固相萃取/气相色谱-质谱法测定海水中16种除草剂

建立了同时测定海水中16种除草剂的气相色谱-质谱检测方法。样品用固相萃取仪过HLB柱浓缩、净化,洗脱液氮吹至近干,乙酸乙酯定容,用气相色谱质谱仪选择离子监测模式(SIM)进行检测,外标法定量。该方法中草净津、二甲戊乐灵的检出限为10.0 ng/L,其余14种除草剂的检出限为5.0 ng/L;草净津、二甲戊乐灵的线性范围为4.0~200μg/L,其余14种除草剂的线性范围均为2.0~100μg/L;方法加标回收率为78.3%~115.0%,相对标准偏差为4.4%~9.9%。该方法操作简单,精确度高,适用于海水中16种除草剂的定性定量检测。     

Micro-porous membrane liquid-liquid extraction as an enrichment step prior to nonaqueous capillary electrophoresis determination of sulfonylurea herbicides

A method based on micro-porous membrane liquid-liquid extraction (MMLLE) enrichment and nonaqueous capillary electrophoresis (CE) separation, was established for the analysis of sulfonylurea herbicides in water samples. After MMLLE, the analyte trapped in the chloroform was treated mildly with nitrogen flow to dryness and then dissolved in 200 μl of 4 mM Tris methanol solution for CE analysis. Five sulfonylurea herbicides were separated by nonaqueous CE with Tris/acetate of methanol solution as the run buffer. MMLLE related parameters such as organic solvent used as acceptor, sample flow rate, sample pH, enrichment time, and salt effect were investigated with tribenuron methyl (TBM) as a model compound. Results showed that with a sample flow rate of 3.0 ml min⁻¹ and an enrichment time of 20 min, the proposed method has good linear relationship over the scope of 1-15 ng ml⁻¹ with related coefficient of R²=0.9911, and a detection limit of 0.4 ng ml⁻¹. This method was applied to determine TBM in realworld water samples with recoveries over the range of 89-97%.     

Automatic measurement of bentazone and phenoxy acid herbicides by HPLC with three different detectors

Summary An automated procedure is described for the simultaneous UV, fluorescence and electro chemical detection in series of bentazone and six phenoxy acid herbicides. A two step liquid-liquid extraction with dichloromethane giving an enrichment about a thousand fold has been used. Recovery rates after enrichment and detection limits of bentazone, 2,4 D, 2,4 DB, MCPA, MCPB, MECOPROP and DICHLORPROP in river water are given. It is concluded that the herbicides examined can be detected at levels between 20 ngl^–1 without the necessity of derivatisation.     

含十五内酯环磺酰脲类化合物的合成

为模拟天然产物的结构, 以α-硝基环十二酮为原料, 通过与丙烯醛的Michael加成、扩环和引入磺酰脲的侧链, 合成了五个含十五内酯环的磺酰脲类化合物4. 它们的结构均通过¹H NMR, IR和元素分析确证. 生测结果表明它们均具有一定的除草活性. 其中以4c的活性最高, 对马唐和苘麻的LC₅₀分别为27.4和71.8 mg/L.     

Characterization and prediction of retention in gradient-elution normal phase HPLC with ternary gradients

Summary Chromatographic behaviour of phenylurea herbicides and phenols on a silica gel column with ternary gradient elution using mobile phases containing dry 2-propanol, n-heptane and dioxane was investigated. With dried solvents and the temperature controlled to ±0.1 °C, the data from repeated experiments measured on the same column after ten months of use were reproducible. Algorithms were suggested for characterization and prediction of retention in ternary gradients at a constant ratio of the two polar solvents (elution strength gradients) and at a constant sum of their concentrations (selectivity gradients). These were based on two- and three-parameter equations describing the dependence of the sample retention factors (isocratic) on the concentration of the polar solvent in binary mobile phases. Presented at the 21^st ISC held in Stuttgart, Germany, 15^th–20^th September, 1996     

MIL-53(Fe)@聚多巴胺@Fe_3O_4磁性复合材料的制备及其用于环境水样中磺酰脲类除草剂的磁固相萃取

制备了MIL-53(Fe)和聚多巴胺(PDA)修饰的磁性Fe_3O_4复合材料MIL-53(Fe)@PDA@Fe_3O_4,并将其作为吸附剂用于磁固相萃取-高效液相色谱法(MSPE-HPLC)检测环境水样中4种磺酰脲类除草剂(甲嘧磺隆、苄嘧磺隆、吡嘧磺隆和氯嘧磺隆)。实验优化了高效液相色谱条件(乙腈和含0.01%(体积分数)三氟乙酸的水溶液为流动相进行梯度洗脱,检测波长为233 nm)及磁固相萃取条件(洗脱剂为5 mL丙酮,萃取时间为4.5 min,吸附剂用量为60 mg,NaCl加入量为0.5 g,溶液pH值为3),在最佳条件下进行方法学考察,4种磺酰脲类除草剂均得到良好的线性关系,相关系数(r)≥0.998 0。方法的检出限(LOD,S/N=3)为0.28~0.77μg/L。将建立的方法用于3种环境水样中4种磺酰脲类除草剂的检测,其加标回收率为78.8%~109.7%。结果表明,制备的功能化复合材料结合了MIL-53(Fe)和Fe_3O_4的优点,可以简便快速地萃取分离环境水样中磺酰脲类除草剂。     

应用分子图形学、分子力学、量子化学及静电势研究农药分子结构与性能关系(Ⅸ)──结构参数及计算方法的选择对提高磺酰脲类除草剂活性预报准确性的影响

重点讨论对提高磷酰脲类除草剂分子活性预报准确性有明显影响的两方面因素──结构参数的选择和计算方法的应用．在选择结构参数时兼顾分子的局部活性基团效应和分子的整体性质，并运用了最优化计算方法──人工神经网络方法（ANN）．所得预报结果与实验值吻合较好（预测均方误差msc＝0．073），远优于多元回归所得的结果（msc＝0．82）．     

Determination of triazine herbicides in surface and drinking waters by off-line combination of liquid chromatography and gas chromatography-mass spectrometry

Summary Mass spectra of 12 triazines were obtained by electron impact (EI), positive-ion chemical ionization (PCI) and negative-ion chemical ionization (NCI) using methane and isobutane as reagent gases. EI mass spectrometry is more sensitive than PCI and NCI, although the chemical ionization modes increase selectivity markedly. A pre-column packed with polymer stationary phase was employed to preconcentrate surface and drinking water samples. After desorption of the analytes with ethyl acetate, an aliquot was injected directly into the GC-MS system. Atrazine and simizine were found in these samples at 10–80 ppt levels. The limits of detection for both herbicides were below 10 ppt in drinking water.     

高效液相色谱/质谱法测定土壤中10种磺酰脲类除草剂多残留

建立了高效液相色谱/质谱法(HPLC-MS)同时检测土壤中10种磺酰脲类除草剂多残留量的方法。样品在磷酸缓冲液(pH值7.8):甲醇(8∶2,V/V)中经超声波萃取,提取液直接经固相萃取小柱净化,采用HPLC-ESI( )-MS进行定性定量分析。比较了C leanert C18,C leannertHXN和Oasis HLB 3种SPE商品柱的净化效果,结果表明C leanert C18和C leannertHXN柱的净化效果和回收率均较好。10种磺酰脲类农药的液相色谱分离在乙腈-甲醇-水(0.2%冰醋酸)梯度洗脱下完成,10个化合物的保留时间在10~16 m in。10种磺酰脲类除草剂在0.1~10.0 mg/L范围内线性良好,相关系数均在0.9964~0.9989之间;相对标准偏差在0.99%~4.26%之间。在0.01~1.0 mg/kg添加水平范围内,平均添加回收率在80.2%~104.5%之间(除苯磺隆)。本方法中10种磺酰脲类除草剂在土壤中的检出限为0.6~3.5μg/kg之间。     

Gas chromatographic enantiomer separation of agrochemicals using modified cyclodextrins

The enantiomers of phenoxypropionic acid type herbicides have been resolved by capillary gas chromatography employing modified cyclodextrins as chiral stationary phases. Excellent separations were obtained with columns containing a 1:1 mixture of per-O-pentylated and per-O-methylated γ-cyclodextrin. The enantiomers of the methyl esters of mecoprop and dichlorprop were also resolved on octakis(3-O-butyryl-2,6-di-O-pentyl)-γ-cyclodextrin. On this phase the order of elution of the enantiomers was temperature-dependent, the elution order being reversed as the temperature passed through the isoenantioselective temperature. This is the first time such behavior has been observed with cyclodextrin derivatives. The enantiomers of the polychlorinated polycyclic pesticides cis- and trans-chlordane, oxychlordane, heptachlor, heptachlorepoxide, and three chiral organophosphorus pesticides could be resolved using selectively derivatized cyclodextrin derivatives.