Dissipation kinetics and risk assessment of fluopyram and tebuconazole in mango (Mangifera indica)

The combination formulation of fluopyram and tebuconazole is used for control of fungal diseases and post-harvest disease management of mango. Dissipation study of the fungicides on mango was carried out after giving applications of fluopyram +tebuconazole at the standard and double doses of 150 + 150 and 300 + 300 g active ingredient hectare^?1 (g a.i. ha^?1), respectively. Fluopyram residues on mango were 0.8 and 0.9 mg kg^?1 and tebuconazole residues, 0.308 and 0.4 mg kg^?1 after three and four applications at the standard dose. At double dose treatment the residue levels for fluopyram were 1.266 and 1.453 mg kg^?1 and tebuconazole, 0.681 and 0.853 mg kg^?1, respectively. Residue dissipation in mango fruits followed first order rate kinetics and the half-life (DT₅₀) were 4.3–5.4 days for fluopyram and 3–3.8 days for tebuconazole. Faster dissipation of the fungicides was observed after the fourth treatment which directly correlated to higher rainfall during that period. The combined residues of fluopyram+tebuconazole reduced to below their maximum residue limits (MRLs) within 36–38 days. Dietary risk assessment on human health indicated that fluopyram and tebuconazole application to mango is unlikely to pose risk to human beings. This study gives valuable information on the judicious use of this combination formulation on mango, especially towards harvest.     

Simultaneous determination of boscalid and fludioxonil in grape and soil under field conditions by gas chromatography/tandem triple quadrupole mass spectrometry

A gas chromatography–tandem mass spectrometry method was developed and validated to simultaneously determine boscalid and fludioxonil in grape and soil samples. These samples were extracted with 10 mL of acetonitrile and purified using a mixed primary secondary amine/octadecylsilane sorbent. The method showed good linearity (R² > 0.99) in the calibration range 0.005–2 μg/mL for both pesticides. The limits of detection and quantification for the two analytes in grape and soil were 0.006 and 0.02 mg/kg, respectively. Fungicide recoveries in grape and soil were 81.18–92.11% for boscalid and 82.73–97.67% for fludioxonil with relative standard deviations of 1.31–10.31%. The established method was successfully applied to the residual analysis of boscalid and fludioxonil in real grape and soil samples. The terminal residue concentrations of boscalid and fludioxonil in grape samples collected from Anhui and Guizhou were <5 mg/kg (the maximum residue limit set by China) 7 days after the last application and 1 mg/kg (the maximum residue limit set by USA) 14 days after the last application. These results could provide guidance for the proper and safe use of boscalid and fludioxonil in grape and help the Chinese government to establish an MRL for fludioxonil in grape.     

Pesticide residue determination in vegetables from western China applying gas chromatography with mass spectrometry

In this study,an effort has been made to evaluate the pesticide residues in vegetables from western China. Fifty‐one pesticides, including organophosphorus, organochlorine, carbamate and pyrethroid, were detected in 369 commonly used vegetables by GC‐MS. Concentrations of organophosphorus pesticides were detected ranging from 0.0008 to 18.8200 mg/kg, among which organophosphorus pesticide concentrations exceeded their maximum residue levels (MRLs) in five samples. Carbamate and organochlorine pesticides were determined to have concentrations in the range of 0.0012–0.7928 mg/kg. The residual concentrations of carbamate pesticides in six samples and organochlorine pesticides in four samples exceeded their MRLs. The residual concentrations of five pyrethroid pesticides were within the range of 0.0016–6.0827 mg/kg and the pyrethroid residues in two samples exceeded their MRLs. The results revealed that pesticide residues in 70.73% of the vegetables samples were not detected, while in the rest of vegetables there were one or more pesticide residues and some even exceeded their MRLs, which would threaten the health of consumers. Our work provides significant information for the food safety regulations to control the excessive use of some pesticides on those kinds of vegetables from western China. Copyright © 2016 John Wiley & Sons, Ltd.     

Residue analysis and kinetics modeling of thiophanate-methyl,carbendazim, tebuconazole and pyraclostrobin in apple tree bark using QuEChERS/HPLC–VWD

Winter is the key period for the control of apple diseases, and fungicides are needed to protect the trunk or main branches. Fungicide residue in apple tree bark is an important basis for the action of the pesticide, but there are no reports on analytical methods or dissipation patterns. In this work, thiophanate-methyl, carbendazim, tebuconazole and pyraclostrobin were selected as typical fungicides and a new QuEChERS–HPLC–VWD(QuEChERS extraction followed by high-performance liquid chromatography detection with a variable wavelength detector) analytical method was developed to estimate their residue kinetics in apple tree bark during the winter months. In the pretreatment step, the sorbent for the clean-up of extracts was optimized as 60 mg/ml primary secondary amine and a gradient-elution model followed by a variable wavelength detection was developed for instrumental analysis. Then this method was validated and applied to the analysis of apple tree bark samples with the linearity range of 0.010–50.00 mg/L, quantification limit range of 0.028–0.080 mg/kg and recovery range of 86.1–101.4%. The dissipation kinetics of thiophanate-methyl and pyraclostrobin could be described by the first-order and two-phase kinetics models, respectively. For carbendazim and tebuconazole, two new models were developed to describe their residue kinetics.     

Analytical methods for pesticide residues in rice

Rice consumption has increased worldwide over recent decades, as it has become one of the most common foods. Although the analysis of environmental samples coming from rice areas has been well documented, there is less information regarding the analysis of pesticide residues in rice-grain samples.Rice (paddy, brown and white) can be considered a complex matrix, leading to difficulties in the application of the different multiresidue methods described in the literature. This review addresses and compares the principal extraction and clean-up methodologies [e.g., liquid-liquid extraction, solid-phase extraction, pressurized-liquid extraction, QuEChERS (quick, easy, cheap, effective, rugged and safe), gel-permeation chromatography and supercritical-fluid extraction - with QuEChERS-based methods being the most frequently employed].Traditionally, the determination of pesticide residues in rice has been based on gas chromatography with mass spectrometry (MS). But the application of new classes of pesticides has driven laboratories to increase the use of liquid chromatography with tandem MS. The limits of detection and quantification are in the ranges 0.09-90 μg/kg and 1-297 μg/kg, respectively, for the methodologies reported. These values agree with the current internationally-accepted maximum residue limits (MRLs).Based on the European Union (EU) database, more than 3000 analyses of pesticide residues in rice have been performed by official EU laboratories over the past decade. Of these, 6% reported pesticide residues above the MRLs.Physico-chemical properties can explain the occurrence of pesticides in rice commodities: lipophilic pesticides are frequently found in brown rice, whereas fungicides are mainly found in milled rice. Carbendazim, malathion, iprodione, tebuconazole, quinclorac and tricyclazole are the pesticides most frequently found in white rice, while buprofezin, hexaconazole, chlorpyrifos and edifenphos are most commonly found in paddy rice.Pesticide-residue concentrations can be affected during rice processing - with concentrations generally lower in the final products. However, few studies focusing on primary processing have addressed the setting of precise values applicable for the processing factors.     

Detection and Risk Assessments of Multi-Pesticides in Traditional Chinese Medicine Chuanxiong Rhizoma by LC/MS-MS and GC/MS-MS

With the internationalization of traditional Chinese medicines (TCMs) and the increasing use of herbal medicines around the world, there are concerns over their safety. In recent years, there have been some sporadic reports of pesticide residues in Chuanxiong Rhizoma (CX), although the lack of systematic and comprehensive analyses of pesticide residues and evaluations of toxicological risks in human health has increased the uncertainty of the potential effects of pesticides exposure in humans. This study aimed to clarify the status of pesticide residues and to determine the health risks of pesticide residues in CX. The findings of this study revealed that 99 batches of CX samples contained pesticide residues ranging from 0.05 to 3013.17 μg/kg. Here, 6–22 kinds of pesticides were detected in each sample. Prometryn, carbendazim, dimethomorph, chlorpyrifos, chlorantraniliprole, pyraclostrobin, and paclobutrazol were the most frequently detected pesticides, with detection rates of 68.69–100%. Insecticides and fungicides accounted for 43.23% and 37.84% of the total pesticides detected, respectively. Here, 86.87% of the pesticide content levels were lower than 50 μg/kg, and a small number of samples contained carbofuran, dimethoate, and isofenphos-methyl exceeding the maximum residue levels (MRLs). A risk assessment based on the hazard quotient/hazard index (HQ/HI) approach revealed that the short-term, long-term, and cumulative risks of pesticide residues in CX are well below the levels that may pose a health risk. Worryingly, six banned pesticides (carbofuran, phorate sulfone, phorate-sulfoxide, isofenphos-methyl, terbufos-sulfone, and terbufoxon sulfoxide) were detected. This study has improved our understanding of the potential exposure risk of pesticide multi-residues in CX. The results of the study will have a positive impact on improving the quality and safety of CX and the development of MRLs for pesticide residues.     

Multiresidue determination of 11 new fungicides in grapes and wines by liquid–liquid extraction/clean-up and programmable temperature vaporization injection with analyte protectants/gas chromatography/ion trap mass spectrometry

A gas chromatographic ion trap mass spectrometry (GC-ITMS) method was developed for the determination of 11 new generation fungicides (benalaxyl, benalaxyl-M, boscalid, cyazofamid, famoxadone, fenamidone, fluquinconazole, iprovalicarb, pyraclostrobin, trifloxystrobin and zoxamide) in grapes and wines. Samples were extracted with ethyl acetate:hexane (1:1, v/v) and cleaned-up with graphitized carbon black/primary secondary amine (GCB/PSA) solid-phase extraction (SPE) cartridges using acetonitrile:toluene (3:1, v/v) as eluent. The addition of analyte protectants (3-ethoxy-1,2-propanediol, d-sorbitol and l-gulonic acid γ-lactone) in the final extracts allowed to avoid the matrix-induced response enhancement effect on quantitation process with absolute recoveries ca. 100%. Precision (expressed as relative standard deviation) was lower than 16% for all fungicides. Limits of detection and quantitation were lower than 0.01 mg/kg or mg/L, except for cyazofamid, much smaller in all cases than maximum residue levels (MRLs) established by European Union for grapes and by Switzerland and Italy for wines. The proposed method was applied to determine fungicide residues in three different white grapes for vinification produced in Ribeiro area in Galicia (NW Spain), as well as in their corresponding final wines.     

Evaluation of different sample treatments for determining pesticide residues in fat vegetable matrices like avocado by low-pressure gas chromatography-tandem mass spectrometry

A multi-residue method has been developed for determining 65 pesticide residues in greasy vegetable matrices such as avocado. Conventional organic solvent extraction assisted by a high-speed homogenizer was compared to pressurized liquid extraction (PLE) as extraction techniques. Following this, the lipophilic extract was purified using gel permeation chromatography (GPC). Alternative clean-up methods were also evaluated, as solid-phase extraction cartridges individually used and downstream coupled, but less effective lipophilic separation was archived. The pesticide residue determination was carried out using low-pressure gas chromatography coupled to tandem mass spectrometry (LP-GC-MS-MS), showing the applicability of this type of GC columns for the analysis of fat vegetable matrices. The proposed methodology was validated in avocado matrix. The recoveries were in the range 70-110%, with RSD values lower than 19%, at 12 and 50 microg/kg spiking levels. The limits of quantitation (LOQs) were in the range 0.04-8.33 microg/kg and the limits of detection (LODs) were between 0.01 and 2.50 microg/kg. All of them were lower than the maximum residue levels (MRLs) set by the European Union (EU) in avocado. The proposed method was evaluated analyzing pesticide residues in real avocado samples.     

桃中农药残留分析及膳食暴露评估研究

为明确并量化食用桃途径的农药膳食摄入风险水平,通过对19个桃主产区采集的98份样品进行农药残留检测,对桃中的农药残留急/慢性膳食摄入风险进行评估,并借鉴英国兽药残留委员会兽药残留风险排序矩阵进行农药和样品风险排序。结果在桃中检出了38种农药残留,98个样品的检出率为95.9%,检出的农药含量为0.007 4～3.399 3 mg/kg;检出农药的慢性膳食摄入风险(%ADI)和急性膳食摄入风险(%ARfD)的平均值分别为0.89%和11.09%,风险均低于100%,不会对人体产生慢性或急性风险;风险排序结果表明桃果品中氟虫腈、硫丹、灭多威、丁硫克百威、毒死蜱、联苯菊酯为6种为高风险农药,应在生产和质量安全监管中予以重点关注。该文为桃安全消费、农药残留监管和农药最大残留限量(MRLs)制修订提供了科学依据。     

Simultaneous determination of tebuconazole,trifloxystrobin, and its metabolite trifloxystrobin acid residues in gherkin under field conditions

A rapid, simple, and selective analytical method for the simultaneous determination of tebuconazole, trifloxystrobin, and its metabolite trifloxystrobin acid residues in gherkin and soil was developed and validated by gas chromatography coupled with mass spectrometry. The samples were extracted with acetonitrile and cleaned up by dispersive solid‐phase extraction with primary secondary amine sorbent. The limit of quantification of the method was 0.05 mg/kg for all three compounds. The method was validated using blank samples spiked at three levels and recoveries ranged from 83.5 to 103.8% with a relative standard deviation of 1.2 to 4.8%. The developed method was validated and applied for the analysis of a degradation study sample. The residues of trifloxystrobin and tebuconazole were found to dissipate following first‐order kinetics with half‐life ranging between 3.31–3.38 and 3.0–3.04 days, respectively, for two different dosages. Pesticide residues were below the European Union maximum residue level after seven days for trifloxystrobin (0.2 mg/kg) and ten days for tebuconazole (0.05 mg/kg), which suggested the use of this fungicide mixture to be safe to humans. These results can be utilized in formulating the spray schedule and safety evaluation on trifloxystrobin and tebuconazole in gherkin crop.     

Degradation of parathion methyl on field-sprayed apples and stored apples

Residue levels of parathion methyl on field-sprayed Granny-Smith apples were studied. The pesticide was applied according to producer recommendations. Apples received a single spraying at a rate of 40 g active ingredient/100 L. Residues were determined with a simple gas chromatographic method. Recovery of parathion methyl was 88-108%, and the limit of determination was 0.002 mg/kg. Decomposition of parathion methyl was studied in apples remaining on trees after spraying and in apples harvested and stored under ambient-temperature, refrigerated-room, and controlled-atmosphere conditions. During post harvest storage, parathion methyl degrades more slowly than on apples remaining on the trees. Best-fit curves were determined, and kinetic equations, rate constants, and half-lives were calculated. Half-lives found were 8 days for apples on trees, 45 days for apples stored at ambient conditions, 68 days for apples stored in controlled-atmosphere room, and 62 days for apples stored in a refrigerated room. Under storage conditions, levels of parathion methyl residues need a long time to become lower than the legal limit (0.2 mg/kg).     

Determination of five pesticide residues in oranges by matrix solid-phase dispersion and liquid chromatography to estimate daily intake of consumers.

Residues of benzoylphenylurea insecticides (diflubenzuron, hexaflumuron, and flufenuxuron), carboxamide acaricides (hexythiazox), and carbamate insecticides (benfuracarb) were determined in 150 orange fruit samples from September 1998 to June 1999, to estimate exposure of the Valencian population to oranges contaminated with these newly developed pesticides. The method for monitoring these residues is based on matrix solid-phase dispersion and liquid chromatography with UV or atmospheric pressure chemical ionization/mass spectrometry (APCI/MS) detection. Orange samples representing 11 varieties were collected from an agricultural cooperative and examined for the 5 pesticides. In 74.6% of all analyzed samples, the pesticide residues were below detection limits, which ranged from 0.002 to 0.05 mg/kg. Residues were detected in 25.4% of the samples, with higher incidences of diflubenzuron, flufenuxuron, hexythiazox, and benfuracarb; hexaflumuron residues were detected only occasionally. Two different pesticides exceeded maximum residue limits (MRLs) in 4 (2.7%) of the orange samples. Diflubenzuron surpassed 1 mg/kg MRL in 3 samples and flufenuxuron exceeded the 0.3 mg/kg MRL in 3 samples. The estimated daily intake of the 5 pesticide residues during the period was 0.077 microg/kg body weight per day. This value is much lower than the total admissible daily intake proposed by the Food and Agricultural Organization and the World Health Organization.     

Evaluation of Dissipation Behavior,Residues, and Dietary Risk Assessment of Fludioxonil in Cherry via QuEChERS Using HPLC-MS/MS Technique

The chemical fungicide fludioxonil is widely used to control post-harvest fungal disease in cherries. This study was implemented to investigate the dissipation behaviours and residues of fludioxonil on cherries. A reliable and efficient analytical method was established. Cherry samples from four product areas were analyzed by QuEChERS and HPLC-MS/MS methods with acceptable linearity (R² > 0.99), accuracy (recoveries of 81–94%), and precision (relative standard deviation of 2.5–11.9%). The limits of quantification (LOQs) and limits of detection (LODs) of cherries were 0.01 mg/kg and 0.005 mg/kg. The dissipation of fludioxonil on cherries followed first order kinetics with half-lives of 33.7–44.7 days. The terminal residues of fludioxonil were all lower than 5.00 mg/kg, which is the MRL recommended by the European Commission. According to Chinese dietary patterns and terminal residue distributions, the risk quotient (RQs) of fludioxonil was 0.61%, revealing that the evaluated cherries exhibited an acceptably low dietary risk to consumers.     

Determination of fungicide residues in white grapes for winemaking by gas chromatography with mass spectrometric detection and assessment of matrix effects

A new analytical method, based on organic solvent extraction with dichloromethane-acetone (75 + 25, v/v) followed by gas chromatography with mass spectrometric detection, is presented for the determination of residues of 10 fungicides in white grapes for vinification. Some of them (cyprodinil, fludioxonil, and pyrimethanil) have been used for only 2-3 years and, therefore, no methods are available in the scientific literature for such a screening. Quality parameters yielded good precision (relative standard deviation of <10%) and detection limits (ranging between 1 and 18 microg/kg) that are lower than the maximum residue limits (MRLs) set by the 76/895/European Economic Community (EEC) and 90/642/EEC Directives. The applicability of the method was evaluated by analysis of 5 different white grapes produced in the Rías Baixas area in Galicia (northwestern Spain) for vinification. The method showed good performance in analyses of real samples to determine whether the concentrations of the fungicides used exceeded their MRLs. The method of standard additions was found to be necessary to avoid matrix effects in the quantification of fungicide residues. Results showed that concentrations of the fungicides identified in grapes were lower than the MRLs established by the European legislation.     

Simultaneous determination and method validation of difenoconazole,propiconazole and pyraclostrobin in pepper and soil by LC–MS/MS in field trial samples from three provinces,China

A liquid chromatography–electrospray ionization tandem mass spectrometry method was developed for simple and accurate detection of the fungicides difenoconazole, propiconazole and pyraclostrobin in peppers and soil. Three fungicides residues were extracted from samples by acetonitrile and cleaned up by dispersive solid‐phase extraction before instrumental analysis. The accuracy and precision of the method were evaluated by conducting an intra‐ and inter‐day recovery experiment. The limits of quantification and detection of difenoconazole, propiconazole and pyraclostrobin in pepper and soil were 0.005 and 0.0015 mg/kg, respectively. The recoveries were investigated by spiking pepper and soil at three levels, and were found to be in the ranges 79.62–103.15% for difenoconazole, 85.94–103.35% for propiconazole and 80.14–97.69% for pyraclostrobin, with relative standard deviations <6.5%. Field experiments were conducted in three locations in China. The half‐lives of difenoconazole, propiconazole and pyraclostrobin were 5.3–11.5 days in peppers and 6.1–32.5 days in soil. At harvest, pepper samples were found to contain difenoconazole, propiconazole and pyraclostrobin well below the maximum residue limits of European Union at the interval of 21 days after last application following the recommended dosage.     

改进的QuEChERS方法结合液相色谱-四极杆-飞行时间质谱快速筛查与确证调味茶中52种农药残留

建立了调味茶中52种农药残留的QuEChERS方法结合液相色谱-四极杆-飞行时间质谱（LC-Q-TOF-MS）快速筛查方法。采用乙腈提取样品，经N-丙基乙二胺（PSA）、石墨化炭黑（GCB）、C₁₈净化，LC-Q-TOF-MS测定。结果表明：52种农药在调味茶中4个添加水平（10、20、50和100 μg/kg）下的回收率均在70%~120%之间，相对标准偏差（RSD，n=3）均小于20%，52种农药线性良好，线性相关系数（r）均大于0.99。52种添加农药的筛查限为0.001~0.01 mg/kg，定量限为0.002~0.02 mg/kg，均低于添加农药的欧盟最大残留限量（MRL）标准。该方法样品前处理简单、分析时间短、灵敏、可靠，适用于茶叶中多种农药残留的检测。     

Dissipation and residue behaviour of oryzalin in grape ecosystem using RRLC-QqQ-MS/MS

The dissipation and terminal residues of oryzalin in grape ecosystem under open-field condition were investigated at two different locations, Beijing and Shandong in China. Residues in field-treated samples were determined by a sample method using rapid resolution liquid chromatography triples quadrupole tandem mass spectrometry (RRLC-QqQ-MS/MS). This method showed satisfactory qualitative and quantitative performance. The mean recoveries of oryzalin at different fortification levels (0.01, 0.1 and 1 mg/kg for grape; 0.01, 0.1, 1, 10 and 30 mg/kg for soil) ranged from 88.2% to 98.8%, with the relative standard deviations ≤4.9%. The limits of detection and quantification were, respectively, 0.003 and 0.01 mg/kg. In soil, the dissipation half-lives were about 9 days and the terminal residues ranged from <0.01 to 0.58 mg/kg in both Beijing and Shandong. The concentrations of oryzalin in grapes were lower than 0.01 mg/kg in most of the samples of dissipation study and all the samples of residue study. As far as we know, this is the first study focusing on the dissipation and terminal residue of oryzalin in grape ecosystem, and no maximum residue limits (MRLs) of oryzalin in grapes were recommended by China, Codex Alimentarius Commission or European Union . Therefore, these data not only provide important information about the fate and residues of oryzalin in grape ecosystem, but also could be very useful for the establishment of the MRLs of oryzalin in grapes.     

QuEChERS-UPLC-MS/MS法检测苹果中5种农药残留

建立了QuEChERS-超高效液相色谱-串联质谱(QuEChERS-UPLC-MS/MS)检测苹果中5种农药残留的分析方法.样品采用QuEChERS进行前处理,乙腈提取,经PSA、纳米氧化锆(Nano-ZrO2)和多壁碳纳米管(MWCNTs)组合净化,结合UPLC-MS/MS检测,外标法定量.结果表明,在0.005～0...     

Multi-residue screening of pesticides in vegetables,fruits and baby food by stir bar sorptive extraction-thermal desorption-capillary gas chromatography-mass spectrometry

The performance of stir bar sorptive extraction (SBSE) for the enrichment of pesticides from vegetables, fruits and baby food samples is discussed. After extraction with methanol, an aliquot is diluted with water and SBSE is performed for 60 min. By applying a new thermal desorption unit (TDU), fully automated and unattended desorption of 98 stir bars is feasible, making SBSE very cost-effective. The presence of pesticide residues is elucidated with the retention time locked gas chromatography–mass spectroscopy method (RTL-capillary GC–MS). With SBSE–RTL-capillary GC–MS operated in the scan mode, more than 300 pesticides can be monitored in vegetables, fruits and baby food. The multi-residue method (MRM) described provides detectabilities from the mg/kg (ppm) to the sub-μg/kg (ppb) level, thereby complying with the maximum residue levels (MRLs) set by regulatory organizations for pesticides in different matrices. Several examples, i.e. pesticide residues in lettuce, pears, grapes and baby food, illustrate the potential of SBSE–RTL-capillary GC–MS.     

Study on pesticide residues in apples,apple-based baby food,and their behaviour during processing using fast GC–MS multiresidue analysis

Food-processing experiments using apples were conducted to obtain more knowledge on the behaviour of pesticides during apple-based baby-food production. The residues were determined in raw material (apples), in intermediate products at different steps of the processing procedure (baby food production) and in final products (apple purée) using a rapid GC–MS method in combination with two different sample-preparation approaches. During 2 years of a monitoring programme, 84 analyses of apple samples and 102 of baby food sample apple purée intermediate and final product samples from baby food production were performed. A pesticide-residue search revealed that residues in fresh apples do not exceed the maximum residue limit for the adult population, but there were some positive findings concerning apples as baby food. The maximal pesticide concentration (fluquinconazole) found in apples was 0.099?mg?kg^?1. In the processed apple-based baby food the concentration of pesticide residues were mostly below 0.010?mg?kg^?1.