超高效液相色谱-串联质谱法测定白芷中51种禁用农药的残留量

将白芷药材粉碎至通过孔径为(250±9.9)μm的网筛,并称取此白芷粉末样品2.00g于聚丙烯管中与水10mL混匀,再加入含1%(体积分数)乙酸的乙腈10.0mL,涡旋1min后加入无水硫酸镁4g和乙酸钠1g,剧烈振荡3min,离心5min,取其上清液5.0mL置于已盛有无水硫酸镁900mg、N-丙基乙二胺(PSA)450mg和硅胶300mg的净化管中,剧烈振荡5min使净化完全,离心5min。移取上清液3.0mL于40℃水浴中减压蒸缩至近干。加入50μg·L^-1的磷酸三苯酯内标溶液300μL,加入乙腈定容至1.0mL,经0.20μm滤膜过滤,取其滤液,按仪器工作条件进行超高效液相色谱-串联质谱法分析。选用Eclipse Plus C18色谱柱和以不同比例的(A)含10mmol·L^-1甲酸铵的0.1%(体积分数)甲酸溶液和(B)乙腈的混合液为流动相,按梯度洗脱程序对白芷中可能残留的51种禁用农药进行色谱分离,并在电喷雾离子源正、负离子(ESI+和ESI-)电离方式和动态多反应监测(dMRM)模式条件下进行串联质谱法测定。采用基质匹配标准曲线法定量。51种农药的质量浓度在一定范围内与其对应的峰面积呈线性关系,并测得其检出限(3S/N)为0.3~5.0μg·kg^-1。标准加入法回收试验的结果显示,其中大部分农药的回收率在71%以上,测定值的相对标准偏差(n=6)均小于20%。按此方法分析了70批白芷样品,共检出16种农药,其中甲拌磷亚砜的检出率达95%,最高检出量为15.2μg·kg^-1;甲拌磷砜和毒死蜱的检出率均为10%,最高检出量依次为3.5,45.0μg·kg^-1,其余13种农药的检出率均低于5%,且检出量均较低。     

Residue and Risk Assessment of Fluopyram in Carrot Tissues

This study describes the variation in residue behavior of fluopyram in soil, carrot root, and carrot leaf samples after the application of fluopyram (41.7% suspension, Bayer) by foliar spray or root irrigation at the standard of 250.00 g active ingredient per hectare (a.i./ha) and double-dose treatment (500.00 g a.i./ha). Fluopyram and its metabolite fluopyram-benzamide were extracted and cleaned up using the QuEChERS method and subsequently quantified with LC-QQQ-MS/MS. The LOD and LOQ of the developed method were in the range of 0.05–2.65 ug/kg and 0.16–8.82 ug/kg, respectively. After root irrigation, the final residues detected in edible parts were 0.60 and 1.80 mg/kg, respectively, when 250.00 and 500.00 g a.i./ha were applied, which is much higher than the maximum residue limit in China (0.40 mg/kg). In contrast, after spray application, most of the fluopyram dissipated from the surface of carrot leaves, and the final residues in carrot roots were both only 0.05 mg/kg. Dietary risk assessments revealed a 23–40% risk quotient for the root irrigation method, which was higher than that for the foliar spray method (8–14%). This is the first report comparing the residue behavior of fluopyram applied by root irrigation and foliar spray. This study demonstrates the difference in risk associated with the two application methods and can serve as a reference for the safe application of fluopyram.     

农药化学现状和发展动向

本文介绍农药化学现状,并与医药化学的研究特点进行比较。近年农药研究比较活跃的领域有天然农药、原农药、手性农药等。在新农药创制中发展较快的有超高效农药、特异性农药(生物调节剂),元素有机农药和复配农药,最后对农药化学展望作一概述。     

用毛细管色谱柱分离有机磷农药

本文介绍了用SE-30毛细管柱、高速率程序升温分离13种有机磷农药。其分离效果较好,分析速度较快,有良好的线性关系和重复性。     

Determination of organophosphorous pesticides in water using in-syringe ultrasound-assisted emulsification and gas chromatography with electron-capture detection

An in-syringe ultrasound-assisted emulsification microextraction (USAEME) was developed for the extraction of organophosphorus pesticides (OPPs) from water samples. The OPPs subsequently analyzed gas chromatography (GC) using a microelectron capture detector (μECD). Ultrasound radiation was applied to accelerate the emulsification of μL-level low-density organic solvent in aqueous solutions to enhance the microextraction efficiency of OPPs in the sample preparation for GC-μECD. Parameters affecting the efficiency of USAEME, such as the extraction solvent, solvent volume, pH, salt-addition, and extraction time were thoroughly investigated. Based on experimental results, OPPs were extracted from a 5 mL aqueous sample by the addition of 20 μL toluene as the extraction solvent, followed by ultrasonication for 30 s, and then centrifugation for 3 min at 3200 rpm, offered the best extraction efficiency. Detections were linear in the concentration of 0.01–1 μg/L with detection limits between 1 ng/L and 2 ng/L for OPPs. Enrichment factors ranged from 330 to 699. Three spiked aqueous samples were analyzed, and recovery ranged from 90.1% to 104.7% for farm-field water, and 90.1% to 101.8% for industrial wastewater. The proposed method provides a simple, rapid, sensitive, inexpensive, and eco-friendly process for determining OPPs in water samples.     

Sensitive determination of diuron on zinc oxide nanoparticles modified carbon paste electrode in soil and water samples

An electrochemical sensor based on Zinc oxide nanoparticles (ZnONPs) modified carbon paste electrode was designed for the toxic diuron pesticide detection. The ZnONPs were synthesized through the hydrothermal route and their structural properties were investigated via scanning electron microscopy (SEM) and X-ray diffraction powder (XRD). The designed ZnONPs-modified carbon paste electrode (ZnONPs-CPE) was characterized using cyclic voltammetry and electrochemical impedance spectroscopy. The sensor showed significantly enhanced sensitivity on the diuron oxidation peak current, compared to the bare carbon paste electrode. Qualitative and quantitative analysis were performed using cyclic voltammetry (CV) and square wave voltammetry (SWV). Experimental parameters such as pH, amount of ZnONPs and frequency were evaluated and the optimized conditions were obtained with 0.1 M phosphate buffer solution at pH=8, a frequency of 50 Hz and a quantity of 5 mg of ZnONPs. Under these conditions, linear responses ranging from 1.3 to 7.7 μM and 8.6 to 30 μM of diuron were obtained, with correlation coefficients of R²=0.994 and 0.996 respectively. Detection and quantification limits of 0.22 μM and 0.84 μM (S/N=3) were respectively achieved based on the 3σ method. The interference of some ions on the oxidation peak of diuron on ZnONPs-CPE was also evaluated and no interference was observed, therefore demonstrating the selectivity of the sensor. The proposed sensor, designed with ecofriendly materials, is sensitive, selective and was effectively used for diuron determination in soils and water samples with recoveries ranging from 98 % to 101.5 %.     

杀菌剂福美双的电化学性质及线性扫描溶出伏安法测定

提出了线性扫描溶出伏安法测定福美双的电分析化学方法.在 pH 5.0 HAc-NaAc缓冲溶液中福美双在汞电极上出现一还原峰,峰电位为-610 mV(vs.Ag/AgCl).采用各种电化学技术如循环伏安法和线性扫描溶出伏安法等对本体系进行研究,发现采用线性扫描溶出伏安法能得到较灵敏的还原峰,呈现不可逆电极反应现象,并具有一定的吸附性,在210 s时能达到吸附平衡.选择吸附时间为180 s时,线性范围为0.02～0.14 μg·mL-1,最低检测限为9.5 ng·mL-1.将本方法用于实际样品的测定,得到满意的结果.     

超高效液相色谱-四极杆-飞行时间质谱法快速筛查辣椒粉中27种农药残留

建立了超高效液相色谱-四极杆-飞行时间质谱（UPLC-Q-TOF/MS）快速筛查辣椒粉中27种农药残留的检测方法。样品采用乙腈提取,经Carb/NH₂固相萃取小柱净化,用乙腈-乙酸乙酯（3：1,v/v）洗脱,电喷雾正离子模式检测。在一级质谱模式下,以目标物的保留时间、精确质量数、同位素分布和同位素丰度比定性,以准分子离子峰的峰面积定量。在Targeted MS/MS模式下,通过相应碰撞能量下的离子碎片信息进一步确证。27种化合物在各自的线性范围内线性关系良好,相关系数均大于0.997。27种化合物的定量限为2.5~5.0 μg/kg,在3个添加水平下的回收率为72.3%~118.9%,相对标准偏差（RSD）为0.21%~12.7%（n=6）。该方法快速、灵敏、准确,适用于辣椒粉中多种农药残留的同时检测。     

Voltammetric determination of mesotrione at hanging mercury drop electrode

A study of the electrochemical reduction of the mesotrione pesticide on a hanging mercury drop electrode (HMDE) was performed as a basis for the development of a sensitive analytical method for natural samples. The electrochemical characteristics of herbicide mesotrione dissolved in a phosphate buffer (pH 7.0) have been determined by means of electrochemical techniques such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV) over a wide range of pH from 2.0 to 10.0. The experimental parameters, such as electrolyte type and its pH, pulse amplitude, and scan rate were optimized. The method was applied to the determination of the pesticide in a spiked soil samples. Using this method, a linear calibration curve for mesotrione was obtained up to the 0.1 μM range in pH 7 phosphate buffer solution with a detection limit (S/N = 3) of 50 nM. The method can be applied successfully to the determination of mesotrione in soils. The text was submitted by the authors in English.     

基于QuEChERS净化/气相色谱法测定蔬菜及水果中16种有机氯农药残留

该文建立了蔬菜及水果中16种有机氯农药残留的QuEChERS净化/气相色谱快速检测方法.样品经1％冰乙酸乙腈处理,QuEChERS净化,气相色谱分离后,以色谱峰保留时间定性,外标法定量.结果表明:16种有机氯农药在2.0～100 pg/L质量浓度范围内的线性关系良好,相关系数均大于0.99,检出限为0.16～2.90 ...