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[学术文献 ] Polyamidoamine Dendrimer Modified Silica Nanoparticles: A Promising Sorbent for Benzoylurea Insecticides Detection in Tea Infusions 进入全文
Journal of the Brazilian Chemical Society 期刊
This research aims to develop a precise and efficient dispersive solid-phase microextraction (DSPE) technique using third-generation polyamidoamine (PAMAM) dendrimer-grafted nanoparticles to quantify benzoylurea pesticides in green tea, black tea, and oolong tea infusions. The extraction efficiency is optimized through single-factor adjustments of key parameters, including adsorbent quantity (5-20 mg), adsorption duration (5-20 min), desorbent identity (methanol, acetonitrile), volume (100-600 μL), sodium chloride concentration (0-10%, m/v), and sample solution pH (3-8). The optimized method demonstrates linearity in the range of 2-500 μg L-1, with limits of detection (LODs) ranging from 0.6-1.5 μg L-1 and limits of quantification (LOQs) from 2.0 5.0 μg L-1. Recovery rates of 81.2-96.0% are achieved, with intra-day relative standard deviations (RSDs) of 1.4-2.8% and inter-day relative standard deviations of 2.0-3.9%, indicating high accuracy and repeatability. The successful application of detecting residues in commercial tea samples underscores the strong potential of the technique to determine benzoylurea analyte levels.
[会议论文 ] Simultaneous Determination of 70 Pesticide Residues in Coffees by Gas Chromatography-mass Spectrometry 进入全文
IEEE 会议
An efficient and sensitive method for simultaneous determination of 70 pesticide residues in coffees has been established and validated. The multiresidue analysis of the pesticides in coffees involved extraction with ethyl acetate, clean-up using gel permeation chromatography (GPC) and solid-phase extraction (SPE), and subsequent identification and quantification of the selected pesticides by gas chromatography-mass spectrometry (GC-MS). and then quantified with an external standard method. Recoveries of pesticides ranged from 61% to 127% at the spiked level of 0.005-2.5 mg/kg, while the relative standard deviation was between 2% and 17%. In addition, the limits of determination (0.005 mg/kg to 0.5 mg/kg) revealed that simultaneous determination of multi-residues in coffees was possible.
[前沿资讯 ] Makaibari Tea Treasures: An Infusion of the Modern into a Cup of Tradition 进入全文
World Tea News 网站
Nestled in the lush arboreal hills around Kurseong in Darjeeling District, India, Makaibari Tea Estate has evolved from plantation to legacy. Founded in the 19th century, the estate is one of the oldest and most iconic in the region, admired not only for the quality of its fine teas, but also for its commitment to sustainability, community, and innovation. Particularly since the 1980s, Makaibari has grown from a traditional estate into a globally recognized brand, with its packaged teas symbolizing biodynamic farming, organic cultivation, and ethical labor practices. It appeared to be a universal practice for Darjeeling tea companies to establish their reputations with their best teas sold abroad, and offer far lower quality tea to domestic consumers. Times are changing, and Indians want to be able, even in smaller quantities, to buy the same tea sourced from within Indian borders that is kept on the shelf in foreign boutiques. Previously, export quality tea was unavailable to the retail customer in India. The shift in demand is one of the motivating factors behind Luxmi Estates, which owns Makaibari Tea Estate, to launch a quality enhancement and consistency drive for its new packaged teas, which the company has named, Makaibari Tea Treasures.
[学术文献 ] Rapid Determination of 36 Pesticide Residues in Tea Soup Using Dispersive Liquid–Liquid Microextraction Technology Based On Hydrophobic Fatty Acid Combined With Effervescent-Assisted Extraction 进入全文
Separation Science Plus 期刊
Tea is one of the most popular beverages in the world. In tea plant (Camellia sinensis) cultivation, the application of pesticides and herbicides constitutes a common agricultural practice for integrated pest management and weed control. Researchers usually focus on the pesticide residues in tea itself and rarely study the pesticide residues in tea soup. This study presents a rapid quantitative analysis method for detecting 36 common pesticides in green tea soup. The method involves using effervescent-assisted extraction combined with dispersive liquid–liquid microextraction. Pesticides in tea soup are extracted with nonanoic acid, and during the extraction process, sodium carbonate solution (Na2CO3 solution) and sulfuric acid (H2SO4) are added to produce carbon dioxide for auxiliary extraction. The solidified substances are then dissolved in methanol and analyzed using LC–MS/MS. This study revealed that the 36 target pesticides exhibited strong linear responses across a concentration range of 1–50 ng mL−1, with correlation coefficients (R2) exceeding 0.99. The developed method demonstrated a limit of quantification (LOQ) of 0.1 µg L−1, accompanied by recovery rates ranging from 76.3% to 101.4% and relative standard deviations (RSDs) below 6.7% across all validation parameters. This approach is cost-effective, minimizes the use of organic reagents, and reduces environmental pollution. Overall, the combination of effervescent-assisted extraction and dispersive liquid–liquid microextraction is efficient for detecting pesticides in tea soup, making it suitable for routine analysis of commonly used pesticides in green tea soup.
[学术文献 ] Residue behavior, processing factor and dietary risk assessment of flupyradifurone and its metabolites during tea cultivation to consumption 进入全文
Journal of Food Composition and Analysis 期刊
The dissipation behavior and safety assessment of the commercial insecticide Sivanto® (Flupyradifurone 200 g L⁻¹ SL) in tea cultivation have not been previously studied in India. This study evaluated residue levels in fresh tea leaves and processed tea through field trials. Flupyradifurone was applied at two concentrations, 150 g a.i. ha⁻¹ and 300 g a.i. ha⁻¹ , with two applications at a 10-day interval. A modified QuEChERS technique was used for the extraction and purification of flupyradifurone and its three metabolites. Liquid chromatography-mass spectrometry (LC-MS) was used for detection and quantification. The method was validated for precision, accuracy, and linearity, with a detection limit of 0.01 mg kg⁻¹ and a quantification limit of 0.02 mg kg⁻¹ . The recovery of flupyradifurone and its metabolites ranged from 83.3 % to 113.3 %. The estimated half-life of total residues in tea leaves was 1.6 days. Brew factor was recorded as 0.06 for green tea and 0.03 for black tea. The proposed maximum residue limits (MRLs) were 9.0 mg kg⁻¹ for green tea and 30.0 mg kg⁻¹ for black tea. Based on brew factors, long-term dietary risk assessments indicated no significant health concerns when applied at recommended levels.
[学术文献 ] Phloem Redistribution of Pesticide Phenamacril in Plants Followed by Extensive Biotransformation 进入全文
Environmental Science & Technology Letters 期刊
Here, we evaluated the uptake and biotransformation mechanism of the systemic fungicide phenamacril in hydroponic/soil–plant systems. Phenamacril was preferentially accumulated in shoots with the translocation factor up to 3.5 (or 6.9) in wheat (or rice) during 144 h of the uptake kinetic experiment. Apart from upward xylem translocation, phenamacril could also be redistributed from shoots to roots (0.4%) through phloem transport and then released into the rhizosphere surrounding solution (1.7%) through plant excretion via a split-root experiment. Then, 76.4% (or 70.4%) of phenamacril was transformed to 14 (or 12) metabolites in hydroponic-wheat (or hydroponic-rice) systems after 28 days of exposure, with nine of them first identified based on nontarget analysis. The proposed metabolic pathways included hydroxylation, hydrolysis, isomerization, dehydrogenation, deamination, dehydration, decarboxylation, reduction, and conjugation reactions, which were modulated by genes overexpression of metabolic enzymes (e.g., cytochrome P450). Notably, metabolite M-157 was predicted to be more persistent in environments and more toxic to rats and aquatic organisms than phenamacril by theoretical calculation. This study highlights that phloem transport and plant excretion may result in cycling chemical contamination, and the transformation products may possess elevated toxicities, thus should be considered in estimating the contamination of pesticides in crops and environments.
