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 ...     

Pesticide Residues in Vegetables and Fruits from Farmer Markets and Associated Dietary Risks

The use of pesticides leads to an increase in agricultural production but also causes harmful effects on human health when excessively used. For safe consumption, pesticide residues should be below the maximum residual limits (MRLs). In this study, the residual levels of pesticides in vegetables and fruits collected from farmers’ markets in Sharkia Governorate, Egypt were investigated using LC-MS/MS and GC-MS/MS. A total number of 40 pesticides were detected in the tested vegetable and fruit samples. Insecticides were the highest group in detection frequency with 85% and 69% appearance in vegetables and fruits, respectively. Cucumber and apple samples were found to have the highest number of pesticide residues. The mean residue levels ranged from 7 to 951 µg kg⁻¹ (in vegetable samples) and from 8 to 775 µg kg⁻¹ (in fruit samples). It was found that 35 (40.7%) out of 86 pesticide residues detected in vegetables and 35 (38.9%) out of 90 pesticide residues detected in fruits exceeded MRLs. Results for lambda-cyhalothrin, fipronil, dimothoate, and omethoate in spinach, zucchini, kaki, and strawberry, respectively, can cause acute or chronic risks when consumed at 0.1 and 0.2 kg day⁻¹. Therefore, it is necessary for food safety and security to continuously monitor pesticide residues in fruits and vegetables in markets.     

Advancement of Phenoxypyridine as an Active Scaffold for Pesticides

Phenoxypyridine, the bioisostere of diaryl ethers, has been widely introduced into bioactive molecules as an active scaffold, which has different properties from diaryl ethers. In this paper, the bioactivities, structure-activity relationships, and mechanism of compounds containing phenoxypyridine were summarized, which may help to explore the lead compounds and discover novel pesticides with potential bioactivities.     

Simultaneous Determination of Seven Pesticides and Metabolite Residues in Litchi and Longan through High-Performance Liquid Chromatography-Tandem Mass Spectrometry with Modified QuEChERS

This study established a QuEChERS high-performance liquid chromatography/tandem triple-quadrupole mass spectrometry method for determining azoxystrobin, pyraclostrobin, picoxystrobin, difenoconazole, chlorantraniliprole, imidacloprid, and cyantraniliprole and its metabolite (IN-J9Z38) in litchi and longan, and applied this method to the real samples. The residues in samples were extracted with acetonitrile and purified with nano-ZrO₂, C₁₈, and PSA. The samples were then detected with multireactive ion monitoring and electrospray ionization in the positive ion mode and quantified using the external matrix-matched standard method. The results showed good linearities for the eight analytes in the range of 1–100 μg/L, with correlation coefficients (r²) of >0.99. The limit of quantification was 1–10 μg/kg, and the limit of detection was 0.3–3 μg/kg. Average recovery from litchi and longan was 81–99%, with the relative standard deviation of 3.5–8.4% at fortified concentrations of 1, 10, and 100 μg/kg. The developed method is simple, rapid, efficient, and sensitive. It allowed the rapid screening, monitoring, and confirming of the aforementioned seven pesticides and a metabolite in litchi and longan.     

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.     

气相色谱法同时测定粮食中14种有机磷残留量

建立了气相色谱法同时测定粮食中14种有机磷农药残留的方法。样品经乙腈溶解,高速匀浆,振荡提取,离心浓缩定容,气相色谱外标法定性定量。敌敌畏等14种有机磷农药在DB-1701毛细管柱上得到了很好的分离,在浓度为0.05～2.00mg/L范围内线性关系良好,相关系数r为0.99～1.00,最低检出限为0.01～0.08mg/kg;当添加水平为0.100、0.500、1.000mg/kg 时,回收率为71.2%～113.1% ,相对标准偏差为2.2%～6.9%。方法简单、快速、准确、灵敏,适用于一般检验机构的日常检验需要。     

应用超高效液相色谱-四极杆-飞行时间质谱建立茶叶中农药残留的筛查与确证方法

基于超高效液相色谱-四极杆-飞行时间质谱(UPLC-QTOF-MS),使用UNIFI软件建立91种农药残留的筛查与确证方法,进行定性方法验证并应用于流通市场中茶叶的筛查检测。通过对收集的农药认证标准物质(CRM)分析,构建91种农药化合物的质谱数据库。样品经乙腈提取,固相萃取柱净化,Acquity BEH C18色谱柱分离,在MS^E模式下进行全信息采集(ESI+), UNIFI软件对数据进行匹配分析。设置保留时间最大偏差为±0.1 min,精确质量偏差阈值为±5×10^-6,可识别加合物形式包括[M+H]⁺、[M+Na]⁺、[M+K]⁺、[M+NH₄]⁺。参照SANTE/11813/2017指南进行定性方法学验证。在21份茶叶样品中添加混合标准溶液至4个水平(0.01、0.05、0.10、0.20 mg/kg),确定每种农药在茶叶样品中的筛查检出限(SDL),共评估了1 911种农药/样品组合。发现有66种农药的SDL为0.01 mg/...     

作为表面增强拉曼光谱基底的高度均匀Au纳米棒的构筑及对福美双的检测

采用种子生长法制备Au纳米棒(GNRs),随后进行组装和煅烧得到单层致密堆积的GNRs薄膜.在煅烧过程中,组装所需有机物在煅烧过程中分解,从而使得GNRs表面具有较高的清洁度.研究中发现,煅烧前后金纳米棒表面的间隙进一步提高,增强了其SERS(表面增强拉曼光谱)活性.为了研究其SERS活性,选择了2种探针分子以研究其灵...     

Determination of pesticides in dried minor tropical fruits from Colombia using the Quick,Easy, Cheap,Effective, Rugged,and Safe method‐gas chromatography–tandem mass spectrometry

The AOAC 2007.1 quick, easy, cheap, effective, rugged, and safe official method, together with gas chromatography coupled to a triple quadrupole mass spectrometer was applied for the analysis of 38 multiclass pesticides from dried fruits typically cultivated and exported from Colombia: uchuva (Physalis peruviana), lulo (Solanum quitoense), guanabana (Anona muricata), and pitahaya (Hylocereus undatus). The whole method was validated in terms of matrix‐matched calibration, matrix effect, and recovery using atrazine‐d₅ as internal standard, triphenylphosphate for quality control of the injection, and a proper mixture of analytes protectants. Matrix‐matched calibration data were found satisfactory for all pesticides and dried fruits, reporting R² values above 0.99. Matrix effect values evidenced the existence of such effect in most cases. The applied procedure gave satisfactory recovery percentages (70–120%) and relative standard deviation values (< 20%) for 92% of the 456 combinations pesticide/fruit studied (spiked levels of 25, 200, and 400 µg/kg). Finally, 20 real dried fruit samples were analyzed and residues of tebuconazole were found in two samples of uchuva at a concentration below the lowest calibration level of the method for one of them and at 10.8 ± 1.6 µg/kg for the other, being below or similar to the general maximum residue level established for monitoring purposes in food applications.     

A quenching fluoroimmunoassay for analysis of the pesticide propazine in an apolar organic solvent, reverse micelles of AOT inn-octane: Effect of the micellar matrix and labeled antigen structure

A simple way of directly observing antigen-antibody binding in a reverse micellar system,n-octane containing reverse micelles of aerosol OT (AOT), using the hydrophobic pesticide propazine as antigen, is described. We observed two processes during fluorescein-labeled propazine (FP)-antibody (Ab) interaction in reverse micelles: (1) quenching of the fluorescence of FP after mixing of Ab and FP (due immune complex formation) and (2) restoration of FP fluorescence after addition of excess propazine to the immune complex formed. We found that the quenching efficiency depends on both the properties of the reverse micellar system (surfactant concentration, hydration degreeW ₀ = [water]/[surfactant]) and the structure of the labeled antigen. A quenching fluoroimmunoassay of propazine both in apolar organic solvents and in water is developed. The method is homogeneous. The quenching time is 10–30 min, and the detection limit of propazine is 100 nM (20 Μg/L) in organic solvent and 10nM (2 Μg/L) in water. Propazine can be added to the reverse micellar system when dissolved in AOT/octane, or in an octane/chloroform mixture, or in chloroform. This makes possible the use of the analysis directly for pesticide extracts in nonpolar organic solvents.