三唑农药的手性拆分及对映体的转化

利用Chiralcel OJ-H和Chiralcel OD-H手性柱对烯唑醇、三唑酮和三唑醇的手性拆分进行了研究,进一步测定了烯唑醇和三唑酮对映体的旋光性质,据此确定了两种农药对映体的绝对构型,在此基础上结合三唑酮转化为三唑醇的还原实验确定了三唑醇4个对映异构体的绝对构型。考察了几种三唑农药在有机溶剂和缓冲溶液中的手性稳定性,其中三唑酮在甲醇、乙醇和水中存在明显的对映体转化行为,而烯唑醇和三唑醇则是手性稳定的,升高温度及碱性环境会加快三唑酮的对映体转化。     

Pollution Potential of Some Triazole Pesticides

Abstract

The widespread occurrence of pesticides, especially in the groundwater has stimulated research into the behavior of these agrochemicals in the environment. In this work a simple model to describe the fate of the two triazole fungicides Flutriafol and Flusilazol in a silt soil is presented. For this purpose we constructed mini-columns of soil, on which we applied the two fungicides, the percolation waters and the soils were collected at different times and the pesticides quantified in these samples. In the first part, these experiments were carried out outdoors during a period of 6 months on the silt soil and in a second part, we did similar indoor experiments with the same soil and with two others. To complete our work, we studied the adsorption of these two compounds on these three types of soil with batch equilibrium experiments. The results demonstrate that the fungicide Flusilazol is an immobile compound in soil, being strongly adsorbed whatever the nature of the soil. The Flutriafol is slightly to moderately mobile in the different soils, being less adsorbed.     

气相色谱-质谱法测定蔬菜与水果中11种三唑类农药残留

建立了蔬菜和水果中11种三唑类农药残留的气相色谱-质谱(GC - MS)测定方法.样品用乙腈均质提取,经石墨化炭黑/氨基复合柱净化,乙腈-甲苯(3:1)洗脱.洗脱液经浓缩、溶剂交换后定容,采用气相色谱-质谱的选择离子监测方式( GC - MSD/SIM)进行测定,内标法定量.方法的线性范围为0.05～5 ng,相关系数...     

阳离子交换净化/气相色谱-质谱法与气相色谱法测定蔬菜水果中15种三唑类农药残留

采用离子交换净化法,建立了蔬菜水果中15种三唑类农药残留测定的前处理方法。样品用乙腈提取,加入氯化钠均质,离心分层后取部分乙腈层经溶剂转换后过阳离子交换柱净化,所得净化液经浓缩定容后供气相色谱仪(GC)和气相色谱-质谱仪(GC-MS)分析。气相色谱-质谱法采用选择离子扫描方式(SIM),外标法定量。结果表明,在最优条件下15种三唑类农药的定量下限(S/N≥10)均可达到0.01 mg/kg,在0.01、0.05、0.10 mg/kg三个加标水平下的回收率为68%~102%,相对标准偏差为2.4%~16.2%。实验特别考察了该净化方法在气相色谱-电子捕获检测器(ECD)上的适用性,发现各种蔬菜水果(包括葱属蔬菜)均可获得干扰极少的ECD谱图。方法简单、快速,适用于多种蔬菜水果中15种三唑类农药残留的测定。     

以三唑农药为配体的两个铜配合物的合成、晶体结构与抑菌活性

由三唑农药烯效唑和多效唑合成了2个铜配合物[CuL₄¹Cl₂](1)和[CuL₄²Cl₂·4H₂O](2)(L¹=uniconazole,L²=paclobutrazol)。通过元素分析、红外光谱和X-ray单晶衍射对其结构进行了表征。结构分析表明,1属三斜晶系,P1空间群,晶胞参数为a=0.8956(3)nm,b=1.3267(4)nm,c=1.4918(4)nm,α=94.828(3)°,β=97.774(3)°,γ=105.280(3)°,V=1.6808(9)nm³。2属三斜晶系,P1空间群,晶胞参数为a=1.02189(19)nm,b=1.329(3)nm,c=1.3664(3)nm,α=81.564(2)°,β=79.508(2)°,γ=79.185(2)°,V=1.7853(7)nm³。在2个配合物中,六配位的铜离子都采取扭曲的八面体配位构型,分别来自三唑配体的4个氮原子和2个氯原子配位。1和2都由分子间氢键连接成一维链结构。与相应的配体相比,1和2的抑菌活性明显增强。     

以三唑农药为配体的两个铜配合物的合成、晶体结构与抑菌活性(英文)

由三唑农药烯效唑和多效唑合成了2个铜配合物[CuL14Cl2](1)和[CuL24Cl2·4H2O](2)(L1=uniconazole,L2=paclobutrazol)。通过元素分析、红外光谱和X-ray单晶衍射对其结构进行了表征。结构分析表明,1属三斜晶系,P1空间群,晶胞参数为a=0.895 6(3)nm,b=1.326 7(4)nm,c=1.491 8(4)nm,α=94.828(3)°,β=97.774(3)°,γ=105.280(3)°,V=1.680 8(9)nm3。2属三斜晶系,P1空间群,晶胞参数为a=1.021 89(19)nm,b=1.329(3)nm,c=1.366 4(3)nm,α=81.564(2)°,β=79.508(2)°,γ=79.185(2)°,V=1.785 3(7)nm3。在2个配合物中,六配位的铜离子都采取扭曲的八面体配位构型,分别来自三唑配体的4个氮原子和2个氯原子配位。1和2都由分子间氢键连接成一维链结构。与相应的配体相比,1和2的抑菌活性明显增强。     

识别三唑类农药的片段印迹聚合物的合成及在固相萃取中的应用

采用片段印迹技术, 合成了一系列对7种三唑类农药(三唑酮、烯唑醇、多效唑、烯效唑、戊唑醇、三唑醇和双苯三唑醇)具有识别能力的聚合物. 振荡平衡吸附实验表明, 以邻硝基苯酚为模板的聚合物(M1)对上述7种农药具有最佳的选择性吸附性能. 根据分析物结构对片段印迹聚合物吸附能力的影响, 提出了片段印迹聚合物的识别机理: 三唑类化合物的分子片段末端苯环进入片段印迹聚合物的孔穴中, 同时其羟基与聚合物孔穴外的功能单体4-乙烯基吡啶上的氮原子形成氢键, 二者的协同作用实现对目标分子的选择性识别, 其中分析物末端苯环和聚合物孔穴的匹配是影响片段聚合物识别能力的主要因素. 将基质固相分散(MSPD)与以M1为吸附剂的分子印迹固相萃取(MISPE)联用, 用于土壤样品的前处理. 在3种添加水平下, 各分析物的回收率均为75%~102%, 相对标准偏差为3%~9%(n=5), 方法检出限(信噪比等于3)0.9~15 μg/kg. 表明该分析方法结合了MSPD的快速提取和MISPE的高选择性的特点.     

流动相组成及温度对4种1,2,4-三唑类农药对映体手性拆分的影响

流动相组成及温度对4种1;2;4-三唑类农药对映体手性拆分的影响;纤维素-三(二甲基苯基氨基甲酸酯);手性固定相;HPLC     

Determination of pK(a) of acetic and benzoic acids in pyridine

The pK(a)'s of acetic acid and benzoic acid in pyridine as solvent are found to be 10.1 and 9.8, respectively, at 25 degrees . These results are based on measurements of hydrogen ion activities in mixtures of the acids and their tetrabutylammonium salts. Supplementary studies of differential vapour pressure characteristics of solutions of the acids and the acid-salt mixtures, and conductance of tetrabutylammonium benzoate solutions are also incorporated.     

Influence of Triazole Pesticides on Wine Flavor and Quality Based on Multidimensional Analysis Technology

Triazole pesticides are widely used to control grapevine diseases. In this study, we investigated the impact of three triazole pesticides—triadimefon, tebuconazole, and paclobutrazol—on the concentrations of wine aroma compounds. All three triazole pesticides significantly affected the ester and acid aroma components. Among them, paclobutrazol exhibited the greatest negative influence on the wine aroma quality through its effect on the ester and acid aroma substances, followed by tebuconazole and triadimefon. Qualitative and quantitative analysis by solid-phase micro-extraction gas chromatography coupled with mass spectrometry revealed that the triazole pesticides also changed the flower and fruit flavor component contents of the wines. This was attributed to changes in the yeast fermentation activity caused by the pesticide residues. The study reveals that triazole pesticides negatively impact on the volatile composition of wines with a potential undesirable effect on wine quality, underlining the desirability of stricter control by the food industry over pesticide residues in winemaking.     

反相高效液相色谱法同时测定混合制剂中的甲拌磷与戊唑醇

5.3%甲拌·戊可湿性粉剂是由甲拌磷和戊唑醇加上适当的助剂和辅料复配而成的杀虫、杀菌剂。本文采用反相高效液相色谱法对5.3%甲拌·戊可湿性粉剂中的甲拌磷和戊唑醇进行分离测定。该法稳定、快速,操作简单,分离完全,是一种较为实用的分析方法。1实验部分1.1仪器与试剂HP1100型     

泛昔洛韦解离常数和结合常数的测定

采用紫外分光光度法,在225 nm与305 nm波长处测得泛昔洛韦的解离常数pKa均为3.8.在含有泛昔洛韦的pH值为7.0的Na2HPO4-KH2PO4缓冲溶液中加入牛血清白蛋白,以双倒数公式法测定二者的结合常数.结果表明,牛血清白蛋白与泛昔洛韦形成了1∶4的配合物,其结合常数是4.51×106 L/mol.方法简便,结果可靠。     

两种β-环糊精单臂键合固定相液相色谱法拆分三唑类手性农药

以有序介孔材料SBA-15为基质, β-环糊精和氨基β-环糊精为配体, 通过环糊精端口的羟基和氨基与3-异氰酸丙基三乙氧基硅烷偶联剂上活泼的异氰酸酯基之间的加成反应, 制备了2种不同单键合臂的β-环糊精修饰SBA-15手性固定相(CDSP和NCDSP), 它们分别含有稳定的氨基甲酸酯基和脲基键合臂. 在反相高效液相色谱模式下, 以灭菌唑、 烯唑醇、 己唑醇和戊唑醇等10种常见的三唑类手性农药为探针, 考察了CDSP和NCDSP的基本手性色谱性能. 研究结果表明, 2种新固定相对三唑类农药对映体均有较好的快速拆分能力, 所需分离时间较短(< 30 min), 其中灭菌唑和烯唑醇的选择性因子(α)分别为1.29和1.28, 分离度分别达到3.84和3.23. 采用甲醇、 乙腈和水组成的简单流动相, 室温下在CDSP和NCDSP上分别拆分了9种和8种三唑类手性农药对映体. 研究发现拥有适当大小和手性碳连接羟基的三唑类农药在上述2种新固定相上有较好的拆分效果, 说明固定相上的环糊精配体对溶质的包结、 氢键和空间位阻等协同作用对空间手性识别有重要贡献. 不同批次CDSP和NCDSP的键合量分别为0.139~0.156和0.120~0.137 μmol/m², 表明2种固定相的制备方法有较好的重现性. 与涂覆型纤维素商品柱相比, 新的脲基环糊精固定相性能更稳定, 反相色谱实用性更强, 且制备方法简便, 成本较低, 在三唑类手性农药对映体残留量检测中具有良好的应用前景.     

Determination of pK(a) values of N-heterocyclic bases by fluorescence spectrophotometry

Fluorimetry is a relatively fast and accurate means of determining the dissociation constants of sparingly soluble heterocyclic bases. Complications can arise, however, from the dependence of fluorescence on excited-state as well as ground-state acid-base chemistry. Several approaches to circumventing or compensating for this difficulty are discussed. To demonstrate the utility of the methods, the pK(a), values of the conjugate acids of two bases are evaluated by the methods described.     

Two Years of Pesticides Monitoring in a Belgian Watershed

A monitoring study was carried out in 1998-1999 on a medium-sized (c. 4580 km²) watershed of the Dyle (or Dijle) river in central Belgium, composed of both rural and urbanized areas. This watershed may be considered as representative of a large part of the country. Samples were taken each month from seven sites along the course of the river, plus one from its major affluent the Demer. The eight molecules monitored were the main herbicides used on the major crops in the area, plus some used in nonagricultural sectors. The concentrations found were mostly in the 0-3 μg/L range, with some peaks between 3 and 14 μg/L. The averages over all spring and summer samples analyzed ranged from 0.14 (bentazone) to 1.54 μg/L (diuron). Time and space specific patterns could be observed.     

Simultaneous Determination of Dopamine and Ascorbic Acid at a Triazole Self-Assembled Monolayer-Modified Gold Electrode

A 3-amino-5-mercapto-1,2,4-triazole (TA) self-assembled monolayer-modified gold electrode (TA SAM/Au) is characterized by X-ray photoelectron spectroscopy, A.C. impedance, cyclic voltammetry, chronoamperometry and chronocoulometry. The TA SAM/Au exhibited good promotion of the electrochemical oxidation of dopamine. Some electrochemical parameters of dopamine such as electron transfer number, exchange current density, standard heterogeneous rate constant, diffusion coefficient, etc., were measured by different electrochemical methods. The peak currents of dopamine were linearly dependent on its concentration in the range of 1.5 × 10⁻⁶–1.0 × 10⁻⁴ mol L⁻¹, with a detection limit of 5.0 × 10⁻⁷ mol L⁻¹. The oxidative peak potentials of dopamine and ascorbic acid were well separated at about 190 ± 10 mV in pH 2.0 BR buffers at TA SAM/Au, the oxidation peak current increases approximately linearly with increasing concentration of both dopamine and ascorbic acid in the concentration range of 9.98 × 10⁻⁶–4.54 × 10⁻⁴ mol L⁻¹. It can be used for simultaneous determination of dopamine and ascorbic acid.     

Determination of pK(a) values of diastereomers of phosphinic pseudopeptides by CZE

A CE method was used for the determination of acidity constants (pK(a)) of a series of ten phosphinic pseudopeptides, which varied in number and type of ionogenic groups. Effective electrophoretic mobilities were measured in the 1.8-12.0 pH range in the BGEs of constant ionic strength of 25 mM. Effective electrophoretic mobilities, corrected to standard temperature of 25 degrees C, were subjected to non-linear regression analysis and the obtained apparent pK(a) values were recalculated to thermodynamic pK(a)'s by extrapolation to zero ionic strength according to the extended Debye-Hückel model. The pK(a) values of the phosphinic acid group fell typically in the 1.5-2.25 interval, C-terminal carboxylic groups in the 2.94-3.50 interval, carboxylic groups of the lateral chain of glutamate and aspartate in the 4.68-4.97 interval, imidazolyl moiety of histidine in the 6.55-8.32 interval, N-terminal amino groups in the 7.65-8.28 interval and epsilon-amino group of the lateral chain of lysine in the 10.46-10.61 interval. Further, separation of diastereomers of the phosphinic pseudopeptides was investigated in achiral BGEs. Evaluation of the resolution of the diastereomers as a function of pH of the BGE revealed that most suitable pH region for separation of the diastereomers is around the pK(a) values of the central phosphinic acid group of the pseudopeptides. Successful separation of some diastereomers was, however, achieved in the neutral and alkaline BGEs as well.     

Determination of pK(a)'s for thymol blue in aqueous medium: evidence of dimer formation

Formation constants for recrystallized thymol blue were determined in water, using the SQUAD and SUPERQUAD programs. The best model correlating spectrophotometric, potentiometric and conductimetric data was fitted with the dissociation of HL⁻=L²⁻+H⁺−log K=8.918±0.070 and H₃L₂⁻=2L²⁻+3H⁺−log K=29.806±0.133 with the SUPERQUAD program at variable low ionic strength (1.5×10⁻⁴–3.0×10⁻⁴ M); and HL=L²⁻+H⁺−log K=8.9±0.000, H₃L₂⁻ =2L²⁻+3H⁺−log K=30.730±0.032, H₄L₂=2L²⁻+4H⁺−log K=32.106±0.033 with SQUAD at 1.1 M ionic strength.     

A Novel RP-LC Method for Determination of pK a Values of Some Anticancer Agents and Their Assay

A simple, reliable, and rapid RP-LC method has been developed for the determination of some anticancer drugs (daunorubicin, doxorubicin and vincristine sulfate) in their dosage forms and human urine. These compounds are well separated on a C18 column using the mobile phase consisting of a mixture of acetonitrile (50:50; v/v) at a flow rate of 1.5 mL min⁻¹. The analyte peaks were detected at 235 nm for doxorubicin and daunorubicin, and 220 nm for vincristine. Linearity was obtained in different concentration ranges between 0.10 and 12 μg mL⁻¹ for all compounds. Good sensitivity for all analytes was observed with DAD detection. LOD and LOQ of the method were found satisfying. The proposed method has been extensively validated in accordance with ICH guidelines and obtained results proved that the proposed method was precise, accurate, selective, and sensitive for simultaneous analysis of studied compounds. All analytical procedures including sample preparation, flow rate, and run time were at low levels. Also, pK _a values were determined using the dependence of the retention factor on the pH of the mobile phase. The effect of the mobile phase composition on the ionization constant was studied by measuring the pK _a at different methanol–water mixtures, ranging between 45 and 60 % (v/v).

     

A Novel RP-LC Method for Determination of pK a Values of Some Anticancer Agents and Their Assay

A simple, reliable, and rapid RP-LC method has been developed for the determination of some anticancer drugs (daunorubicin, doxorubicin and vincristine sulfate) in their dosage forms and human urine. These compounds are well separated on a C18 column using the mobile phase consisting of a mixture of acetonitrile (50:50; v/v) at a flow rate of 1.5 mL min^?1. The analyte peaks were detected at 235 nm for doxorubicin and daunorubicin, and 220 nm for vincristine. Linearity was obtained in different concentration ranges between 0.10 and 12 μg mL^?1 for all compounds. Good sensitivity for all analytes was observed with DAD detection. LOD and LOQ of the method were found satisfying. The proposed method has been extensively validated in accordance with ICH guidelines and obtained results proved that the proposed method was precise, accurate, selective, and sensitive for simultaneous analysis of studied compounds. All analytical procedures including sample preparation, flow rate, and run time were at low levels. Also, pK _a values were determined using the dependence of the retention factor on the pH of the mobile phase. The effect of the mobile phase composition on the ionization constant was studied by measuring the pK _a at different methanol–water mixtures, ranging between 45 and 60 % (v/v).