Simultaneous determination of difenoconazole,trifloxystrobin and its metabolite trifloxystrobin acid residues in watermelon under field conditions by GC–MS/MS

An optimized quick, easy, cheap, effective, rugged and safe method for the simultaneous determination of difenoconazole, trifloxystrobin and its metabolite trifloxystrobin acid residues in watermelon and soil was developed and validated by gas chromatography with tandem mass spectrometry. The samples were extracted with acetonitrile (1% formic acid) and cleaned up by dispersive solid‐phase extraction with octadecylsilane sorbent. The limit of quantification of the method was 0.01 mg/kg, and the limit of detection was 0.003 mg/kg for all three analytes. The recoveries of the fungicides in watermelon, pulp and soil were 72.32–99.20% for difenoconazole, 74.68–87.72% for trifloxystrobin and 78.59–92.66% for trifloxystrobin acid with relative standard deviations of 1.34–14.04%. The dissipation dynamics of difenoconazole and trifloxystrobin in watermelon and soil followed the first‐order kinetics with half‐lives of 3.2–8.8 days in both locations. The final residue levels of difenoconazole and trifloxystrobin were below 0.1 mg/kg (maximum residue level [MRL] set by China) and 0.2 mg/kg (MRL set by European Union), respectively, in pulp samples collected 14 days after the last application. These results could help Chinese authorities to establish MRL of trifloxystrobin in watermelon and provide guidance for the safe and proper application of both fungicides on watermelon.     

Determination,residue and risk assessment of trifloxystrobin,trifloxystrobin acid and tebuconazole in Chinese rice consumption

A simple and rapid analytical method for the detection of trifloxystrobin, trifloxystrobin acid and tebuconazole in soil, brown rice, paddy plants and rice hulls was established and validated by liquid chromatography with tandem mass spectrometry. Acceptable linearity (R² > 0.99), accuracy (average recoveries of 74.3–108.5%) and precision (intra- and inter-day relative standard deviations of 0.9–8.8%) were obtained using the developed determination approach. In the field trial, the half-lives of trifloxystrobin and tebuconazole in paddy plants were 5.7–8.3 days in three locations throughout China, and the terminal residue concentrations of trifloxystrobin and tebuconazole were <100 and 500 μg/kg (maximum residue limits set by China), respectively, at harvest, which indicated that, based on the recommended application procedure, trifloxystrobin and tebuconazole are safe for use on rice. The risk assessment results demonstrated that, owing to risk quotient values of both fungicides being <100%, the potential risk of trifloxystrobin and tebuconazole on rice was acceptable for Chinese consumers. These data could provide supporting information for the proper use and safety evaluation of trifloxystrobin and tebuconazole in rice.     

Simultaneous determination of trifloxystrobin and trifloxystrobin acid residue in rice and soil by a modified quick,easy, cheap,effective, rugged,and safe method using ultra high performance liquid chromatography with tandem mass spectrometry

A sensitive analytical method for the simultaneous determination of trifloxystrobin and its metabolite trifloxystrobin acid in rice including straw, bran, brown rice and soil was developed by using ultra high performance liquid chromatography coupled with tandem mass spectrometry. The fungicide trifloxystrobin and its metabolite trifloxystrobin acid were extracted using acetonitrile with 1% formic acid v/v and subsequently cleaned up by primary secondary amine, octadecylsilane or graphitized carbon black prior to ultra high performance liquid chromatography coupled with tandem mass spectrometry. The determination of two target compounds was achieved in less than 3 min using an electrospray ionization source in positive mode. The limits of detection were below 0.22 μg/kg and the limits of quantification did not exceed 0.74 μg/kg in all matrices, which were much lower than the maximum residue levels established by the Codex Alimentarius Commission. The overall average recoveries in four matrix at three levels (0.1, 1.0 and 5.0 mg/kg) ranged from 74.2 to 107.4% with a relative standard deviations of less than 7.8% (n = 5) for both analytes. The method was demonstrated to be convenient and reliable for the routine monitoring of trifloxystrobin and its metabolite. The developed method was validated and applied for the analysis of degradation study samples.     

Persistence of trifloxystrobin and tebuconazole in banana tissues and soil under the semi-arid climatic conditions of Karnataka,India

Trifloxystrobin and tebuconazole are used for control of Sigatoka leaf spot disease of banana. This study was conducted to evaluate residue persistence of the fungicides in/on banana fruit, other edible parts and soil after spray application of the combination formulation, Nativo 75 WG, at the standard dose, 87.5 + 175 and double dose, 175 + 350 g a.i. ha^?1. The fungicides were extracted from banana and soil with acetone, partitioned into dichloromethane and cleaned-up using activated charcoal for trifloxystrobin and primary/secondary amine (PSA) for tebuconazole samples. The limit of quantification of the method was 0.05 mg kg^?1 for both fungicides. Initial residues of trifloxystrobin were 0.444 and 0.552 mg kg^?1 in/on banana with peel (whole fruit), which reached <0.05 and 0.065 mg kg^?1 after 30 days from treatment at the standard and double doses, respectively. Tebuconazole residues were 0.636 and 960 mg kg^?1 initially and reduced to 0.066 and 0.101 mg kg^?1 after 30 days. Trifloxystrobin and tebuconazole degraded with the half-life of about 11 days. Trifloxystrobin or its metabolite was not detected in the fruit pulp. Tebuconazole being systemic in nature moved to the fruit pulp which was highest on the 3rd day (0.103 and 0.147 mg kg^?1) and remained for 15 days. Matured banana fruit, flower, pseudostem and field soil were free from fungicide residues. For consumption of raw banana 43 days pre-harvest interval (PHI) is required after treatment of the combination formulation. Therefore application of the fungicides towards maturity stage of the fruits may be avoided.     

Rapid gas chromatographic method for the determination of famoxadone, trifloxystrobin and fenhexamid residues in tomato, grape and wine samples

Trifloxystrobin, fenhexamid and famoxadone belong to the generation of fungicides acting against a broad spectrum of fungi and widely used in Integrated Pest Management strategies in different agricultural crops but mainly in viticulture. In the present work, a gas chromatographic (GC) method for their determination was developed and validated on tomato, grape and wine matrices. The method was based on a simple one step liquid-liquid microextraction with cyclohexane/dichloromethane (9+1, v/v) and determination of fungicides by gas chromatography with nitrogen phosphorous (NP-) and electron capture (EC-) detection, and ion trap mass spectrometry (ITMS) for confirmation. The method was validated by recovery experiments, assessment of matrix effect and calculation of the associated uncertainty. Recoveries for GC-NPD and GC-ECD were found in the range of 81-102% with RSD <12%, while matrix-matched calibration solutions were imposed for quantification. LOQs ranged from 0.005 to 0.05 mg/kg and 0.01 to 0.10 mg/kg for the GC-ECD and GC-NPD, respectively, depending on the sensitivity of each compound with trifloxystrobin being the most sensitive. The expanded uncertainty, calculated for a sample concentration of 0.10 mg/kg, ranged from 4.8 to 13% for the GC-ECD and from 5.4 to 29% for the GC-NPD. The concentration levels for famoxadone residues found in tomato and grape samples from field experiments were clearly below the EU established MRL values, thus causing no problems in terms of food safety.     

Determination of tebuconazole, trifloxystrobin and its metabolite in fruit and vegetables by a Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method using gas chromatography with a nitrogen-phosphorus detector and ion trap mass spectrometry

A new analytical method using QuEChERS procedure by gas chromatography with a nitrogen-phosphorus detector (GC-NPD) and ion trap mass spectrometry (GC-IT-MS) for the quantitative determination of tebuconazole, trifloxystrobin and its metabolite trifloxystrobin acid has been developed and validated. The analytes were extracted from five fruit and vegetable matrices using acetonitrile and subsequently cleaned up using primary secondary amine (PSA) or octadecylsilane (C18) as sorbent prior to GC analysis. The present methods provided sufficient sensitivity as reflected by the values of limit of detection (LOD) and limit of quantification (LOQ) of 0.4-7 and 1.2-20 μg/kg for GC-IT-MS/MS and GC-NPD. The recoveries were, on average, 68-117 and 68-121%, respectively, for three compounds by GC-NPD and GC-IT-MS/MS with intra-day precision achieved with an RSD of 2.7-19.1%. The inter-day precision was better than 15.1% as determined by GC-NPD. The QuEChERS procedure, by using two sorbents (PSA and C18) and the matrix-matched standards, gave satisfactory recoveries and RSD values in different matrices. IT-MS acquisition provided higher specificity and selectivity for pesticides and better limit of detection and quantification. However, the repeatability and precision of NPD method were better compared with IT-MS.     

Dissipation,residues and risk assessment of spirotetramat and its four metabolites in citrus and soil under field conditions by LC‐MS/MS

A modified Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method for the simultaneous determination of spirotetramat and its four metabolite residues in citrus, peel, pulp and soil was developed and validated by liquid chromatography with tandem mass spectrometry (LC‐MS/MS). The samples were extracted with acetonitrile (1%, glacial acetic acid, v/v) and purified using primary secondary amine and octadecylsilane. The limit of detection was 0.01–0.13 mg/kg, whereas that of quantification was 0.02–0.40 mg/kg for spirotetramat and its metabolites. The average recoveries of spirotetramat, spirotetramat‐enol, spirotetramat‐mono‐hydroxy, spirotetramat‐enol‐glucoside and spirotetramat‐ketohydroxy in all matrices were 73.33–107.91%, 75.93–114.85%, 76.44–100.78%, 71.46–103.19% and 73.08–105.27%, respectively, with relative standard deviations < 12.32%. The dissipation dynamics of spirotetramat in citrus and soil followed first‐order kinetics, with half‐lives of 2.3–8.5 days in the three sampling locations. The terminal residues of spirotetramat in four matrices at the three locations were measured below the 1.0 mg/kg maximum residue limit set by China, and residues were found to be concentrated on the peel. The risk assessment of citrus was evaluated using risk quotients. The risk quotient values were found to be significantly <1, suggesting that the risk to human health was negligible when using the recommended doses of spirotetramat in citrus. These results could provide guidance for the safe and proper application of spirotetramat in citrus in China.     

Method validation,residue analysis and dietary risk assessment of trifloxystrobin and trifloxystrobin acid in milk,eggs and pork

Trifloxystrobin (TFS) is a widely used strobilurin fungicide and its residues accumulating in animal-derived food could result in potential harm to consumers. By optimization of extraction solvents and cleanup sorbents, a residue analysis method for TFS and its metabolite trifloxystrobin acid (TFSA) was established in milk, eggs and pork based on QuEChERS sample preparation and LC–MS/MS. The calibration curves exhibited good linearity with determination coefficients (R²) >0.9930 over the range of 0.5–250 ng/ml for both TFS and TFSA. The recoveries of the two analytes were 81–100% with RSD 3–10% and 76–96% with RSD 2–13%, respectively. The limit of quantification (LOQ) was 1 ng/g for both analytes. The milk, egg and pork samples, 30 each, were collected from the 30 main producing regions in China, and residues of TFS and TFSA were analyzed. The concentrations of both analytes were lower than the corresponding LOQs and maximum residue limits. Long-term dietary risk assessment showed that the hazard quotients were 0.001–0.003%, indicating an absence of unacceptable risks in milk, eggs and pork to the health of common consumers in China.     

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.     

Residue analysis of kresoxim‐methyl and boscalid in fruits,vegetables and soil using liquid–liquid extraction and gas chromatography–mass spectrometry

A GC‐MS procedure for simultaneously determining and validating kresoxim‐methyl and boscalid has been developed in fruit, vegetable and soil matrices. The method was based on one‐step liquid–liquid extraction with acetone and dichloromethane solvents. Estimated limits of detection (LODs) for kresoxim‐methyl and boscalid were 0.006 and 0.015 mg/kg, and limits of quantification (LOQs) were 0.02 and 0.05 mg/kg, respectively. The intra‐ and inter‐ precision were achieved with RSD better than 13.8 and 14.5%, and recoveries were in the range of 77.1–98.7% for kresoxim‐methyl and 72.8–105.1% for boscalid. The expanded uncertainties calculated at 0.1 mg/kg were below 18%. Concentration levels for residues of the two fungicides in melon samples from field trials collected 7 days after the last application were clearly below the established MRL values. Copyright © 2009 John Wiley & Sons, Ltd.     

Application of liquid chromatography with electrospray tandem mass spectrometry to the determination of a new generation of pesticides in processed fruits and vegetables

This paper describes a method for the sensitive and selective determination of 24 new pesticide residues (azoxystrobin, trifloxystrobin, kresoxim-methyl, fenazaquin, indoxacarb, fenothiocarb, furathiocarb, benfuracarb, imidachloprid, dimethomorph, fenpyroximate, hexythiazox, tebufenpyrad, tebufenozide, difeconazole, fenbuconazole, flusilazole, paclobutrazol, tebuconazole, tetraconazole, bromuconazole, etofenprox, fenhexamid, pyridaben) in apple puree, concentrated lemon juice and tomato puree. A miniaturized extraction-partition procedure requiring small amounts of non-chlorinated solvents was used. The extracts are analyzed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS) without any further clean-up step. The pesticides are separated on a reversed-phase polar column using a gradient elution. Fifty-five simultaneous MS-MS transitions of precursor ions were monitored (two or three for each pesticide). Studies at fortification levels of 0.001-0.020 and 0.010-0.200 mg/kg gave mean recoveries ranging from 76 to 106% for all compounds, except for imidacloprid, with (R.S.D.s) < or = 15%. The excellent sensitivity and selectivity of LC-MS-MS method allowed quantitation and identification at low levels also in difficult matrices with a run time of 20 min. With the developed method almost 100 samples of commercial fruit products (nectars, juices, purees) were analyzed. None of samples contained residues higher than 0.010 mg/kg.     

气相色谱/质谱法测定食品中甲氧基丙烯酸酯类杀菌剂残留

建立了一种专属、灵敏的气相色谱-质谱分析方法,用于检测水果、蔬菜、饮料、粮谷类、坚果类和肉、蛋、奶类等多种类型食品中嘧菌酯、醚菌胺、嘧蟎酯、氟嘧菌酯、醚菌酯、Z-苯氧菌胺、E-苯氧菌胺、肟醚菌胺、啶氧菌酯、唑菌胺酯和肟菌酯等11种甲氧基丙烯酸酯类杀菌剂残留量。对于不同类型的样品,使用不同有机溶剂对甲氧基丙烯酸酯类杀菌剂进行超声波提取,经凝胶渗透色谱对样品提取液进行净化、富集,采用气相色谱-质谱法以选择离子监测模式进行定性,外标法定量。上述各种杀菌剂在0.05~5.0 mg/kg浓度范围内呈线性,相关系数r>0.99。在空白样品中,添加甲氧基丙烯酸酯类杀菌剂的回收率在60.3%~120.0%之间,精密度(RSD)为1.54%~13.41%。各组分检出限均在0.002~0.015 mg/kg之间。     

Residues of four triazole fungicides in tobacco leaves under field condition and during curing

Residues of four triazole fungicides (triadimefon, myclobutanil, tebuconazole and difenoconazole) in tobacco leaves under field condition and during curing were investigated. Following extraction with acetonitrile, the samples were cleaned up by a Florisil solid phase extraction column, and then determined by gas chromatography–mass spectrometry in selected ion monitoring mode. The average recoveries of the four triazole fungicides were found in the range of 82.7–97.3% with relative standard deviations of 1.1–4.6% in green and cured tobacco leaves. The residues of triadimefon, myclobutanil, tebuconazole and difenoconazole in Shandong, Sichuan, Yunnan, Liaoning and Jiangxi were found in the range of 0.02–0.32 mg/kg, 0.41–4.93 mg/kg, 0.37–9.84 mg/kg and 0.25–4.85 mg/kg in cured tobacco leaves when measured 14 days after the last application. The residue levels of the four triazole fungicides in most cured tobacco samples were lower than that in green tobacco samples, indicating that high temperature degradation surpassed dehydration concentration during the curing process.     

Pharmacokinetics,bioavailability and metabolism of scopoletin in dog by ultra‐high‐performance liquid chromatography combined with linear ion trap–Orbitrap tandem mass spectrometry

A highly sensitive and selective method based on ultra‐high‐performance liquid chromatography combined with linear ion trap–Orbitrap tandem mass spectrometry (UHPLC–LTQ–Orbitrap–MS) has been developed and validated for the determination of scopoletin in dog plasma. The analyte was extracted from plasma samples using acetonitrile and separated on an Acquity UPLC BEH C₁₈ column (50 × 2.1 mm, 1.7 μm) with 0.05% ammonium hydroxide and acetonitrile as mobile phase. The developed method was linear over the concentration range of 1–500 ng/mL, with a correlation coefficient >0.9988. The intra‐ and inter‐day precisions (RSD) were <8.93% while the accuracy (RE) ranged from ?6.50 to 8.12%. Extraction recovery, matrix effect and stability for dog plasma samples were within the required limits. The validated method has been successfully applied to investigate the pharmacokinetics and metabolism of scopoletin in dog plasma after intravenous (1 mg/kg) and oral (10, 25, 50 mg/kg) administration. The results revealed that (a) scopoletin showed short elimination half‐life in dog; (b) its oral bioavailability was low (within the range of 5.69–7.08%); (c) scopoletin showed dose‐independent pharmacokinetic profiles in dog plasma over the dose range of 10–50 mg/kg; and (d) glucuronidation was the predominant metabolic pathway in dog.     

Simultaneous determination of residues of metalaxyl,cyazofamid and a cyazofamid metabolite in tobacco leaves and soil by liquid chromatography with tandem mass spectrometry

A simple method was developed and validated for the simultaneous determination of metalaxyl, cyazofamid and the cyazofamid metabolite 4‐chloro‐5‐p‐tolylimidazole‐2‐carbonitrile (CCIM) by liquid chromatography with tandem mass spectrometry. The three target compounds were extracted from tobacco and soil with acetonitrile containing 0.1% acetic acid, and the extracts were purified using octadecylsilane. The proposed method showed satisfactory linearity (R² ≥ 0.9985) for the target compounds. The limits of detection for metalaxyl, cyazofamid and CCIM were 0.006, 0.06 and 0.06 mg/kg in soil and green tobacco leaves and 0.03, 0.3 and 0.3 mg/kg in cured tobacco leaves, respectively. The limits of quantification for metalaxyl, cyazofamid and CCIM were 0.02, 0.2 and 0.2 mg/kg in soil and green tobacco leaves and 0.1, 1 and 1 mg/kg in cured tobacco leaves, respectively. The average recoveries from soil and tobacco were 72.91–98.40% for metalaxyl, 76.73–105.80% for cyazofamid and 74.48–106.45% for CCIM. The relative standard deviation range was 1.23–6.99%. The developed method was successfully applied to analysis of residues of metalaxyl, cyazofamid and CCIM in real soil and tobacco samples. The results indicated that the established method could meet the requirement for the analysis of trace amounts of all three analytes in soil and tobacco.     

Monitoring residue levels and dietary risk assessment of pymetrozine for Chinese consumption of cauliflower

The present study investigates the occurrence of pymetrozine residues in cauliflower samples obtained from six cauliflower‐producing areas of China during fixed time periods in 2017 and estimates the dietary risk of pymetrozine in cauliflower. A liquid chromatography with tandem mass spectrometry method was developed and validated to detect pymetrozine in cauliflower. The samples were extracted using 20 mL of acetonitrile and purified with dispersive solid‐phase extraction using C₁₈ as sorbent. The limit of quantification of pymetrozine was 0.008 mg/kg in cauliflower. The recoveries of the analyte were 82.04–95.18% with RSD <8.45%. The calibration curves for pymetrozine showed good linearities in the concentration range 0.004–2.0 mg/L with determination coefficients (R²) >0.999. Pymetrozine dissipated rapidly in cauliflower with a half‐life of <4 days. The terminal residues of pymetrozine were <0.008–0.0881 mg/kg in cauliflower at 7, 10 and 14 days after spraying from six sites. The routine washing process removed about half amount of the pymetrozine in cauliflower; the reduction ratios were 51.0–52.8%. The dietary risk assessment indicated that pymetrozine did not exhibit obvious dietary health risks in cauliflower when good agricultural practices were implemented.     

Analysis of mandipropamid residual levels through systematic method optimization against the matrix complexity of sesame leaves using HPLC/UVD

An analytical method was developed to detect mandipropamid residues in sesame leaves using high‐performance liquid chromatography–ultraviolet detection. Samples were extracted with acetonitrile and were prepurified using a solid‐phase extraction (SPE) cartridge with an additional dispersive‐SPE (d‐SPE) sorbent application. The method was validated using an external calibration curve prepared using pure solvent. The linearity was excellent with determination coefficient = 1. The limits of detection and quantification were 0.003 and 0.01 mg/kg, respectively. Recoveries at three spiking levels – 0.1, 0.5, and 1.0 mg/kg – were in the range 80.3–90.7% with relative standard deviations <2%. This method was applied to field‐treated samples collected from two different areas, Gwangju and Muan, in the Republic of Korea and the half‐lives were similar, 5.10 and 5.41 days, respectively. The pre‐harvest residue limit was also predicted for both sites. The proposed method is sensitive and able to quantify trace amounts of mandipropamid in leafy vegetables. The combination of SPE and d‐SPE effectively removed the matrix components in sesame leaves. Copyright © 2015 John Wiley & Sons, Ltd.     

Enantioselective determination of triazole fungicide tebuconazole in vegetables,fruits, soil and water by chiral liquid chromatography/tandem mass spectrometry

A novel and sensitive method was developed for the determination of tebuconazole enantioselectively using reversed‐phase LC‐MS/MS. The separation and determination were performed using on an amylose‐based chiral stationary phase, a Lux 3u Amylose‐2 column (150 mm×2.0 mm), under isocratic conditions at 0.3 mL/min flow rate. A series of chiral stationary phases were investigated and the effect of mobile phase composition on the enantioseparation was discussed. Parameters including the matrix effect, linearity, precision, accuracy and stability were evaluated. Under optimal conditions, the overall mean recoveries for two enantiomers from the soil, tomato, cucumber, pear and apple samples were 79.3–101.1% with 2.8–11.5% intra‐day relative standard deviations (RSDs) and 4.1–8.6% inter‐day RSDs at 5, 25 and 50 μg/kg levels; the mean enantiomer recoveries from the water samples were 89.6–101.9% with 3.3–10.2% intra‐day RSDs and 5.1–7.7% inter‐day RSDs at 0.25, 0.5 and 2.5 μg/kg levels. The limits of detection (LODs) for all enantiomers in tomato, cucumber, pear, apple, soil and water were less than 0.6 μg/kg, whereas the limit of quantification (LOQ) did not exceed 2.0 μg/kg. The results indicate that this proposed method is convenient and reliable for the enantioselective determination of tebuconazole enantiomers in foods and environment samples.     

Enantioselective separation and determination of the dinotefuran enantiomers in rice,tomato and apple by HPLC

An effective chiral analytical method was developed for the resolution and determination of dinotefuran enantiomers in rice, tomato and apple samples. Dinotefuran enantiomers were baseline‐separated and determined on a novel chiral column, ChromegaChiral CCA, with n‐hexane–ethanol–methanol (85:5:10, v/v/v) as the mobile phase at a flow rate of 1.0 mL/min with UV detection at 270 nm. The resolution of dinotefuran enantiomers was about 1.8. The first eluted enantiomer was (+)‐dinotefuran and the second eluted one was (?)‐dinotefuran. The effects of mobile‐phase composition and column temperature on the enantioseparation were evaluated. The method was validated for linearity, repeatability, accuracy, LOD and LOQ. LOD was 0.15 mg/kg in rice and tomato, 0.05 mg/kg in apple, with an LOQ of 0.5 mg/kg in rice and tomato, 0.2 mg/kg in apple. The average recoveries of the pesticide from all matrices ranged from 75.8 to 92.9% for all fortification levels The precision values associated with the analytical method, expressed as RSD values, were <16.5% for the pesticide in all matrices. The methodology was successfully applied for the enantioselective analysis of dinotefuran enantiomers in real samples, indicating its efficiency in investigating the environmental stereochemistry of dinotefuran in food matrix.     

Analysis of Pesticide Residues by QuEChERS Method and LC-MS/MS for a New Extrapolation of Maximum Residue Levels in Persimmon Minor Crop

According to EU guidance SANCO/7525/VI/95 Rev. 10.3, residue data extrapolation from a surrogate major crop to a minor crop can be used for setting maximum residue levels (MRLs) with a reduced number of residue trials and representative selected pesticides. In this work, a QuEChERS method (citrate-buffered version and PSA with MgSO₄ clean-up) and LC-ESI-MS/MS for the determination of boscalid, pyraclostrobin, fludioxonil, fluopyram and tebuconazole in persimmon was developed and validated according to EU Commission guidelines and afterwards used for the determination of residues in four field trials. Residue levels at harvest for each pesticide ranged between 0.347 and 0.028 mg/kg. After comparing EFSA residue data on apples, as the surrogate major crop, and conducting a consumer risk assessment, a proposal of residue data extrapolation to set MRLs in persimmons was performed. The results showed that pesticide residues in persimmons at harvest were consistently lower than residues in apples when substances were applied according to the same critical GAP. MRLs were set at 0.5 mg/kg for fludioxonil, 0.6 mg/kg for boscalid, 0.3 mg/kg for tebuconazole, 0.4 mg/kg for fluopyran and 0.3 mg/kg for pyraclostrobin. The ratio of the MRLs for apple/persimmon varied between 2.5 for boscalid and 1.25 for fluopyram, suggesting that residue extrapolation can be feasible, promoting the process of pesticide registration for minor crops and the settlement of MRL.