Dissipation behavior, residue distribution and dietary risk assessment of chlorfenapyr and clothianidin in leek using RRLC-QqQ-MS/MS technique

Dissipation pattern and dietary risk assessment of chlorfenapyr and methomyl in corn under Egyptian field conditions

Corn is the second most widely farmed grain for human consumption. Low corn productivity due to damage caused by pests has led to using pesticides to control pest infestations. However, the uncontrolled application of pesticides on corn harms both environmental and human health. Accordingly, field experiments followed good agricultural practices to investigate the dissipation pattern and terminal residues of chlorfenapyr and methomyl in corn and compare the values with established safety limits. Gas chromatography-tandem mass spectrometer coupled with the quick, easy, cheap, effective, rugged, and safe technique was used to analyze residues of chlorfenapyr and methomyl in corn. The average recoveries varied from 94% to 105%, with relative standard deviations (RSDs) of 8%-13% for chlorfenapyr and from 99% to 111%, with RSDs of 10-16% for methomyl. Chlorfenapyr and methomyl residues degraded in corn following a first-order kinetic model, with an estimated half-life (t1/2) of 3.9 and 2.8 days, respectively, and significant degradation (91.4%-98.1.5%, respectively) after 14 days. Although the maximum residue limits of chlorfenapyr and methomyl for corn are yet to be formulated in Egypt, the long-term dietary risk for those pesticides was acceptable, with arisk quotient < 100%, according to the national assessments. These findings are required to guide the correct and safe application of these insecticides in Egypt.

The fate and potential hazards of chlorfenapyr and one metabolite tralopyril in cabbages: A comprehensive investigation

The potential hazards of chlorfenapyr warrant attention owing to its widespread application on vegetables. A comprehensive investigation of the fate of chlorfenapyr in the ecosystem is imperative. This paper presents a method for detecting chlorfenapyr and tralopyril in cabbages, which exhibits good linearity (determination coefficients > 0.99) and satisfactory recoveries (82.50 %-108.03 %). Chlorfenapyr residues in cabbages demonstrate a positive correlation with its application dose and time. Tralopyril can inhibit the dissipation of chlorfenapyr, as evidenced by the half-lives of 5.67-11.14 d (chlorfenapyr) and 6.91-14.77 d (total chlorfenapyr). The results of terminal residues (<2.0 mg/kg) and dietary risk assessment (<100 %) suggest preharvest intervals of 14 d (greenhouse) and 10 d (open-field). Additionally, the uptake of chlorfenapyr in cabbages is limited (translocation factor < 1), while the downward translocation predominantly occurs through phloem transport. The findings provide valuable insights for understanding the fate and potential risks of chlorfenapyr in cabbages.

Transport of neonicotinoid insecticides in a wetland ecosystem: Has the cultivation of different crops become the major sources?

Extensive application of neonicotinoid insecticides (NNIs) in agricultural production has resulted in widespread contamination of multiple environmental media. To investigate the occurrence and fate of NNIs in the largest marsh distribution area in Northeast China, an integrated ecosystem covering farmlands, rivers, and marshes, referred to as the farmland-river-marsh continuum in this study, was chosen for soil, water, and sediment sampling. Five NNIs were detected, with imidacloprid (IMI), thiamethoxam (THM), and clothianidin (CLO) being the most frequently detected ones in different samples. Concentrations of target NNIs in soil, surface water, and sediment samples were 2.23-136 ng/g dry weight (dw), 3.20-51.7 ng/L, and 1.53-8.40 ng/g dw, respectively. In soils, NNIs were detected more often and at higher concentrations in upland fields, while the concentration of NNIs in the soybean-growing soils (71.5 ng/g dw) was significantly higher than in the rice-growing soils (18.5 ng/g dw) (p < 0.05). Total concentration of NNIs in surface water was lower in the Qixing River channel than inside the marsh, while that in sediments showed an opposite trend. Total migration mass of IMI from approximately 157,000 ha of farmland soil by surface runoff was estimated to be 2636-3402 kg from the application time to the sampling period. The storage of NNIs in sediments was estimated to range from 45.9 to 252 ng/cm². The estimated environmental risks, calculated as the risk quotients (RQs), revealed low risks to aquatic organisms (RQs <0.1) from the residual concentrations of NNIs in water.

Residue analysis, dissipation patterns of chlorfenapyr, diafenthiuron and their corresponding metabolites in tea trees, and dietary intake risk assessment

BACKGROUND

Recently, chlorfenapyr and diafenthiuron have been widely used to prevent and control diseases and pests in tea production. However, rare studies have investigated the dissipation patterns of chlorfenapyr, diafenthiuron and their metabolites simultaneously in tea matrices. Here, we established an analytical method to investigate the degradation patterns of five target compounds in tea shoots and made tea samples. Moreover, the dietary intake risk assessment of chlorfenapyr-diafenthiuron mixture among Chinese populations was evaluated based on the supervised field experiment.

RESULTS

The mean recoveries of the primary analytes at five spiking levels were between 95.6% and 112.6% in tea shoots and made tea, respectively, and the values of RSD (relative standard deviation) were lower than 9.7% for all the target analytes. The field trial results showed that the half-lives of chlorfenapyr and diafenthiuron based on the residue definition were 10.0-12.4 days and 4.3-5.9 days, respectively, in tea shoots. For the dietary intake risk assessment, the risk quotient (RQ) values in made tea ranged from 30.4% to 73.9% at the pre-harvest interval of 14 days, which were significantly less than 100%.

CONCLUSION

The accuracy and precision of the developed method were satisfied by the measurement requirements according to the validation results. The dynamic dissipation experiments suggested that diafenthiuron was much easier to dissipate than chlorfenapyr. Moreover, the existence of tralopyril made the half-life of chlorfenapyr significantly increase, indicating that practical application of chlorfenapyr should take careful consideration of its metabolite. Finally, the potential chronic dietary risks of the chlorfenapyr-diafenthiuron mixture to human communities were within the acceptable range. © 2022 Society of Chemical Industry.

Dissipation rates, residue distribution, degradation products, and degradation pathway of sulfoxaflor in broccoli

Broccoli was selected as the research object in this paper to reveal the dissipation, distribution, and degradation pathway of sulfoxaflor under greenhouse and open-field cultivation conditions for the ecological risk assessment of sulfoxaflor. Results showed that the dissipation of sulfoxaflor in broccoli leaves, flowers, stems, roots, and the whole broccoli was in accordance with the first-order kinetic equation. The sulfoxaflor concentration in broccoli roots reached the maximum value after 1 day of application and then gradually decreased. The degradation half-lives of sulfoxaflor in the roots, leaves, flowers, stems, and whole broccoli were between 2.3 and 19.8 days. The longest degradation half-life of sulfoxaflor was in Heilongjiang under greenhouse cultivation. The terminal residue of sulfoxaflor in broccoli was in the range of 0.005-0.029 mg/kg, and the proportion of sulfoxaflor residue in broccoli leaves was the largest. Thirteen transformation products were separated and identified by ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry, and their kinetic evolution was studied. The cleavage of the N = S bond, C-S bond, C-O bond, and cyanide, as well as glucosylation, hydroxylation, SO extrusion, elimination, sulfhydrylation, ketonization, defluorination, and rearrangement, was inferred as the mechanism. Overall, these results can provide guidance for the supervision of the safe application of sulfoxaflor.

Determination of Market, Field Samples, and Dietary Risk Assessment of Chlorfenapyr and Tralopyril in 16 Crops

The frequent and massive use of chlorfenapyr has led to pesticide residues in crops, threatening food safety and human health. However, there is limited research on the detection of tralopyril, which is the major metabolite of chlorfenapyr with high toxicity. This study aimed to develop a novel, sensitive, and highly efficient method for the determination of chlorfenapyr and tralopyril residues in 16 crops. The optimized purification procedure provided satisfactory recovery of 76.6-110%, with relative standard deviations of 1.3-11.1%. The quantification values of pesticides in crop matrixes were all 0.01 μg kg^-1. The optimal method was adopted to determine the chlorfenapyr and tralopyril residues in field trials in 12 regions in China and monitor their residues in 16 agricultural products. The results of the dissipation and terminal residue experiments show that the final residue of chlorfenapyr was less than MRL (maximum residue limit) and no tralopyril was detected in the field samples. Moreover, the qualification proportion of these residues in market samples were up to 99.5%. The RQ (risk quotient) values of chlorfenapyr and chlorfenapyr with consideration of tralopyril were both apparently lower than an RQ of 100%, indicating an acceptable level. This research provides a thorough long-term dietary risk evaluation on chlorfenapyr and tralopyril and would provide reference for their scientific and safe utilization.

Dissipation behaviour, residue analysis, and dietary safety evaluation of chlorfenapyr on various vegetables in China

Chlorfenapyr has been widely used in recent years to control a variety of pests on fruit and vegetables. Cabbage, leek, asparagus, and chive are four of the most common green foods consumed word wide; their pesticide residue issues have also received more attention. Therefore, studies on the residue analysis, degradation evaluation and dietary risk assessment based on the complete residue definition of chlorfenapyr on these four vegetables were essential and urgently needed. A reliable analytical method was developed and applied to simultaneously determine the content of chlorfenapyr and its metabolite tralopyril residues on the four vegetables. Recoveries were satisfactory (84%-110% for chlorfenapyr; 83%-106% for tralopyril) at a spiked level of 0.01-1 mg/kg, with intraday precision (n = 5) and interday precision (n = 15) ranging from 1.6% to 8.9% and from 2.4% to 9.1%, respectively. The limits of quantification (LOQs) were all 0.01 mg/kg. On the basis of supervised field trials, the degradation half-lives of chlorfenapyr were 1.2-9.8 days. Chlorfenapyr rapidly degraded on asparagus, but persisted much longer on chive. The terminal concentration of chlorfenapyr residues varied from <0.01 to 0.84 mg/kg. Additionally, the risk quotients (RQs) ranged from 4.7% to 13.8%, suggesting that chlorfenapyr had a negligible risk for chronic dietary intake of these crops. This study was thus significant in evaluating the degradation rate and quality safety of chlorfenapyr on various vegetables and promoted the development of maximum residue limits.

Residual levels and dietary risk assessment of bifenthrin and dinotefuran and its major metabolites in open wheat field conditions

To evaluate the residual levels of bifenthrin and dinotefuran, a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) and high-performance liquid chromatography-tandem mass spectrometry method for simultaneous detection of bifenthrin and dinotefuran and its major metabolites in wheat was developed and validated. Dietary risk assessments were further performed based on the relevant residual data from 12 wheat fields, toxicology data and dietary patterns. In wheat grain and straw, the recoveries of all analytes ranged from 77 to 102% with the relative standard deviation <9.7% and the limit of quantitation 0.05 mg kg^-1 . The highest terminal residue of bifenthrin in wheat grain was 0.069 mg kg^-1 and dinotefuran was 0.34 mg kg^-1 . Residual concentrations of bifenthrin and dinotefuran decreased to <0.05 and 0.15 mg kg^-1 at 21 days (pre-harvest interval), respectively. The chronic risk quotient ranged from 6.4 to 62.7% and the acute risk quotient varied from 0.38 to 17.73%. The chronic and acute dietary risks caused by the terminal residues of the two insecticides were negligible for Chinese populations. The recommended pre-harvest interval was proposed to ensure safe wheat consumption. These data could provide a scientific reference to establish the Chinese maximum residue limit of dinotefuran in wheat.

Pesticide Residue Behavior and Risk Assessment in Celery after Se Nanoparticles Application

This study investigates pesticide levels in celery, and compares their degradation, dissipation, distribution, and dietary risk after spraying with selenium (Se) nanoparticles. Abamectin, imidacloprid, acetamiprid, thiamethoxam, and lambda-cyhalothrin were sprayed at 1.6, 6.8, 2.0, 1.0, and 0.7 g a.i. ha⁻¹ followed by a 2 g·ha⁻¹ Se nanoparticle application during the growing period. Thiamethoxam, abamectin, imidacloprid, lambda-cyhalothrin, and acetamiprid in celery degraded following a first order kinetic model after 2 g·ha⁻¹ Se nanoparticles application. With the exception of acetamiprid, the half-lives of thiamethoxam, abamectin, imidacloprid, and lambda-cyhalothrin were reduced from 2.4, 0.5, 1.2, 4.2 days without Se nanoparticles application to 1.4, 0.2, 0.9, 3.7 days with the addition of Se nanoparticles (2 g·ha⁻¹), respectively. The chronic dietary exposure risk probability (RQc) and the acute dietary exposure risk probability (RQa) of celery after Se nanoparticles application were within acceptable limits for consumption except for abamectin.

Dissipation, residue, dietary, and ecological risk assessment of atrazine in apples, grapes, tea, and their soil

Atrazine is one of the most used herbicides in China. It is a persistent organic pollutant but has been widely used on Chinese farmlands for a long time. To assess its dietary and ecological risks to human and environment, in this study, atrazine residues were extracted with acetonitrile and then plant samples were detected with gas chromatography coupled with mass spectrometry (GC-MS) and soil samples were determined with gas chromatography coupled with nitrogen-phosphorus detector (GC-NPD). The limit of quantification (LOQ) of the method was 0.01 mg/kg for all matrices. The recoveries ranged from 82.0 to 105.4% for plant samples and 75.6 to 85.6% for soil samples. The final residues of atrazine in all plant samples were lower than LOQ. Dietary risk assessment suggested that under good agricultural practices (GAP) conditions, intake of atrazine from apples, grapes, and tea would exhibit an acceptably low health risk on consumers. However, the final residues of atrazine in soil samples were <0.01-9.2 mg/kg, and the half-lives were 2.0-9.1 days. Based on the species sensitivity distribution (SSD) model, the potential affected fraction (PAF) of atrazine in soil samples ranges from 0.01 to 65.8%. Atrazine residues in 43.1% soil samples were higher than 0.11 mg/kg, which was the hazardous concentration for 5% of species (HC₅) of atrazine in soil. These results suggested that the ecological risks of atrazine in apples, grapes, and tea garden soil would exhibit a high risk on environmental species even under the same GAP conditions. This study could provide guidance for comprehensive risk assessment of atrazine properly used in apple, grape, and tea gardens.

Dissipation, residues and risk assessment of pyraclostrobin and picoxystrobin in cucumber under field conditions

BACKGROUND

Pyraclostrobin and picoxystrobin are two representative pesticides of strobilurins used to treat cucumber downy mildew, which have raised issues of food safety and human health. A new formulation containing these two compounds is being prepared for marketing in China.

RESULTS

The dissipation and residual levels of pyraclostrobin and picoxystrobin in cucumbers under field conditions were determined simultaneously by a validated method via liquid chromatography-tandem mass spectrometry (LC-MS/MS). The dissipation rules were described by first-order kinetics and the half-lives of pyraclostrobin and picoxystrobin were less than 8.2 days and 3.4 days. The highest terminal residue of pyraclostrobin was 0.014 mg kg^-1 which was lower than maximum residue limit (MRL) in China (0.5 mg kg^-1 ) and of picoxystrobin was 0.029 mg kg^-1 , respectively. In the long-term intake risk assessment of pyraclostrobin and picoxystrobin for general population (18-79 years), the chronic risk quotient (RQ_c ) varied from 5.64% to 21.97%. The assessment of short-term risks included children (1-6 years) and adults (18-79 years) and in which the RQ_a values were 0.38% and 2.85%. Both results showed the intake risks of cucumber were acceptable.

CONCLUSION

Pyraclostrobin and picoxystrobin degraded easily in cucumbers under open field conditions. The long-term and short-term risks caused by final residues of pyraclostrobin and picoxystrobin were insignificant. The recommended pre-harvest interval of 3 days was safe. The article will be helpful in rational use of these pesticides and MRL formulation of picoxystrobin on cucumber. © 2020 Society of Chemical Industry.

Dissipation and dietary risk assessment of kasugamycin and saisentong in Chinese cabbage

A quick, easy, cheap, effective, rugged, and safe pretreatment method using dispersive solid-phase extraction was developed to quantify kasugamycin in Chinese cabbage samples by using ultra-performance liquid chromatography/tandem mass spectrometry. A pretreatment method involving precolumn transformation was utilized to determine the residue of saisentong in Chinese cabbage through high-performance liquid chromatography/ultraviolet detection. These methods were successfully applied through field trials to determine the contents of kasugamycin and saisentong in Chinese cabbage. The dissipation of kasugamycin and saisentong in Chinese cabbage followed first-order kinetics with a linear correlation coefficient of 0.9066-0.9731 at the 95% confidence level. The half-lives of kasugamycin and saisentong in Chinese cabbage were 1.8-2.0 and 2.2-3.8 days, respectively. Terminal residual levels of kasugamycin in Chinese cabbage were not detected 14 days after application. The dietary risk assessment of kasugamycin and saisentong in Chinese cabbage showed that their risk quotients were 0.93 and 2.58%, respectively, in the preharvest interval (PHI) of 14 days. Kasugamycin and saisentong in Chinese cabbage did not pose potential health hazards at PHI of 14 days. The maximum residue limits of kasugamycin and saisentong in Chinese cabbage were 0.02 and 0.36 mg/kg, respectively, and 14 days was the safe PHI.

Residues and Dietary Risk Assessments of 2,4-D Isooctyl Ester, Metribuzin, Acetochlor, and 2-Ethyl-6-methylaniline in Corn or Soybean Fields

Since 2,4-dichlorophenoxy acetic acid (2,4-D) was discovered in the 1940s, 2,4-D and its derivatives remain among most commonly used herbicides in the world. There have been recent increases in using 2,4-D products in a combination with other herbicides such as metribuzin and acetochlor to control noxious weeds. However, accurate analysis of 2,4-D isooctyl ester remains to be improved due to long analysis time and rapid conversion of the ester to acid (i.e., under-reporting residues). In this work, a simple hydrolysis procedure was introduced to provide a quantitative hydrolytic rate of the ester (>95%) and did not affect the other pH-sensitive compounds. Analysis parameters and sample pretreatments were optimized for improved selectivity and accuracy. The hydrolysis-QuEChERS (quick, easy, cheap, effective, rugged, and safe) technique for multidetermination of 2,4-D isooctyl ester, metribuzin, acetochlor, and 2-ethyl-6-methylaniline in corn and soybeans via high performance liquid chromatography-tandem mass spectrometry was established. The method had average recoveries of 74-109% with relative standard deviations ≤13.5% and limits of quantifications (LOQs) of 0.05 mg/kg. The terminal residues of these compounds found in real edible matrixes were less than the corresponding LOQs at harvest time. The risk quotients were far below 100%, indicating a low health risk to consumers.