. Once the contents of a kit were opened and combined, decreasing stability was observed over time. This was true for both the LC and GC kits. Working mixtures of CRMs for instrument calibration should be made daily.

HIGHLIGHTS

This article shows a novel approach for measuring stability of CRM mixes. In-depth analysis of multiresidue pesticide mixtures and the stability that can be expected before and after mixing under typical storage conditions is described.

Residue behavior and efficacy of benzothiazole in grains under different fumigation conditions

BACKGROUND

Benzothiazole is a potential grain fumigant for Tribolium castaneum. However, its safety profile and suitable fumigation conditions remain unknown. We therefore investigated the insecticidal efficacy, accumulation and dissipation of benzothiazole in grains (wheat, corn and rice) under different temperatures.

RESULTS

We established a universal detection method (modified QuEChERS coupled with GC-MS/MS) of benzothiazole residues in three grains, which provided high linearity (R2  > 0.999), sensitivity (limits of detection = 0.001 mg/kg, limits of quantification = 0.002-0.005 mg/kg), accuracy (recoveries = 88.18-118.75%) and precision (relative standard deviations < 4.78%). The insecticidal efficacy order of benzothiazole was 30 ≥ 10 > 20 °C and corn > wheat > rice. Temperature positively affected the accumulation/dissipation rate of benzothiazole. Rice was the most easily accumulated and dissipated grain for benzothiazole residues, while corn accumulated benzothiazole more than wheat but less than rice, with dissipation slower than wheat and rice.

CONCLUSION

Our results provide important references for the application of benzothiazole and other fumigants. © 2023 Society of Chemical Industry.

Health risks of dietary ethirimol exposure demand attention in China: A study of nationwide applications

The health risks for dietary exposure after large-scale ethirimol application demand attention to protect the human population from hazardous effects. The occurrence, dissipation and terminal magnitude of ethirimol were revealed by original deposition of <0.005-28.1 mg kg-1, half-lives of 0.6-14.5 d, and terminal concentrations of  spinach > leaf lettuce > pepper > cucumber > papaya > pumpkin > stem lettuce > muskmelon > wax gourd > mango. The high-potential health risks of ethirimol should be continuously emphasized for susceptible children aged 2-13 years, especially those residing in rural areas and presenting increasing vegetable intake.

Fate and occurrence of indoxacarb during radish cultivation for multi-risk assessment

Agrochemical indoxacarb is an important tool for selective pest control in radish that be consumed globally. A rapid and sensitive analytical method UHPLC-MS/MS was developed for tracing indoxacarb in radish leaves and roots with LOQ of 0.001 mg/kg and RT within 2 min, which were confirmed the satisfied storage stability of indoxacarb in radish matrixes with degradation rates less than 30 %. The occurrence, pharmacokinetics dissipation and concentration variation of indoxacarb were reflected by the original deposition of 2.23-4.12 mg/kg, half-lives of 2.6-8.0 d and terminal magnitude of 0.17 × 10^-2-25.46 mg/kg in radish, and the influencing factors were further illustrated in terms of climate factors, crop cultivars and soil properties. The highest residues of indoxacarb were 25.46 mg/kg in leaves and 0.12 mg/kg in roots, which were higher than international maximum residue limits. A probabilistic model, as well as deterministic model, were introduced to evaluated the health risks of indoxacarb offering a better description for uncertainty. The total chronic dietary risk values of indoxacarb were 146.961-482.065 % in 12 registered crops, of which ADI % in radish was accounted for 19.8 % with risk dilution effects. The unacceptable acute dietary risks of 121.358-220.331 % were observed at 99.9th percentile, whereas the high-potential non-carcinogenic effects were observed over 90th percentile (105.035-1121.943 %). The health risks should be continuously emphasized given the increasing applications and persistent characteristics of indoxacarb, which is vital to protect the human population from hazardous effects, particularly for vulnerable children.

Evaluation of polycyclic aromatic hydrocarbons content of herbal medicine products in Korea by HPLC-FLD

The objective of this study was to quantify four polycyclic aromatic hydrocarbons (PAH4) in herbal medicine products in Korea. The PAH4 (benzo[a]anthracene, benzo[b]fluoranthene, chrysene, and benzo[a]pyrene) were analyzed in 70 popularly used herbal medicine products without containing essential oil and containing essential oil matrices, using 3-methylcholanthrene as the internal standard. Ultrasonication and liquid-liquid extraction were followed by HPLC-FLD analysis. Satisfactory linearity (R 2 = 0.99), limit of detection (0.05-0.18 μg/kg), limit of quantification (0.14-0.54 μg/kg), recovery (85.72-112.18%), and precision (0.22-2.90%) of PAH4 were acquired. PAH contamination was detected in all herbal medicine products without containing essential oil and containing essential oil matrices types. In 44 samples of herbal medicine products, all PAH4 were detected, and in two samples of the other herbal medicine products, only benzo[b]fluoranthene was detected. The average concentration of PAH4 was 3.88 μg/kg. The validated analytical method was used for preventing human health risks related to the consumption of herbal medicines.

Simultaneous Determination of Pyrethroid Insecticides in Foods of Animal Origins Using the Modified QuEChERS Method and Gas Chromatography-Mass Spectrometry

Pyrethroid insecticides are used in agriculture to treat parasites in livestock. This study developed a simultaneous residue analysis method to measure seventeen pyrethroid insecticides in foods of animal origin, including beef, pork, chicken, milk, and eggs. The method, which comprises instrumental analysis using gas chromatography-tandem mass spectrometry and a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method for pretreatment, was optimized to verify the applicability of the method. A mixture of acetonitrile, ethyl acetate, and original salt (MgSO4 4 g, NaCl 1 g) was used as the extraction solvent and salt. MgSO4 (150 mg) primary secondary amine (25 mg) and graphitized carbon black (25 mg) were selected for dispersive solid phase extraction (d-SPE). The method limit of quantitation was 0.01 mg/L, and the linearity of the matrix-matched calibration curves was reasonable (R2 > 0.99). Recovery tests were performed at three concentrations (LOQ, 10 LOQ, and 50 LOQ). Good recoveries (75.2109.8%) and reproducibility (coefficient of variation <10%) were obtained. The matrix effects were in the range of −35.8 to 56.0%. The established method was fully validated and can be used as an official analytical method for quantifying pyrethroid insecticides in animal commodities.

Dissipation behavior, residue transfer, and safety evaluation of chlorantraniliprole and indoxacarb during tea growing and brewing by ultrahigh-performance liquid chromatography-tandem mass spectrometry

A reliable and simple analytical method was developed and validated to simultaneously determine chlorantraniliprole and indoxacarb in tea using ultrahigh-performance liquid chromatography-tandem mass spectrometry. The average recoveries of chlorantraniliprole were in the range of 86-110%, with the precision of intraday (n = 5) and interday (n = 15) ranging from 1.9 to 8.4% and from 2.4 to 8.8%, respectively. The average recoveries of indoxacarb were in the range 81-105%, with the precision of intraday (n = 5) and interday (n = 15) ranging from 2.0 to 9.8% and from 2.7 to 9.1%, respectively. The limits of quantification (LOQs) were all 0.01 mg/kg. The results based on the supervised field trials showed that chlorantraniliprole and indoxacarb in two tea samples followed first-order kinetics models with half-lives of 2.2-4.7 days and 2.5-3.5 days, which could be regarded as a moderately degrading pesticide. The terminal residues of chlorantraniliprole and indoxacarb in made tea were below 6.7 and 4.5 mg/kg, respectively, lower than their corresponding maximum residue limits (MRLs) established by several major countries and organizations (50 and 5 mg/kg). The leaching rates of chlorantraniliprole and indoxacarb during the tea brewing ranged from 4.78 to 12.62% and 4.13 to 10.67%, respectively. The chronic intake risk quotient (RQc) values for chlorantraniliprole and indoxacarb were 0.24% and 35.10%, while the acute dietary risk assessment (RQa) value of indoxacarb was 5.8%, which were all much lower than 100%. The results in the present study indicated that the health risk posed by the chlorantraniliprole and indoxacarb mixture pesticides was negligible in tea for consumers at the recommended dosages.

QuEChERS-based analytical methods developed for LC-MS/MS multiresidue determination of pesticides in representative crop fatty matrices: Olives and sunflower seeds

Oilseed crops are greatly extended all over the world. Their high fat content can interfere during pesticide multiresidue analysis through liquid chromatography-tandem mass spectrometry (LC-MS/MS). This work aimed at overcoming this issue by developing and validating two QuEChERS-based methods for LC-MS/MS determination of 42 pesticides in two fatty food matrices: olives and sunflower seeds. Optimization of the extraction method was achieved following a 2^6-2 fractional factorial design in a highly cost-effective way. Validation of the multi-residue methods demonstrated improved limits of detection, below the established maximum residue levels (MRLs) for almost all compounds, good precision, and trueness, in compliance with SANTE guidelines. Application of these methods to the analysis of real samples from the Iberian Peninsula showed the presence of some pesticides of relevant environmental concern, including four compounds contained in the Pesticide Action Network International list of highly hazardous pesticides, found at levels between 0.03 ng/g and 104 ng/g.

Determination of 52 hidden chemical pesticides in biopesticide products by GC-MS/MS and LC-MS/MS

Addition of chemical pesticides in biopesticides are expected to be common, due to effect of pest control during plant protection. These hidden chemical pesticides may cause various food safety problems if consumed. The purpose of our study was to develop a method to determine 52 hidden chemical pesticides in three formulation biopesticide products. Optimizations of different parameters, such as the instrument analysis condition for target, the extraction, and the composition of clean-up materials were carried out. The developed method used acetonitrile as an extraction solvent for all biopesticide formulations. The composition of adsorbents was based on QuEChERS, called QuSEL which was a needle filter head, containing PSA, GCB, and MgSO₄. Fifty-two chemical pesticides residues were then analyzed by GC-MS/MS and LC-MS/MS. The present results showed good linearity by correlation coefficients of more than 0.99 for all analyses. The LOQ ranged from 5.0 to 20.0 μg kg^-1. Recoveries of 32 chemical pesticides ranged from 71.9% to 118.4% at the spiked level of 10, 50, and 100 μg kg^-1, and 20 chemical pesticides ranged from 75.3% to 119.8% at the spiked level of 5, 25, and 50 μg kg^-1. The developed method was applied for biopesticide products, and 9 samples were positive in 20 samples.

Simultaneous Determination of Multi-Class Pesticide Residues and PAHs in Plant Material and Soil Samples Using the Optimized QuEChERS Method and Tandem Mass Spectrometry Analysis

New analytical approaches to the simultaneous identification and quantification of 94 pesticides and 13 polycyclic aromatic hydrocarbons (PAHs) in five representative matrices (pepper, apple, lettuce, wheat, and soil) were developed. The analyses were based on gas chromatography coupled with triple quadrupole tandem mass spectrometry (GC-MS/MS). The procedure was optimized by changing the solvent used during the extraction, from acetonitrile to the acetone: n-hexane mixture at a volume ratio of 1:4 (v/v), as well as the use of a reduced amount of water during the extraction of compounds from cereals. An additional modification was the use of florisil instead of GCB in the sample cleanup step. A full method validation study was performed, at two concentration levels (LOQ and 1000 × LOQ), which showed satisfactory results for all analytes from the PAHs group, with recoveries ranging from 70.7-115.1%, and an average RSD of 3.9%. Linearity was tested in the range of 0.001-1.000 mg/kg and showed coefficients of determination (R2) ≥ 0.99 for all PAHs. Satisfactory recovery and precision parameters (LOQ and 100 × LOQ) were achieved for almost all analytes from the pesticide group in the range of 70.1-119.3% with the mean RSD equal to 5.9%. The observed linearity for all analytes in the concentration range of 0.005-1.44 mg/kg was R2 ≥ 0.99, with the exception of famoxadone, chizalofop-p-ethyl, prothioconazole, spirodiclofen, tefluthrin, and zoxamid. The extended uncertainties were estimated, using a top-down approach of 9.9% (average) and 15.3% (average) for PAHs and pesticides samples, respectively (the coverage factor k = 2, the 95% confidence level). Ultimately, the method was successfully applied to determine pesticide residues in commercial samples of fruit, vegetables and grain, and soil samples for PAHs, which were collected from selected places in the Podkarpacie region. A total of 38 real samples were tested, in which 10 pesticides and 13 PAHs were determined. Proposed changes allow us to shorten the sample preparation time (by 20%) and to reduce the consumption of organic solvents (by 17%). The use of florisil for sample cleanup, instead of GCB, improves the recovery of compounds with flat particles.

Microextraction technique associated with gas chromatography-mass spectrometry for determining pesticide residues in urine

Urine is one of the biological matrices most used for detecting human contamination, as it is representative and easily obtained via noninvasive sampling. This study proposes a fast, accurate, and ecological method based on liquid-liquid microextraction with low-temperature partition (μLLE/LTP). It was validated to determine nine pesticides (lindane, alachlor, aldrin, chlorpyrifos, dieldrin, endrin, DDT, bifenthrin, and permethrin) in human urine, in association with gas chromatography coupled with mass spectrometry (GC-MS). The technique was optimized through a factorial design. The best conditions for the simultaneous extraction of the analytes comprised the addition of 600 µL of water and 600 µL of acetonitrile (extracting solvent) to a 500-µL urine sample, followed by vortexing for 60 s. By freezing the samples for 4 h, it was possible to extract the pesticides and perform the extract clean-up simultaneously. The parameters selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, and accuracy were used to appraise the performance of the method. Good values of selectivity and linearity (R² > 0.990), LOQ (0.39-1.02 μg L^-1), accuracy (88-119% recovery), and precision (%CV ≤ 15%) were obtained. The μLLE/LTP-GC-MS method was applied to authentic urine samples collected from volunteers in Southeast Brazil.

Hydroxycamptothecin (HCPT)-loaded PEGlated lipid-polymer hybrid nanoparticles for effective delivery of HCPT: QbD-based development and evaluation

Lipid-polymer hybrid nanoparticles (LPNs) are promising drug delivery systems in various of disease treatment areas, particularly for cancer treatments. Here, a water-insoluble antitumor agent, hydroxycamptothecin (HCPT), was successfully incorporated into LPNs formed from polylactic-co-glycolic acid (PLGA), 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-(methoxy(polyethylene glycol)-2000) (DSPE-PEG2000), and lecithin, by a modified single emulsification-solvent evaporation method. Quality-by-design (QbD) strategy composed of Plackett-Burman and Box-Behnken designs were applied for optimizing HCPT-LPNs with desired properties. The optimized HCPT-loaded lipid-polymer hybrid nanoparticles (HCPT-LPNs) were on the nanoscale, with a final size of 220.9 nm, drug loading of 2.50%. HCPT-LPNs were highly stable in plasma and had pH- and drug loading-related sustained release characteristics. The in vitro cytotoxicity of HCPT-LPNs against MCF-7 and HepG2 cells showed that HCPT-LPNs had higher in vitro cytotoxicity than HCPT solution (HCPT-Sol) with reduced cell viability and IC50 values. In vivo pharmacokinetic assays demonstrated that the AUC of HCPT-LPNs was more than 3 times higher than that of HCPT-Sol after tail vein injection in SD rats. Tumor growth was significantly inhibited compared with HCPT-Sol after a single tail vein injection of HCPT-LPNs in murine LLC-GFP-luc lung cancer bearing mice at a dose of 6 mg/kg, without severe side effects. These results indicate that HCPT-LPNs are the promising drug delivery system for antitumor treatments.

A LC-MS/MS method with electrospray ionization and atmospheric pressure chemical ionization source for analysis of pesticides in hemp

BACKGROUND

Pesticide testing for hemp has traditionally focused on techniques like QuEChERS with dSPE and SPE which demand time-consuming sample preparation, typically resulting in poor recovery rates for some pesticides, and requires the use of both LC-MS/MS and GC-MS/MS based instruments to cover the analysis for all regulated pesticides. In this study, we describe a streamlined approach for working with LC-MS/MS featuring a dual electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) sources using solvent extraction for faster and easier sample preparation and with 80-120% recovery for the analysis of all of 66 pesticides (regulated by California state in cannabis) with low detection limits in hemp.

METHODS

A simple solvent extraction with acetonitrile was used to extract pesticides from hemp. A LC-MS/MS system with dual ESI and APCI source was used to determine sensitivity for the analysis of 66 pesticides in hemp matrix, 62 pesticides were analyzed using an 18-min LC-MS/MS method with an ESI source and the other 4 pesticides were measured using a 6-min LC-MS/MS method with an APCI source.

RESULTS

The limit of quantitation (LOQ) of all 66 pesticides in hemp was in the range of 0.0025-0.1 μg/g which was well below the California state action limits of these analytes in cannabis products. A simple, fast, and cost-effective solvent extraction method was used for sample preparation to get good recovery in the range of 80-120% with RSD less than 20%. The unique ionization mechanism of chlorinated pesticides such as pentachloronitrobenzene using the LC-MS/MS system with an APCI source was elucidated. The proficiency test report generated with the LC-MS/MS method showed acceptable results for all of 66 pesticides in hemp with all of th z scores less than 2 with no false positives and negatives. The stability data collected over 5 days showed RSD less than 20% for 66 pesticides in hemp, and this demonstrated the robustness of the LC-MS/MS system used in this work.

CONCLUSIONS

A LC-MS/MS method with dual ESI and APCI sources was developed for the analysis of 66 pesticides in hemp. The recovery of all pesticides from a hemp matrix was in the acceptable range of 80-120% with RSD less than 20%.

Multi-residue method validation and safety evaluation of pesticide residues in seed spices cumin (Cuminum cyminum) and coriander (Coriandrum sativum) by gas chromatography tandem mass spectrometry (GC-MS/MS)

The manuscript reports comprehensive multi-residue determination of 215 pesticides in two commercially important Indian spices, Cumin (Cuminum cyminum) and Coriander (Coriandrum sativum) by GC-MS/MS analysis. The proposed method involved liquid-liquid extraction with acetonitrile, d-SPE clean-up and final reconstitution of extract in ethyl acetate. d-SPE clean-up with PSA and C18 minimized the matrix effects by 40 and 16%, respectively. Reconstitution of final extract reduced the non-volatile matrix co-extractives by 36-40%. The method was validated as per SANTE/12682/2019 and recoveries at 10, 25 and 50 μg kg^-1 were within 70-120% with RSD ≤ 20%. A fit for purpose method LOQ of 10 μgkg^-1 was achieved for 85% of analytes. The method was successfully applied for comprehensive screening of cumin and coriander market samples. The calculated TMDI for acute and chronic exposure assessment were less than calculated MPI in respective matrices and therefore did not cause any adverse effect to consumers.

Effect of storage states on stability of three organophosphorus insecticide residues on cowpea samples

BACKGROUND

The stability of pesticide residues in stored samples is very important to ensure the quality of data about the residues. The evaluation of pesticide residues in food and environment samples is an important means to ensure food quality and protect consumers against potential dietary risks. Improper storage of pesticide residue samples may result in loss of pesticide and unreliable data, which could affect safety assessments.

RESULTS

The influences of storage conditions, including temperature (-20 °C, 4 °C, and ambient temperature) and sample state (homogenized state and coarsely chopped state) on the storage stability of dichlorvos, malathion, and diazinon on cowpea were studied. Dichlorvos and malathion were more stable in an homogenized state than in a coarsely chopped state. At 4 °C, the residual dichlorvos in the coarsely chopped state and the homogenized state, respectively, was 12% and 69%; the residual malathion was 26% and 92%, respectively. Dichlorvos suffered a large loss of 89% and 59% for coarsely chopped and homogenized cowpea, even at -20 °C. It was obvious that the stability of dichlorvos and malathion were more affected by storage state than diazinon. The stability of diazinon was significantly affected by temperature. The effect of storage state and temperature on stability is likely to be correlated with enzymes in the matrix, such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD).

CONCLUSION

The optimal stable storage conditions for three organophosphorus insecticides residues on cowpea were in the homogenized state and under a lower temperature. © 2021 Society of Chemical Industry.

Occurrence of pesticides and environmental contaminants in vineyards: Case study of Portuguese grapevine canes

Every year, after grape harvesting, high quantities of vine-canes are generated. Due to the high amount of bioactive compounds present in this woody material, several studies reported their potential to be used in different sustainable applications. However, before employing vine-canes in this kind of products, their safety needs to be assessed. A robust method for identification and quantification of 30 environmental contaminants (12 organochloride pesticides (OCPs), 6 organophosphorus pesticides (OPPs), 5 polychlorinated biphenyls (PCBs) and 7 brominated flame retardants (BFRs)) in vine-canes was developed. For that, the extraction and clean-up procedures were optimized, namely the vine-canes size, the QuEChERS (quick, easy, cheap, effective, rugged and safe) composition and the amount of carbon used in the dispersive-solid phase extraction (d-SPE). Suitable analytical parameters were obtained: linearity (r²) >0.99 for all the studied compounds and for the solvent and matrix-matched standards; relative standard deviation (RSD) below 14%; and mean recoveries for two spiking levels (10 and 20 μg/kg) between 75 and 103%, excepting for the PCBs that ranged between 59 and 105%. The limit of detection (LOD) and quantification (LOQ) ranged between 0.38 and 1.09 and 1.26 to 3.64 μg/kg, respectively. Regarding the analysis of 19 vine-cane samples, corresponding to four different varieties (Touriga Nacional, Tinta Roriz, Alvarinho, and Loureiro) collected in four different years in the North of Portugal, five contaminants (aldrin, 2,2-bis(4-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE), α-hexachlorocyclohexane (α-HCH), 2,4,4'-trichlorobiphenyl (PCB28), and 2,2',4,5,5'-pentachlorobiphenyl (PCB101)) were detected. However, only α-HCH (5.85 ± 0.32 to 5.99 ± 0.25 μg/kg) and aldrin (2.44 ± 0.15 μg/kg) were quantified above the LOQ. The screening of environmental contaminants in vine-canes is essential to waste valorization, especially if the goal is to apply them in products for human consumption.

A Method Scope Extension for the Simultaneous Analysis of POPs, Current-Use and Banned Pesticides, Rodenticides, and Pharmaceuticals in Liver. Application to Food Safety and Biomonitoring

The screening of hundreds of substances belonging to multiple chemical classes in liver is required in areas such as food safety or biomonitoring. We adapted a previous QuEChERS-based method in blood to the liver matrix and applied to these fields of study. The validation of the method allowed the inclusion of 351 contaminants, 80% with a LOQ < 2 ng/g. In the analysis of 42 consumer liver samples, we detected trace levels of 29 different contaminants. The most frequent and concentrated was 4,4’-DDE. POPs accounted for 66% of the compounds detected. In no case was the MRL reached for any of the contaminants detected. We also applied the method to 151 livers of wild birds to perform a biomonitoring pilot study in the Canary Islands. We detected 52 contaminants in 15 bird species. These were also mostly POPs, although high frequencies and concentrations of anticoagulant rodenticides (AR) and some other agricultural pesticides also stand out. POPs and AR contamination levels were significantly higher in terrestrial birds, raptors and particularly in nocturnal birds. Pesticide contamination levels were also higher in terrestrial birds, as well as in non-raptors and diurnal birds. The validated method is simple, robust, and sensitive and performs well in a variety of practical scenarios, where it can be carried out relatively quickly and inexpensively.

Polycyclic Aromatic Hydrocarbon Risk Assessment and Analytical Methods Using QuEchERS Pretreatment for the Evaluation of Herbal Medicine Ingredients in Korea

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic and mutagenic compounds that are often formed during the thermal processing of herbal medicine ingredients. In this study, the concentrations of four PAHs (PAH4) in various herbal medicine ingredients were monitored. Further, the QuEChERS method was used to replace conventional pretreatment, a more complex and cumbersome approach. The recovery range of the QuEChERS method ranged between 89.65–118.59%, and the average detection levels of benzo[a]anthracene (BaA), chrysene (CHR), benzo[b]fluoranthene (BbF), and Benzo[a]pyrene (BaP) in 50 herbal medicine ingredients were 0.18, 0.27, 1.13, and 0.17 μg/kg, respectively. The BaP and PAH4 levels in all tested samples were deemed safe according to risk characterization analyses based on European Union and Korean guidelines. Therefore, our findings indicated that the QuEChERS method could be used as an effective alternative to conventional sample pretreatment for the analysis of herbal medicine ingredients.

Enantiomeric profiling of mefentrifluconazole in watermelon across China: Enantiochemistry, environmental fate, storage stability, and comparative dietary risk assessment

Elucidating the enantiomeric chemistry and enantioselective fate of the novel chiral triazole fungicide mefentrifluconazole is of vital importance for agroecosystem safety and human health. The absolute configuration of mefentrifluconazole was identified firstly as S-(+)-mefentrifluconazole and R-(-)-mefentrifluconazole on a cellulose tris(3-chloro-4-methylphenylcarbamate) chiral phase. A baseline resolution (Rs, 2.51), favorable retention (RT ≤ 2.24 min), and high sensitivity (LOQ, 0.5 μg/kg) of enantiomer pair were achieved by reversed-phase liquid chromatography tandem mass spectrometry combined with a 3D response surface strategy. Nationwide field trials were undertaken to clarify the enantiomer occurrence, enantioselective dissipation, terminal concentrations, and storage stability of S-mefentrifluconazole and R-mefentrifluconazole in watermelon across China. The original deposition of the sum of enantiomer pair was estimated to be 14.4-163.7 μg/kg, and terminally decreased to < LOQ-59.3 μg/kg 10 days after foliage application. S-mefentrifluconazole preferentially degraded (T_1/2, 3.3-6.0 days), resulting in the relative enrichment of R-mefentrifluconazole (T_1/2, 3.9-6.6 days) in watermelon. A probabilistic model is recommended for the dietary risk assessment, although both acute (%ARfD, 0.435-22.188%) and chronic (%ADI, 1.697-9.658%) risks are acceptable for associated population. The long-term exposures should be continuously emphasized given the increasing applications and persistent fate of mefentrifluconazole, especially for urban children.

Terminal residue and dietary intake risk assessment of prothioconazole-desthio and fluoxastrobin in wheat field ecosystem

BACKGROUND

Wheat is one of the most important cereal crops worldwide, and use of fungicides is an essential part of wheat production. Both prothioconazole and fluoxastrobin give excellent control of important seed and soilborne pathogens. The combination of these two fungicides shows a complementary mode of action and has a wide usage around the world. But the residue levels of these fungicides in the wheat matrix are still unknown.

RESULTS

In the current study, a simple, low-cost and highly sensitive method using modified QuECHERS procedure combined with high-performance liquid chromatography-tandem mass spectrometry was developed to simultaneously quantify E- and Z-fluoxastrobin and the main metabolite prothioconazole-desthio of prothioconazole in the wheat matrix. The recoveries of prothioconazole-desthio, E-fluoxastrobin and Z-fluoxastrobin ranged from 84% to 101%, with relative standard deviation of less than 13.2%. The terminal residues of prothioconazole-desthio and E- and Z-fluoxastrobin were studied in wheat grain and straw under field conditions. The results showed that the terminal residue of the target compounds ranged from <0.01 to 0.029 mg kg^-1 and <0.05 to 7.6 mg kg^-1 in wheat grain and straw (expressed as dry weight), respectively. The risk quotients of prothioconazole-desthio and fluoxastrobin were 0.2% and 3.2%.

CONCLUSIONS

The residue levels of the target analytes in wheat grain were lower than the maximum residue limits recommended by the Chinese Ministry of Agriculture. And the calculated risk quotient values were far below 100%, indicating a low dietary intake health risk to consumers. © 2021 Society of Chemical Industry.

Validation of a Method Scope Extension for the Analysis of POPs in Soil and Verification in Organic and Conventional Farms of the Canary Islands

Persistent organic pollutants (POPs) are among the most relevant and dangerous contaminants in soil, from where they can be transferred to crops. Additionally, livestock animals may inadvertently consume relatively high amounts of soil attached to the roots of the vegetables while grazing, leading to indirect exposure to humans. Therefore, periodic monitoring of soils is crucial; thus, simple, robust, and powerful methods are needed. In this study, we have tested and validated an easy QuEChERS-based method for the extraction of 49 POPs (8 PBDEs, 12 OCPs, 11 PAHs, and 18 PCBs) in soils and their analysis by GC-MS/MS. The method was validated in terms of linearity, precision, and accuracy, and a matrix effect study was performed. The limits of detection (LOD) were established between 0.048 and 3.125 ng g⁻¹ and the limits of quantification (LOQ) were between 0.5 and 20 ng g⁻¹, except for naphthalene (50 ng g⁻¹). Then, to verify the applicability of the validated method, we applied it to a series of 81 soil samples from farms dedicated to mixed vegetable cultivation and vineyards in the Canary Islands, both from two modes of production (organic vs. conventional) where residues of OCPs, PCBs, and PAHs were found.

Dissipation kinetics and safety evaluation of pyraclostrobin and its desmethoxy metabolite BF 500-3 in a cucumber greenhouse agroecosystem

Pyraclostrobin (PYR), a fungicide of the strobilurin class, is used to control many different kinds of fungal diseases in greenhouses and on agricultural fields. In the present study, an efficient method was established for simultaneously determining PYR and its metabolite BF 500-3 in cucumber fruits, leaves, and soil matrices using QuEChERS pretreatment coupled with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The residue levels and dissipation kinetics of PYR were determined under greenhouse conditions. The recoveries ranged from 89.8 to 103.6% with relative standard deviations (RSDs) of 3.6-7.5% at three spiking levels. The results demonstrated that PYR dissipated quickly in the cucumber field with half-lives (DT₅₀) of 2.14-4.17 days on different sites and in different matrices. The residue of its metabolite BF 500-3 was very low and showed a trend of first increasing and then decreasing. The degradation rate of PYR in soil was the fastest, followed by that on cucumber fruits and leaves. The terminal residue of PYR at an application rate of 150 g a.i. ha^-1 (the maximum recommended rate) in cucumber fruits was below the maximum residue limit (MRL) of 0.5 mg/kg established in China. However, the application of the fungicide at 225 g a.i. ha^-1 (1.5× the maximum recommended rate) resulted in residues that were above the MRL 1 day after the final application, which is an unacceptable risk. Therefore, the application dosage of PYR at the recommended rates was safe to human beings and animals.

Overcoming difficulties in the evaluation of captan and folpet residues by supercritical fluid chromatography coupled to mass spectrometry

Serious difficulties in evaluating the fungicides captan and folpet by the usual chromatography systems coupled to mass spectrometry are well known. These compounds are highly prone to degradation due to different conditions into tetrahydrophthalimide (THPI) and phthalimide (PHI). Such an effect can be produced at different stages of the analytical procedure or during the growing crop, making their evaluation troublesome. As a consequence, the quantification of captan and folpet is typically performed through or together these metabolites. However, imide ring metabolites can be produced by other unknown sources, including other phthalimide derived pesticides enabling false positive results. For this reason, in the last decade, laboratories demand a robust method to quantify captan and folpet, that overcomes such a situation. In the present work, various operational parameters were optimized to ensure the no degradation of captan and folpet facilitated by supercritical fluid chromatography coupled to mass spectrometry (SFC-MS/MS). A direct comparison with reverse-phase LC-MS/MS and GC-MS/MS was conducted for comparative purposes. The representative commodities selected for this evaluation were pepper and tomato. Furthermore, possible oxidative degradation during the sample milling step was also evaluated and avoided by the application of crio-milling conditions and ascorbic acid addition. By the proposed procedure, captan and folpet were recovered in both matrices at the 84%-105% range and with an RSD below 8% at two concentration levels: 10 and 50 μg/kg. On the contrary, with GC-MS/MS, captan and folpet were not recovered, and, as a consequence, their evaluation was possible only by THPI and PI. In the case of LC-MS/MS a significant decrease in the sensitivity was observed compared to SFC-MS/MS. Other validation parameters evaluated were satisfactory. This new approach can assess the correct analysis of captan and folpet at low concentrations in fruits and vegetables.

Optimization and validation of a QuEChERS-based method for the simultaneous environmental monitoring of 218 pesticide residues in clay loam soil

A modified QuEChERS method was optimized, validated and verified for the extraction of 218 pesticide residues in agricultural soil samples. The 218 analytes are extracted using a single step, without clean-up, with matrix-matched calibration, and two complementary techniques: liquid and gas chromatography tandem triple quad mass spectrometry (LC-MS/MS and GC-MS/MS). Some of the parameters such as salts, acidity of the extraction solvent, sample moisture and some mechanical changes in the procedure were optimized to improve the overall performance for the target compounds and the soil matrix. The method was fully validated on a representative agricultural soil sample of the Canary Islands (clay loam soil) in terms of linearity, accuracy and precision. To avoid matrix effects, matrix-matched calibration curves (R² ≥ 0.99) were used for all target analytes. 100% of the compounds can be quantified with limits of quantification (LOQ) lower than the limit typically used in soils (50 ng g^-1), with 92% of compounds presenting a LOQ that is at least 10 times lower than that normally required. The limits of detection (LOD) ranged between 0.024 and 6.25 ng g^-1. The validated method was applied to a series of actual samples of agricultural soil (n = 18). In addition, as a further verification of its potential, the results of the application of the method in the investigation of clay loam soil samples that were obtained from underneath wildlife carcasses in the context of an environmental forensic investigation are also presented.

Development and validation of an analysis method for pesticide residues by gas chromatography-tandem mass spectrometry in Daikenchuto

Daikenchuto (DKT) is one of the most widely used “Kampo” in Japan as a representative of herbal medicine. Because DKT is made from a natural product like food, it requires the management of pesticides; therefore, an analysis of residual pesticides in Kampo is required. The World Health Organization (WHO) indicates that pesticide residue analysis by the U.S. Pharmacopeia (USP) is required. USP defines 107 compounds containing organochlorine pesticides and organophosphorus pesticides and their metabolites, which have a high residual risk. Accordingly, to guarantee the safety of herbal medicines according to global standards is a very important issue. In this study, we developed an analytical method for 91 compounds, which are listed in USP, using DKT as the subject. The method could extract pesticides from DKT with acetone, elute pesticides with acetonitrile using a SepPak C18 column (5 g) and with ethyl acetate using a DSC-NH₂ column (2 g), and perform simultaneous analyses by gas chromatography–tandem mass spectrometry (GC–MS/MS). This method, which could quantify 88 compounds, was validated according to USP. A pesticide residue analysis method that meets USP requirements enables the analysis of pesticide residues with a high residue risk and contributes to improving the safety of “Kampo” and other herbal medicines.

Customized dispersive micro-solid-phase extraction device combined with micro-desorption for the simultaneous determination of 39 multiclass pesticides in environmental water samples

A dispersive micro-solid phase extraction (d-µ-SPE) procedure was developed for the simultaneous extraction of 39 multiclass pesticides, containing a variety of chemical groups (organophosphate, organochlorine, pyrethroid, strobilurin, thiocarbamate, triazole, imidazole, and triazine), from water samples. A customized d-µ-SPE glass device was combined with a multi-tube platform vortex and a micro-desorption unit (Whatman Mini-UniPrep G2 syringeless filter), which allowed the unique simultaneous desorption, extract filtration, and injection. A simplex-centroid mixture design and Doehlert design were employed to optimize the extraction conditions. The optimized extraction conditions consisted of an extraction time of 30 min, an addition of 6.74 % of NaCl into 100 mL of water sample, and a desorption time of 24 min with 500 µL of EtAc. The procedure provided a low limit of detection (LOD), ranging from 0.51 ng L^-1 (4,4-DDE) to 22.4 ng L^-1 (dimethoate), and an enrichment factor ranging from 72.5 (dimethoate) to 200 (tebuconazole). The relative recoveries of the pesticides from spiked freshwater and seawater ranged from 74.2 % (endrin) to 123 % (molinate). The proposed procedure was applied to detect the presence of multiclass pesticides in environmental water samples. Three pesticides commonly applied in Brazil, namely, malathion, dimethoate, and lambda-cyhalothrin, were detected in concentrations ranging from <LOD to 120 ng L^-1 (dimethoate).

Critical review and re-assessment of analyte protectants in gas chromatography

Despite nearly 80 years of advancements in gas chromatography (GC), indirect chemical matrix effects (MEs), known as the matrix-induced response enhancement effect, still occur to cause a high bias in the GC analysis of susceptible analytes, unless precautions are taken. Matrix-matched calibration is one common option used in GC to compensate for the MEs, but this approach is usually inconvenient, imprecise, and inefficient. Other options, such as the method of standard additions, surface deactivation techniques, chemical derivatizations, priming the GC, and/or use of internal standards, also have flaws in practice. When methods are accommodating, the use of analyte protectants (APs) can provide the best practical solution to not only overcome MEs, but also to maximize analyte signal by increasing chromatographic and detection efficiencies for the analytes. APs address the source of MEs in every injection by filling active sites in the GC inlet, column, and detector, particularly in GC-MS, rather than the analytes that would otherwise undergo degradation, peak tailing, and/or diminished response due to interactions with the active sites. The addition of an adequate amount of APs (e.g. sugar derivatives) to all calibration standards and final extracts alike often leads to lower detection limits, better accuracy, narrower peaks, and greater robustness than the other options to compensate for MEs in GC. This article consists of a critical review of the scientific literature, proposal of mechanisms and theory, and re-evaluation studies involving APs for the first time in GC-orbitrap and GC-MS/MS with a high-efficiency ion source design. The findings showed that 1 µg each of co-injected shikimic acid and sorbitol in the former case, and 1 µg shikimic acid alone in the latter case, led to high quality results in multi-residue analysis of pesticides and environmental contaminants.

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.

Monitoring Organic Pollutants in Waters Using the Diffusive Gradients in the Thin Films Technique: Investigations on the Effects of Biofouling and Degradation

The diffusive gradients in thin films (DGT) passive sampling technique has been increasingly used to provide time-weighted average concentrations of the biorelevant fraction of organic contaminants in waters, with high spatial and temporal resolutions at low cost. This study was tested for the effects of biofouling and compound degradation/loss during sample handling/storage on the DGT measurement of a range of emerging organic pollutants. Biofouling was tested using biofilms collected from the influent and effluent of a typical urban wastewater treatment plant. Most (85%) target compounds showed no detectable effect on the DGT measurement when 8- and 15-day biofouled membrane filters were used. Four storage methods were designed to test for within-sampler degradation/loss for up to 2 months. Intact samplers can be simply stored in polyethylene bags at ambient temperature (18-26 °C) with most compounds stable (mass loss <20%) for at least 1 week. Keeping intact samplers at 4 °C or binding gels in solvent gave good recoveries, with most chemicals being stable for up to 2 months, although the best results were obtained when binding gels were kept in solvent at 4 °C. Recommendations are made for sample handling and storage of DGT samplers used for determination of trace organics in monitoring and surveillance campaigns.

Pesticide residues determination in common bean using an optimized QuEChERS approach followed by solvent exchange and GC-MS/MS analysis

BACKGROUND

Common bean is a staple food in Latin America and Africa; however, studies about contamination of common bean with pesticides are rarely reported. So, the goals of this study were to validate a multiresidue method and apply it in monitoring of pesticides in common beans. Extraction was performed applying the QuEChERS (quick, easy, cheap, effective, rugged, and safe) approach to ground samples. Octadecylsilane and primary-secondary amine were used for clean-up, and a solvent exchange step was performed before injection for gas chromatography-tandem mass spectrometry analysis. Method validation was done analyzing blank samples spiked at 20, 30, 50, and 100 μg kg^-1 (n = 5). Linearity and linear range were assessed by the analysis of standard solutions at concentrations of 5, 15, 25, 50, 75, 100, and 150 μg L^-1 .

RESULTS

The method was successfully validated for 91 (64.1%) of the 142 compounds studied (139 pesticides and three degradation products). Limits of quantification were equal to 20 μg kg^-1 , 30 μg kg^-1 , 50 μg kg^-1 , and 100 μg kg^-1 for 18 (12.7%), 17 (12.0%), 21 (14.8%) and 35 (24.6%) compounds respectively. Fifteen (10.6%) compounds were not detected at any level, and 36 (25.4%) did not fulfill the requirements for a quantitative method. Sixteen common bean samples of South of Brazil were analyzed. Two samples were positive: one for tebuconzole and a second for picoxystrobin, permethrin, and cyproconazole. Cyproconazole is not allowed for use in the common bean crop, its use being a violation.

CONCLUSION

As demonstrated, the validated approach is suitable for pesticide residues determination in common bean. Results of the sample analysis show that the control of pesticide residues in common bean is necessary to ensure food safety. © 2020 Society of Chemical Industry.

Assessment of Test Portion Sizes after Sample Comminution with Liquid Nitrogen in an Improved High-Throughput Method for Analysis of Pesticide Residues in Fruits and Vegetables

In this study, sample processing of bulk commodities using an efficient one-step comminution procedure with liquid nitrogen (LN₂) was devised and assessed in the analysis of pesticide residues in fruits and vegetables. LN₂ was added to the fresh samples from a tank by opening a valve, and the standard food chopper was kept in a laboratory hood to reduce safety risks. Test portions of four replicates each of 0.25, 0.5, 1, 2, 5, 10, and 15 g were taken from eight fruits and vegetables (tomato, squash, broccoli, apple, grape, peach, green bean, and cucumber) individually comminuted with LN₂. For comparison without comminution, similar test portions of a reconstituted freeze-dried certified reference material of pesticides in cucumber were also analyzed by the same method. More than 100 pesticides were monitored by both ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and instrument top sample preparation (ITSP) + fast low-pressure gas chromatography-tandem mass spectrometry (LPGC-MS/MS). A new version of QuEChERS-based sample preparation was followed, in which 5 mL of 4:1 (v/v) acetonitrile/water per gram of sample is used for extraction and 200 μL of initial extract is quickly evaporated, reconstituted in water, and ultracentrifuged for UHPLC-MS/MS analysis. For ITSP+LPGC-MS/MS, another portion of the initial extract undergoes salt-out partitioning with 4:1 (w/w) anhydrous MgSO₄/NaCl and the upper layer extract is transferred to an autosampler vial for automated cleanup and analysis in parallel. Quality control spikes were made during the comminution, extraction, cleanup, and analysis steps to isolate and estimate the individual and overall measurement uncertainties of the approach. The recommended test portion size is 2 g for routine monitoring by this approach, but results demonstrated that subsamples as low as 0.5 g typically gave overall biases and relative standard deviations of <10% for nearly all pesticides, commodities, and methods, which is 3-5% lower than previously evaluated sample processing and analytical methods. This approach can be used to improve data quality, laboratory efficiency, and sample throughput in routine monitoring programs for regulatory, risk assessment, and other purposes.

Method validation and dissipation kinetics of the new HPPD inhibitor QYR301 in rice, paddy water and paddy soil using a QuEChERS-based method and LC-MS/MS

A rapid and simple method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) of sample preparation using QuEChERS was developed for detecting residues of QYR301, a new HPPD-inhibiting herbicide, in rice plant (straw), water, soil, rice hull and brown rice (BR). To eliminate matrix interference, matrix-matched calibrations with satisfactory linearity (R² > 0.99) were used for accurate quantification. The method showed recoveries of 90.3-108.1% and relative standard deviations (RSDs) < 11%. The limits of quantification (LOQ) for QYR301 were 0.005 mg kg^-1 in all five matrixes. Furthermore, the dissipation kinetics and terminal residues of QYR301 were determined at two sites in 2018. The days for 50% dissipation (DT₅₀) of QYR301 in rice plants, water and soil were 3.6-4.4, 0.7-3.0 and 4.3-8.0 d, respectively, which indicated that QYR301 is a short-persistence herbicide. Moreover, no QYR301 residues were detected in BR, rice hull and straw collected at harvest following its application at 1.0 or 1.5 × of the recommended high rate. These results will help organizations and governments establish related principles/laws regarding the use of QYR301 in terms of environmental protection, food safety and other potential aspects.

Multi-residue analysis of captan, captafol, folpet, and iprodione in cereals using liquid chromatography with tandem mass spectrometry

In this study, we propose an improved analytical method for the multiresidue analysis of captan (plus its metabolite, tetrahydrophthalimide), folpet (plus its metabolite, phthalimide), captafol, and iprodione in cereals using liquid chromatography tandem mass spectrometry (LC-MS/MS). As captan, captafol, and folpet are easily degraded during homogenisation and extraction, samples were comminuted with liquid nitrogen, and both QuEChERS and ethyl acetate-based extraction workflows provided a satisfactory method performance. The optimised LC-MS/MS procedure with electrospray ionisation did not degrade these compounds, and offered sufficient method selectivity by resolving and minimising co-eluting matrix-derived interferences. The method also resolved the problem of non-specific mass spectra that these compounds usually produce on GC-MS analysis involving electron ionisation. The method performance was satisfactory for all 6 compounds at 0.01 mg kg^-1 and higher levels of fortification, and validated as per the SANTE/11813/2017 guidelines of analytical quality control in a wide range of cereals including rice, wheat, sorghum, and corn. The method provides special advantage of simultaneous analysis of captan, and folpet along with their metabolites (tetrahydrophthalimide, and phthalimide, respectively) in combination with captafol, and iprodione in a single chromatographic run. Although iprodione is known to degrade to 3,5-dichloroaniline, since this metabolite is not a part of the residue definition, it was not included in the scope of this method. As the method demonstrates satisfactory selectivity, sensitivity, accuracy, precision, and robustness in a wide range of cereal matrices, it is recommended for regulatory testing of these compounds in cereals.