Persistence behaviour of deltamethrin on tea and its transfer from processed tea to infusion

Dissipation behaviors of deltamethrin, emamectin benzoate and hexythiazox in grape under field conditions

The objective of this study was to evaluate the dissipation kinetics of deltamethrin, emamectin benzoate, and hexythiazox in grapes. The QuEChERS method was employed and validated for the precise determination of these three pesticides using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Excellent linearity was observed with regression coefficients exceeding 0.998. Notably, the limits of quantification (LOQ) were significantly lower than the maximum residue limits (MRLs) established for grapes by the European Union. The QuEChERS method l recovered 93.23% of the pesticides with an acceptable RSD of 5.35% (n = 180), demonstrating its suitability for quantifying them in grapes. Half-lives of deltamethrin, emamectin benzoate, and hexythiazox in grapes were 2.62-2.68 days, 8.15-7.30 days, and 3.24-4.01 days, respectively, for both single and double doses. Residues of all pesticides fell below the MRLs by the preharvest interval. This suggests that their application can be considered safe for grapes, ensuring both pest control and consumer safety.

Detection methods, migration patterns, and health effects of pesticide residues in tea

Due to its rich health benefits and unique cultural charm, tea drinking is increasingly popular with the public in modern society. The safety of tea is the top priority that affects the development of tea industry and the health of consumers. During the process of tea growth, pesticides are used to prevent the invasion of pests and diseases with maintaining high quality and stable yield. Because hot water brewing is the traditional way of tea consumption, water is the main carrier for pesticide residues in tea into human body accompanied by potential risks. In this review, pesticides used in tea gardens are divided into two categories according to their solubility, among which water-soluble pesticides pose a greater risk. We summarized the methods of the sample pretreatment and detection of pesticide residues and expounded the migration patterns and influencing factors of tea throughout the process of growth, processing, storage, and consumption. Moreover, the toxicity and safety of pesticide residues and diseases caused by human intake were analyzed. The risk assessment and traceability of pesticide residues in tea were carried out, and potential eco-friendly improvement strategies were proposed. The review is expected to provide a valuable reference for reducing risks of pesticide residues in tea and ensuring the safety of tea consumption.

Chitosan nanoparticles modified TLC-densitometry for determination of imidacloprid and deltamethrin residues in plants: greenness assessment

Two thin layer chromatography (TLC) methods have been developed for the determination of pesticides residues of imidacloprid (IMD) and deltamethrin (DLM) in thyme and guava leaves. In the two methods, the used stationary phase was silica gel 60 F₂₅₄ plates impregnated in chitosan nanoparticles (ChTNPs) 0.5% to improve separation using a green developing system consists of isopropyl alcohol for IMD and n-hexane-toluene-ethylacetate for DLM. The two pesticides were determined quantitatively, after TLC separation, at wavelengths 270.0 nm for IMD and 230.0 nm for DLM. Validation of both approaches was carried out in agreement with the guidelines of International Conference on Harmonization (ICH) and found to be selective, reliable and reproducible. Limits of detection of IMD and DLM were 0.002 and 0.00116 μg/spot, respectively. The newly developed TLC methods were used to monitor the pre-harvest interval estimation. Analytical eco-scaling depending on penalty points for IMD was calculated and showed that this method was eco-friendlier than the reported one.

Dissipation kinetics of some pesticides applied singly or in mixtures in/on grape leaf

BACKGROUND

Grape and leaf quality are often severely reduced by fungi such as grey rot Botrytis cinerea Pers., powdery mildew Erysiphe necator Schwein, and downy mildew Plasmopara viticola (Berk. & M.A.Curtis) Berl. & De Toni and by insects such as Otiorhynchus spp., European grapevine moth Lobesia botrana Den.-Schiff., vine mealybug Planococcus citri Risso, and grape erineum mite Colomerus vitis Pgst. Various pesticides are often applied to mitigate these pest problems. These chemicals used singly as well as in the form of a mixture can leave residues on or in the crop. It is therefore of great importance to study the dissipation of the pesticides applied alone and in mixtures to this crop to protect consumers.

RESULTS

The dissipation kinetics of cypermethrin, boscalid, deltamethrin, kresoxim-methyl, lambda-cyhalothrin, metalaxyl-M, metrafenone, and triadimenol residues were studied in vine leaves grown under sunny conditions in Turkey. The dissipation rate for singly applied pesticides followed first-order kinetics, with half-lifes in grape leaves in the range of 1.85-7.22 days. Changes in the degradation process of pesticide residues were determined after application, as both single applications and mixtures. The degradation of boscalid, cymoxanil, deltamethrin and metalaxyl-M accelerated while the degradation of cypermethrin, kresoxim-methyl, and lambda-cyhalothrin slowed down in mixtures of pesticides.

CONCLUSION

The use of pesticides in mixtures leads to slower degradation and higher residues for some active ingredients and faster degradation and fewer residues for other active ingredients. Therefore, pesticide mixtures should not be applied in the field without having detailed information about their ingredients. © 2022 Society of Chemical Industry.

Residue pattern of chlorpyrifos and its metabolite in tea from cultivation to consumption

BACKGROUND

Chlorpyrifos (CPF) is a broad-spectrum organophosphorus pesticide widely used to control tea geometrid (Ectropis oblique) and tea green leafhoppers (Empoasca pirisuga Matsumura) in tea trees. The major metabolite of CPF in water, plants, and animals is 3,5,6-trichloro-2-pyridinol, which is more toxic than CPF. However, the dissipation pattern of CPF in tea is unknown.

RESULTS

An optimized QuEChERS sample preparation method combined with ultra-performance liquid chromatography-tandem mass spectrometry was applied to determine the residues of chlorpyrifos and its metabolite in tea during tea planting and green tea processing. During tea planting, the sum of chlorpyrifos and its metabolite dissipated rapidly with a half-life of 1.93 days for tea shoots. The residues of chlorpyrifos and its metabolite in made green tea were 96.89 and 35.88 μg kg^-1 on the seventh day. The values for processing factors of chlorpyrifos and its metabolite were all less than 1, showing that each green tea manufacturing step was responsible for the reduction. The transfer rates of chlorpyrifos and its metabolite from made green tea to its infusion were 0.68-4.62% and 62.93-71.79%, respectively.

CONCLUSION

The risk of chlorpyrifos was negligible to human health based on the hazard quotient, which was 7.4%. This study provides information relevant to the reasonable application of chlorpyrifos in tea planting and is potentially helpful for tea exporting and importing countries to establish harmonized maximum residue limits. © 2020 Society of Chemical Industry.

The degradation and metabolism of chlorfluazuron and flonicamid in tea: A risk assessment from tea garden to cup

Degradation and metabolism of chlorfluazuron and flonicamid from tea garden to cup were simultaneously investigated by a modified QuEChERS method coupled with UPLC-MS/MS quantification. The dissipation half-lives of chlorfluazuron, flonicamid, and total flonicamid (the sum of flonicamid and its metabolites TFNG, TFNA, and TFNA-AM) in fresh tea leaves during tea growth were 6.0 d, 4.8 d, and 8.1 d, respectively. TFNG and TFNA were generated during tea growth. After tea processing, the residues of chlorfluazuron, flonicamid, and its metabolites in black tea were higher than those in green tea. The average processing factors of chlorfluazuron, flonicamid, and total flonicamid in black tea were 2.54, 3.02, and 2.87, respectively, while in green tea they were 2.40, 2.93, and 2.79, respectively. TFNG, TFNA, and TFNA-AM were formed rapidly during the drying step. Considering the influence of water content at various processing steps, the average loss rates of chlorfluazuron, flonicamid, and total flonicamid residue from fresh tea leaves to black tea were 16.7%, 33.8%, and 20.7%, respectively, and 29.6%, 14.0% and 18.2%, respectively, in the case of green tea. The highest leaching rates of chlorfluazuron, flonicamid, and total flonicamid during tea brewing were 6.8%, 97.0%, and 97.4%, respectively, in black tea infusion, and 6.0%, 98.9%, and 98.6%, respectively, in green tea infusion. The metabolites, especially TFNG, had a higher leaching rate during tea brewing. The migration of chlorfluazuron from fresh leaves to tea infusion was low, and the migration of flonicamid was high. The RQc and RQa of chlorfluazuron and total flonicamid were less than 1. This result indicates that the potential dietary intake risk of chlorfluazuron from tea is negligible. However, the risk of total flonicamid intake is three times higher than that of chlorfluazuron. There is a potential risk of intake of flonicamid and its metabolites in tea for human consumption.

Dissipation, Processing, Leaching, and Safety Evaluation of Flonicamid and Its Metabolites in Tea

BACKGROUND

Tea is a popular traditional non-alcoholic beverage worldwide. Flonicamid is a selective systemic pyridine carboxamide insecticide that is widely used for controlling tea leafhopper in tea.

OBJECTIVE

The leaching rates, dissipation dynamics, and residue levels of flonicamid and its metabolites in tea leaves during processing and transferring were investigated to validate the safe risk in tea and transfer behavior using high performance liquid chromatography-tandem mass spectrometry with a convenient pretreatment method.

METHOD

The extracting method and immersion rate experiments were optimized by single factor analysis and orthogonal tests. The acetonitrile extracting solvent with 0.5% formic acid was used and optimal leaching conditions were obtained with a regime of 15 min immersion time, 100°C temperature, three immersions and a tea-to-water ratio of 1:50.

RESULTS

Average recoveries in processed green tea and infusions were 80.85-98.75% with relative standard deviations <5.87%. LODs and LOQs of flonicamid, 4-trifluoromethylnicotinic acid (TFNA), N-(4-trifluoromethylnicotinoyl) glycine (TFNG), and 4-trifluoromethylnicotinamide (TFNA-AM) were 0.0013-0.350 and 0.004-1 μg/g, respectively. The processing factor of flonicamid was 0.36-5.52 during green tea manufacture. The leaching rates were 22.9-97.4% from processed tea to infusion.

CONCLUSIONS

The risk of long-term and short-term dietary intake of flonicamid was safe in tea infusions with the risk quotient (RQ) values <1 for the Chinese consumer. This work may provide guidance for safe and reasonable consumption of flonicamid in tea in China.

HIGHLIGHTS

The suitable leaching factors of flonicamid and its metabolites in tea infusions were optimized by orthogonal experimentation for the first time.

Dissipation kinetics, dietary and ecological risk assessment of chlorantraniliprole residue in/on tomato and soil using GC-MS

An alternate single quadrupole gas chromatography coupled with electron ionization mass spectrometry (GC-EI-MS) method was developed and validated for the determination chlorantraniliprole residue in tomato and soil. The target analyte was extracted from selected matrices with acetonitrile followed by dispersive solid-phase extraction clean up with primary secondary amine and graphitized carbon black sorbent to remove co-extractives prior to analysis. Limit of quantification of the method was 0.01 μg/g and the recovery of chlorantraniliprole was in the range of 92-99% with RSD of less than 3%. The dissipation kinetics of chlorantraniliprole in tomato and soil followed first-order kinetics with the half-life of 1.26 and 1.77 days, respectively. A safe waiting period of 1 day suggested for safe consumption of tomato fruits considering the FSSAI maximum residue limit of 0.6 μg/g. The residue concentrations were reduced in the range of 13 to 64% from tomato fruit using simple household approaches. The present study suggested that the use of chlorantraniliprole in tomato does not seem to pose any dietary risk to consumers. The ecological risk quotient (RQ) values indicated that the chlorantraniliprole residues in the soil may pose a medium level of risk to earthworms and arthropods during this period.

Persistence, dietary and ecological risk assessment of indoxacarb residue in/on tomato and soil using GC-MS

An efficient single quadrupole gas chromatography with mass spectrometry method was developed and validated for the determination of indoxacarb residues in tomato and soil. Residues were extracted from the samples using acetonitrile as extracting solvent and the extracts were purified through primary secondary amine and graphitized carbon black. Recoveries were obtained in the range of 92.12-110.51% with the relative standard deviation of 1.32-4.32%. Indoxacarb dissipated with half-life of 3.12-3.21 and 1.24-1.35d for tomato and soil, respectively following doses of indoxacarb 14.5% SC at 60, 90 and 120 g.a.i./ha. Safe waiting periods were found to be 1-3d. The residues were removed from tomato fruit was in the range of 16.73 to 54.32% using simple decontamination approaches. The present study suggest that the use of indoxacarb in tomato at recommended dose, does not seem to pose any dietary risk to the consumers. The soil RQ values indicated low level of risk to earthworms and arthropods.

United States Pharmacopeia (USP) comprehensive review of the hepatotoxicity of green tea extracts

As part of the United States Pharmacopeia's ongoing review of dietary supplement safety data, a new comprehensive systematic review on green tea extracts (GTE) has been completed. GTEs may contain hepatotoxic solvent residues, pesticide residues, pyrrolizidine alkaloids and elemental impurities, but no evidence of their involvement in GTE-induced liver injury was found during this review. GTE catechin profiles vary significantly with manufacturing processes. Animal and human data indicate that repeated oral administration of bolus doses of GTE during fasting significantly increases bioavailability of catechins, specifically EGCG, possibly involving saturation of first-pass elimination mechanisms. Toxicological studies show a hepatocellular pattern of liver injury. Published adverse event case reports associate hepatotoxicity with EGCG intake amounts from 140 mg to ∼1000 mg/day and substantial inter-individual variability in susceptibility, possibly due to genetic factors. Based on these findings, USP included a cautionary labeling requirement in its Powdered Decaffeinated Green Tea Extract monograph that reads as follows: "Do not take on an empty stomach. Take with food. Do not use if you have a liver problem and discontinue use and consult a healthcare practitioner if you develop symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice (yellowing of the skin or eyes)."

Index design and safety evaluation of pesticides application based on a fuzzy AHP model for beverage crops: tea as a case study

BACKGROUND

A fuzzy analytic hierarchy process (AHP) is shown to be an effective methodology for multiple criteria decision-making from various heterogeneous data. Despite application of AHP to some decision-making problems in agriculture, research on AHP utilization for screening the safe use of pesticides for tea plantations based upon multiple criteria has not been reported. The overall safety chain from tea plantation to tea manufacture to tea cup after pesticides had been sprayed on a tea plantation was considered and the AHP network was constructed at two levels with two categories, tea-related parameters and pesticide toxicity. Seven criteria were selected as safety indexes, half-lives of pesticides on the tea plant (T_1/2 ), water solubility (Ws), vapor pressure (Vp), acceptable daily intake (ADI), acute oral lethal dose of pesticides to rat (LD₅₀ ), and ecotoxicity of pesticides including LD₅₀ to bees and LD₅₀ to aquatic organisms.

RESULTS

According to the AHP, water solubility was the most important factor in the evaluation pesticide safety for use on a tea plantation, followed by the half-lives of the pesticides on the tea plant and the acceptable daily intake. Combined with the scale of seven criteria and relative weight (W), 48 pesticides with an overall score (S) < 25 could be regarded as relatively safe compounds when applied in tea plantations.

CONCLUSION

An AHP approach was suggested to evaluate the safe use of pesticides on tea plantations. This study provides a new idea for the evaluation of safety in beverage crops. © 2019 Society of Chemical Industry.

Tracking residual organochlorine pesticides (OCPs) in green, herbal, and black tea leaves and infusions of commercially available tea products marketed in Poland

The content of residual organochlorine pesticides (OCPs) was examined in green, herbal, and black tea leaves as well as in their infusions prepared from tea products marketed in the main supermarkets in Poland. It was found that the detected mean levels of organochlorine residues in tea leaves ranged from <LOD to 16.36 ng g^-1 dry weight. Among hexachlorocyclohexane isomers, γ-HCH in green tea occurred in the highest concentrations. Among dichlorodiphenyltrichloroethane (DDT) metabolites the highest level of p,p'DDT (1.96 ng g^-1 dw) was in green tea samples. The transfer of OCPs from tea leaves to brew was investigated. The present study revealed that during the infusion process, a significant percentage of the residues, particularly pesticides with high water solubility, were transferred to the infusions. The obtained results show that the percentage transfer of each pesticides from tea to the tea infusions ranged from 6.74% (heptachlor) to 86.6% (endrin). The detected residues were below current MRLs for these pesticides.

Dissipation kinetics of beta-cyfluthrin and imidacloprid in tea and their transfer from processed tea to infusion

Dissipation kinetics of mixed formulation consisting beta-cyfluthrin and imidacloprid in tea crop under an open field ecosystem was investigated. The mixed formulation was applied on tea plant at recommended (27 + 63) and double the recommended (54 + 126g a.i./ha) dose and residues were determined using gas chromatography-electron capture detector and high performance liquid chromatography-photodiode array detector for beta-cyfluthrin and imidacloprid, respectively. The limit of quantification of analytical method was 0.05µg/g and the average recoveries were ranged from 88.36% to 103.49% with relative standard deviations of less than 6% at three spiked levels. The experimental results showed that in the green tea leaves imidacloprid dissipated faster than beta-cyfluthrin with the half-life ranging between 1.20-1.39 and 2.89-3.15days, respectively. The beta-cyfluthrin residues present in the processed tea not transferred into the tea infusion during the infusion process and imidacloprid transferred in the range 43.12-49.7%. On the basis of the transfer of residues from processed tea to infusion, a waiting period of 17 days for tea plucking after pesticide application at recommended dose may be suggested.

Factors Affecting Transfer of Pyrethroid Residues from Herbal Teas to Infusion and Influence of Physicochemical Properties of Pesticides

The transfer of pesticide residues from herbal teas to their infusion is a subject of particular interest. In this study, a multi-residue analytical method for the determination of pyrethroids (fenpropathrin, beta-cypermethrin, lambda-cyhalothrin, and fenvalerate) in honeysuckle, chrysanthemum, wolfberry, and licorice and their infusion samples was validated. The transfer of pyrethroid residues from tea to infusion was investigated at different water temperatures, tea/water ratios, and infusion intervals/times. The results show that low amounts (0-6.70%) of pyrethroids were transferred under the different tea brewing conditions examined, indicating that the infusion process reduced the pyrethroid content in the extracted liquid by over 90%. Similar results were obtained for the different tea varieties, and pesticides with high water solubility and low octanol-water partition coefficients (log K_ow) exhibited high transfer rates. Moreover, the estimated values of the exposure risk to the pyrethroids were in the range of 0.0022-0.33, indicating that the daily intake of the four pyrethroid residues from herbal tea can be regarded as safe. The present results can support the identification of suitable tea brewing conditions for significantly reducing the pesticide residue levels in the infusion.

Dissipation behavior of octachlorodipropyl ether residues during tea planting and brewing process

The dissipation behavior of octachlorodipropyl ether (OCDPE) residues in fresh tea shoots and in tea prepared under field conditions was investigated, and the transfer of residues from brewed tea to tea infusion was determined. OCDPE levels in tea shoots, prepared tea, tea infusion, and spent tea leaves were determined using a sensitive and simple method. The dissipation of OCDPE is fairly slow in tea shoots and prepared tea, with half-life values of 5.10 and 5.46 days, respectively. The degradation rates of OCDPE residues in tea processing were 23.9-43.1 %. The terminal residues of OCDPE in tea shoots and prepared tea samples after 20 and 30 days of OCDPE application were higher than 0.01 mg/kg. However, OCDPE's transfer rates from brewed tea to tea infusion were only 6.0-14.8 %. Further studies on risk assessment of OCDPE residue in tea on the basis of the relationship of OCDPE in prepared tea and infusion are warranted.

Dissipation Pattern, Processing Factors, and Safety Evaluation for Dimethoate and Its Metabolite (Omethoate) in Tea (Camellia Sinensis)

Residue levels of dimethoate and its oxon metabolite (omethoate) during tea planting, manufacturing, and brewing were investigated using a modified QuEChERS sample preparation and gas chromatography. Dissipation of dimethoate and its metabolite in tea plantation followed the first-order kinetic with a half-life of 1.08-1.27 d. Tea manufacturing has positive effects on dimethoate dissipation. Processing factors of dimethoate are in the range of 2.11-2.41 and 1.41-1.70 during green tea and black tea manufacturing, respectively. Omethoate underwent generation as well as dissipation during tea manufacturing. Sum of dimethoate and omethoate led to a large portion of 80.5-84.9% transferring into tea infusion. Results of safety evaluation indicated that omethoate could bring higher human health risk than dimethoate due to its higher hazard quotient by drinking tea. These results would provide information for the establishment of maximum residue limit and instruction for the application of dimethoate formulation on tea crop.

Determinations for Pesticides on Black, Green, Oolong, and White Teas by Gas Chromatography Triple-Quadrupole Mass Spectrometry

Black, green, white, and Oolong teas, all derived from leaves of Camellia sinensis, are widely consumed throughout the world and represent a significant part of the beverages consumed by Americans. A gas chromatography-triple quadrupole-based method, previously validated for pesticides on dried botanical dietary supplements, including green tea, was used to measure pesticides fortified into black and green teas at 10, 25, 100, and 500 μg/kg. Teas from 18 vendors of tea products were then surveyed for pesticides. Of 62 black, green, white, and Oolong tea products, 31 (50%) had residues of pesticides for which no United States Environmental Protection Agency tolerances are established for tea. The following pesticides were identified on tea leaves, with concentrations between 1 and 3200 μg/kg: anthraquinone, azoxystrobin, bifenthrin, buprofesin, chlorpyrifos, cyhalothrin, cypermethrin, DDE-p,p', DDT-o,p, DDT-p,p', deltamethrin, endosulfan, fenvalerate, heptachlor, hexachlorocyclohexanes (α,β,γ,δ), phenylphenol, pyridaben, tebuconazole, tebufenpyrad, and triazophos. DDT-p,p' was found at much higher concentrations than DDE-p,p' or DDT-o,p' in 9 of 10 teas with DDTs. A comparison between three commercially available solid-phase extraction (SPE) column brands of the same type revealed that two brands of SPE columns could be interchanged without modification of the tea method.

Enantioselective Dissipation of Acephate and Its Metabolite, Methamidophos, during Tea Cultivation, Manufacturing, and Infusion

The enantioselective dissipation of acephate and its metabolite, methamidophos, was investigated during tea cultivation, manufacturing, and infusion, using QuEChERS sample preparation technique and gas chromatography coupled with a BGB-176 chiral column. Results showed that (+)-acephate and (-)-acephate dissipated following first-order kinetics in fresh tea leaves with half-lives of 1.8 and 1.9 days, respectively. Acephate was degraded into a more toxic metabolite, methamidophos. Preferential dissipation and translocation of (+)-acephate may exist in tea shoots, and (-)-methamidophos was degraded more rapidly than (+)-methamidophos. During tea manufacturing, drying and spreading (or withering) played important roles in the dissipation of acephate enantiomers. The enantiometic fractions of acephate changed from 0.495-0.496 to 0.479-0.486 (P ≤ 0.0081), whereas those of methamidophos changed from 0.576-0.630 to 0.568-0.645 (P ≤ 0.0366 except for green tea manufacturing on day 1), from fresh tea leaves to made tea. In addition, high transfer rates (>80%) and significant enantioselectivity (P ≤ 0.0042) of both acephate and its metabolite occurred during tea brewing.