Simultaneous determination of oxathiapiprolin and two metabolites in fruits, vegetables and cereal using a modified quick, easy, cheap, effective, rugged, and safe method and liquid chromatography coupled to tandem mass spectrometry

Develop an external standard method for high-flux determination of veterinary drug residues liquid milk without solid phase extraction

To get rid of the singularity of the detection of veterinary drug residues in liquid milk, a high-throughput determination was developed for 126 VDRs in 17 categories in liquid milk based on the one-step extraction coupled with LC-HRMS (UPLC-Q-Exactive-Orbitrap-MS). The results showed that adding 2.5 mL of 0.1 mol/L Na2EDTA-McIlvaine in acetonitrile-methanol extractant (50:50, V/V) could effectively improve the response intensity of veterinary drug residues in liquid milk, reduce the matrix effect and eliminate the need for expensive SPE purification. The established external standard quantitative method has a LOD of 0.01-0.30 μg/L for all categories of veterinary drug residues, good linearity in the concentration range of LOQ of 0.03-1.00 μg/L, and correlation coefficients (r2) were all greater than 0.995. The spike recoveries at all three levels were between 80.30% and 119.95%. The positive detection rate of this method in 128 actual samples was 8.59%.

Investigating Six Common Pesticides Residues and Dietary Risk Assessment of Romanian Wine Varieties

The food and environmental safety debate extends to the use of pesticides in agriculture including the wine sector, which is one of the most intensive pesticide users across the agricultural sector. Pesticide utilisation is a common agricultural practice to protect fruits and plants from pathogens and insects while maintaining high production levels. Grapevine is generally a crop that is subject to intensive phytosanitary treatments, and therefore, it can be assumed that pesticide residues will accumulate in the vine-shoots and, later on, end up in the grapes and wines. The aim of this study was to determine the pesticide content in red, rosé, and white wines after phytosanitary treatments applied in the vineyard and their impact on long-term dietary risks. The following six pesticides were analysed: oxathiapiprolin, myclobutanil, iprovalicarb, tebuconazole, chlorantraniliprole, and acetamiprid. Samples were extracted using the QuEChERS (quick, easy, cheap, effective, rugged, and safe) method and analysed for the residues of pesticides by liquid chromatography-tandem mass spectrometry. Results indicated that the observed pesticides in the wine samples ranged between 0.05 and 0.75 ng/g. Dietary risks due to pesticide residues for women and men were evaluated using the estimated daily intake (EDI), hazard quotient (HQ), and hazard index (HI) of wines. The HQs and HIs did not surpass the 1 value (HQ, HI < 1) for both women and men, denoting that the concentrations of pesticide residues in these wine samples do not pose any immediate risk to consumers. Moreover, a pesticide residue intake model (PRIMo) model analysis was conducted, and the results suggest that European adult consumers have a low pesticide residue intake due to moderate wine consumption. However, pesticide residue intakes have been associated with several human health problems and high toxicity levels, therefore reliable analytical methods to monitor their presence in horticultural crops is crucial for clean and safe food products and healthy consumers.

Residue analysis and dietary exposure risk assessment of acibenzolar-S-methyl and its metabolite acibenzolar acid in potato, garlic, cabbage, grape and tomato

Acibenzolar-S-methyl (ASM) is one of the most effective plant resistance activators and protects against a broad spectrum of fungal, bacterial and viral pathogens. A rapid, efficient and high-throughput analysis method for ASM and its metabolite acibenzolar acid in fruits and vegetables was developed using potato, garlic, cabbage, grape and tomato as representative commodities by modified QuEChERS and UPLC-MS/MS. The modified procedure showed satisfying recoveries (70-108%) fortified in the range of 0.01-1 mg/kg with relative standard deviations (RSDs) lower than 17.7%. With the established analytical method, the dietary risk of ASM in fruits and vegetables from Chinese markets were further monitored using risk quotient (RQ) method. The RQ value based on ASM residue in China are far less than 1, elucidating that the potential health risk induced by ASM ingestion for Chinese population is not significant. Comparing the residue and risk assessment results of ASM in agricultural products in China to those in Codex, the maximum residue limits (MRLs) for ASM on garlic, cabbage and tomato established by CAC (Codex Alimentarius Commission) can be safely adopted in China, whereas the MRLs on potato and grape in China should be proposed as 0.01 mg/kg.

Mobility of Oxathiapiprolin and Mefenoxam in Citrus Seedlings After Root Application and Implications for Managing Phytophthora Root Rot

Oxathiapiprolin is highly effective in the management of Phytophthora root rot of citrus; however, its uptake into plants after soil application is not known. This was investigated and compared with mefenoxam using potted citrus seedlings sampled 7, 10, 13, and 16 days after soil treatments. Bioassays and high-performance liquid chromatography tandem mass spectroscopy (HPLC-MS/MS) were used to quantify fungicide amounts in plant extracts. Distinct inhibition zones of mycelial growth of Phytophthora citrophthora were observed in bioassays when root, stem, or leaf extracts were added to filter paper disks on agar plates. Based on the two quantification methods, concentrations of both fungicides in the three tissue types and at all sampling times were above the mean effective concentration that provides 50% growth reduction values of the baseline sensitivities. Relative concentrations at the four sampling times sometimes varied between the two methods but, for both methods, concentrations of oxathiapiprolin were significantly higher in roots and leaves as compared with stems 10 days after treatment and statistically similar in the three tissues after 7 days. For mefenoxam, concentrations significantly increased in roots between 7 and 16 days after treatment and were significantly the highest in roots as compared with stems or leaves 16 days after treatment. Regressions of oxathiapiprolin and mefenoxam concentrations using HPLC-MS/MS on those calculated from bioassay standard curves indicated that the bioassays overestimated fungicide amounts in the extracts. The bioassay, however, can be considered an alternative option comparable with costly residue analyses in fungicide mobility studies in plants. Uptake of oxathiapiprolin at sufficient but low concentrations into plant roots provides an explanation for its long-lasting high activity in the management of Phytophthora root rot.

Enantioselective residue analysis of oxathiapiprolin and its metabolite in tea and other crops by ultra-high performance liquid chromatography-tandem mass spectrometry

Oxathiapiprolin is the first chiral piperidinyl thiazole isoxazoline fungicide developed to control downy mildew and other diseases, and there were no prior reports on its enantiomeric residue. In this study, a modified quick, easy, cheap, effective, rugged, and safe extraction and purification method followed by ultra-high performance liquid chromatography-tandem mass spectrometry determination was first developed and validated for the residue analysis of oxathiapiprolin enantiomers and its metabolite IN-E8S72 in green tea and other crops. Oxathiapiprolin enantiomers and IN-E8S72 were separated on a chiral Lux Cellulose-3 column with the use of 0.1% formic acid in acetonitrile and 5 mmol/L ammonium acetate in water as mobile phases. IN-E8S72 was eluted first, followed by (-)-oxathiapiprolin, and then (+)-oxathiapiprolin. The recoveries ranged from 53.3 to 125.3% with relative standard deviations ranging from 1.4 to 16.0%. The limits of quantification for (-)-oxathiapiprolin and (+)-oxathiapiprolin were 0.005 mg/kg in romaine lettuce, head cabbage, potato, grape, and garlic, 0.01 mg/kg in soybean and pea, and 0.025 mg/kg in green tea and dry pepper. The limits of quantification of IN-E8S72 were twice those of (-)-oxathiapiprolin. Screening results with real market samples indicated that there was no enantiomeric excess in the oxathiapiprolin residue in romaine lettuce.

Residue Analysis and Risk Assessment of Oxathiapiprolin and Its Metabolites in Cucumbers under Field Conditions

In this study, a rapid, sensitive, and selective method was established for the detection of oxathiapiprolin and the metabolite IN-E8S72, as well as its glucose conjugate IN-SXS67 in cucumber using modified QuEChERS procedure combined with HPLC-MS/MS. The LOQs for all compounds were 0.02 mg kg^-1, and the average recoveries were 77.4-111.3% with RSDs of 1.0-8.5%. Under the optimized conditions, the established method was successfully used to determine field samples in dissipation and terminal residue studies. The dissipation study results showed that oxathiapiprolin dissipated rapidly in cucumber with half-lives of 2.4-4.0 days. On the basis of the terminal residue results, the risk assessment was conducted, and both the international estimated daily intake (IEDI) or national estimated daily intake (NEDI) of oxathiapiprolin were much less than 100% which indicate a low health risk to consumers. This work provides guidance for establishing MRL of oxathiapiprolin in China and is of great significance for evaluating its dietary risk in cucumber.

Dynamic modeling of famoxadone and oxathiapiprolin residue on cucumber and Chinese cabbage based on tomato and lettuce archetypes

We analyzed the uptake and distribution of two pesticides (famoxadone and oxathiapiprolin) in herbaceous vegetables (cucumber and tomato) and leafy vegetables (Chinese cabbage and lettuce) to test the viability of applying existing archetypes in the dynamic plant uptake model dynamiCROP to modeling pesticide residue in other crops. Using field data and modeling, we showed that tomato was an unsuitable match for cucumber (R2 of 0.5325-0.6862) though lettuce was a good fit for Chinese cabbage (R2 of 0.8649-0.8862). We then used our cucumber data to add this as a new crop species archetype in dynamiCROP; further tests proved the accuracy of this approach (R2 of 0.8097-0.9152). In addition, we analyzed the distribution, uptake, and translocation of the two pesticides in cucumber and Chinese cabbage, using the model to better understand the mechanisms of pesticide residues over time and evaluate potential human exposure to pesticide residues from consumption of these crops. The fractions of famoxadone and oxathiapiprolin eventually ingested by humans based on our field trials ranged from 10-4 to 10-3 kg intake kg applied-1; that is, per kilogram of pesticide applied, humans would eventually consume less than one gram.

Method Development and Validation of Indaziflam and Its Five Metabolites in Soil, Water, and Fruits by Modified QuEChERS and UHPLC-MS/MS

A method for simultaneously determining indaziflam and its five metabolites in soil, water, and fruits using ultraperformance liquid chromatography/tandem mass spectrometry was established. The analytes were eluted in <4.5 min. Positive electrospray ionization mode was used. The analytes were extracted using acetonitrile containing 1% ammonium hydroxide, and then the extracts were purified using octadecylsilane and PRiME HLB cartridges. The quantification limits were 0.01-1.01 μg kg^-1. The linearities of the calibrations for all analytes were excellent ( R² > 0.9952). The recoveries at spike concentrations of 0.01, 0.1, and 1 mg kg^-1 were 81.3-112.1%. The intraday and interday relative standard deviations were <13.5% and <12.3%, respectively. The method was successfully used to determine indaziflam and its five metabolites in samples from markets and fields. The results confirmed that the method is an effective and robust procedure for routinely determining indaziflam and its metabolites in soil, water, and fruit samples.

Measured and Modeled Residue Dynamics of Famoxadone and Oxathiapiprolin in Tomato Fields

A reliable analytical method for the simultaneous determination of famoxadone and oxathiapiprolin dissipation kinetics as well as the metabolites of oxathiapiprolin (IN-E8S72 and IN-WR791) in tomato and soil was developed. We studied the dissipation of famoxadone and oxathiapiprolin in tomatoes grown using different kinetic curves in the area of Beijing in 2015 and 2016. Our results show that the most suitable model for two fungicides in 2015 and 2016 was first-order kinetic and second-order kinetic with the half-lives of 3.4 to 5.2 and 2.4 to 3.0 days, respectively. In addition, we applied the dynamic plant uptake model dynamiCROP and combined it with results from the field experiments to investigate the uptake and translocation of famoxadone and oxathiapiprolin in the soil-tomato environment. Modeled and measured results of two years fitted well with R² values ranging from 0.8072 to 0.9221. The fractions of famoxadone and oxathiapiprolin applied during tomato cultivation that are eventually ingested by humans via residues in crop harvest were finally evaluated and found to be in the range of one part per thousand, that is one gram intake per kilogram applied.

Pseudoperonospora cubensis in China: Its sensitivity to and control by oxathiapiprolin

The novel fungicide oxathiapiprolin has potential for the control of downy mildew of cucumber, which is caused by Pseudoperonospora cubensis. In this study, an in vitro bioassay with detached leaves was used to determine the baseline sensitivity to oxathiapiprolin for 77 Ps. cubensis isolates from 11 provinces in China. The baseline sensitivity curve was continuous, and the average EC₅₀ value was 2.23 × 10^-4 μg ml^-1. In field trials, the control of downy mildew of cucumber was greater with oxathiapiprolin at 20 or 30 g a.i. ha^-1 than with dimethomorph at 262.5 g a.i. ha^-1. Oxathiapiprolin was taken up by cucumber roots and transported upwards to stems and leaves. The full length of PscORP1, the gene that encodes the target protein of oxathiapiprolin in Ps. cubensis, was sequenced for the first time. Our results suggested that oxathiapiprolin will be an excellent alternative fungicide for control of cucumber downy mildew. However, as Ps. cubensis is a high-risk pathogen, resistance development to oxathiapiprolin should be monitored and managed.

Determination of oxathiapiprolin concentration and dissipation in grapes and soil by ultrahigh-performance liquid chromatography-tandem mass spectrometry

BACKGROUND

The residue concentrations and dissipation rate of a new oxathiapiprolin fungicide in grapes and soil were investigated to provide an evaluation for the safe use of oxathiapiprolin in grapes. Pesticide residue was extracted by acetonitrile, then purified by solid-phase extraction with an Envi-Carb cartridge and determined by ultrahigh-performance liquid chromatography-tandem mass spectrometry.

RESULTS

The fortified recoveries ranged from 85.2% to 99.0%, with relative standard deviations of 1.7-4.5%. The limit of quantitation for oxathiapiprolin in grapes and soil was 0.002 mg kg^-1 . The mean initial deposits of oxathiapiprolin in grapes were 0.345-0.565 mg kg^-1 , with half-lives of 8.6-9.2 days. The mean initial deposits of oxathiapiprolin in soil were 0.078-0.273 mg kg^-1 , with half-lives of 7.6-12.0 days. The oxathiapiprolin residue in grapes and soil was 0.002-0.022 mg kg^-1 and 0.002-0.123 mg kg^-1 when sampling 14 days after application, respectively.

CONCLUSION

The residue in the grapes was less than 0.01 mg kg^-1 when sampling 28 days after application, which suggested that the application rate of 20 mg a.i. kg^-1 for this fungicide should be used to ensure that treated grapes can be considered safe for humans to consume when sampling 28 days after the final application. © 2016 Society of Chemical Industry.

Translocation of Oxathiapiprolin in Bell Pepper Plants and Systemic Protection of Plants Against Phytophthora Blight

Production of bell pepper is seriously affected by Phytophthora capsici, the causal agent of Phytophthora blight. Limited approaches are available for effective management of the disease. Oxathiapiprolin is a fungicide recently registered in the United States that suppressed P. capsici and reduced Phytophthora blight on bell pepper significantly in our previous studies. It is unknown whether oxathiapiprolin translocates in bell pepper plants systemically after application. Experiments were conducted to determine uptake of oxathiapiprolin by bell pepper plants and its systemic movement in the plant. Quantification of oxathiapiprolin in plant tissues was conducted by high-performance liquid chromatography (HPLC) that detected the compound sensitively and selectively. Percentage of recovery of oxathiapiprolin from plant tissues was calculated by comparing the quantities in plant tissues determined by HPLC with known quantities of the compound added to the plant tissues. Recovery rates of oxathiapiprolin from pepper plant tissues ranged from 87.0 to 119.3%. When oxathiapiprolin was applied to roots of bell pepper plants grown in hydroculture, the compound was detected in the root within 4 h and in the cotyledon, first true leaf, and second true leaf within 8 h. It was detectable in the top new leaf 48 h after application to the root. In greenhouse studies with bell pepper plants grown in pots, oxathiapiprolin was applied as a soil drench at 100 and 400 μg/ml. The compound was detected in the root within 3 days and in the stem and first true leaf within 6 days when applied at 100 μg/ml. It was detected in the root, stem, first true leaf, and top new leaf within 3 days when applied at 400 μg/ml. Phytophthora blight on pepper foliage was significantly reduced when oxathiapiprolin was applied as a soil drench at 100 or 400 μg/ml under greenhouse conditions. This is the first report indicating systemic movement of oxathiapiprolin in pepper plants that provides useful information for designing fungicide application programs for effective management of the disease.

Analysis of Trace Quaternary Ammonium Compounds (QACs) in Vegetables Using Ultrasonic-Assisted Extraction and Gas Chromatography-Mass Spectrometry

A reliable, sensitive, and cost-effective method was developed for determining three quaternary ammonium compounds (QACs) including dodecyltrimethylammonium chloride, cetyltrimethylammonium chloride, and didodecyldimethylammonium chloride in various vegetables using ultrasonic-assisted extraction and gas chromatography-mass spectrometry. The variety and acidity of extraction solvents, extraction times, and cleanup efficiency of sorbents were estimated to obtain an optimized procedure for extraction of the QACs in nine vegetable matrices. Excellent linearities (R(2) > 0.992) were obtained for the analytes in the nine matrices. The limits of detection and quantitation were 0.7-6.0 and 2.3-20.0 μg/kg (dry weight, dw) in various matrices, respectively. The recoveries in the nine matrices ranged from 70.5% to 108.0% with relative standard deviations below 18.0%. The developed method was applied to determine the QACs in 27 vegetable samples collected from Guangzhou in southern China, showing very high detection frequency with a concentration of 23-180 μg/kg (dw).

A highly sensitive method for simultaneous determination of the quaternary ammonium pesticides chlormequat and mepiquat in pears and potatoes by modified QuEChERS-high performance liquid chromatography-tandem mass spectrometry

A highly sensitive HPLC-MS/MS method for simultaneous determination of the quaternary ammonium pesticides chlormequat (CQ) and mepiquat (MQ) in pears and potatoes was developed and fully validated.