[反]-β-法尼烯类似物的设计、合成与生物活性研究

对[反]-β-法尼烯(EBF)类似物的骨架结构原子进行改造,引入吡虫啉系列活性基团,设计合成了13个结构新颖的EBF类似物,并对其生物活性进行了研究.结果表明,这些化合物对蚜虫具有明显的抑制活性,尤其在低浓度时活性更明显,如质量浓度为25mg/L时,I₁₀和I₁₃对蚜虫的抑制率分别为93.1%和87.1%,远高于同浓度下吡虫啉的抑制率(66.7%).     

新型硝基亚甲基类新烟碱化合物的合成及其杀虫活性

以昆虫乙酰胆碱受体为作用靶标的新烟碱类杀虫剂属于高效、高选择性和环境友好的杀虫剂,依据新烟碱类杀虫剂活性与结构关系,以吡虫啉及其类似物NTN32692为先导结构,在咪唑啉环位置并入可以增强分子脂溶性的六元环基团,设计合成了9个未见文献报道的硝基亚甲基类新烟碱化合物,所有目标化合物的结构均经1H NMR、IR和HR-MS测试技术的确证。初步的生物活性测试结果表明,在500 mg/L下所有目标化合物对豆蚜(Aphis craccivora)都有一定的杀死活性,其中活性最高的化合物4对豆蚜(Aphis craccivora)的校正死亡率为73.0%。并对目标化合物5a～5h的合成方法进行了探讨。     

Synthesis and insecticidal activities of novel bridged-neonicotinoids

A series of novel bridged-neonicotinoid analogues were designed and synthesized, which were constructed by starting material 8 with cyclopentenone or cyclohexenone in the presence of catalyst aluminium chloride. All of the compounds were characterized and confirmed by ¹H NMR, ¹³C NMR, HRMS and IR. The bioassay tests showed that compounds 5 and 6a showed higher bioactivities than imidacloprid against Aphis craccivora.     

Liquid chromatography-mass spectrometry identification of imidacloprid photolysis products

Photolysis of imidacloprid by near ultraviolet (UV) radiation was investigated using reversed phase liquid chromatography (RPLC) and liquid chromatography-electrospray ionization/mass spectrometry (LC-ESI/MS) operated in the positive ion mode. The decomposition of imidacloprid by near UV light is first order with a half life of 10.18 h. Photo-degradation products of imidacloprid identified in this study included imidacloprid urea, imidacloprid olefin, and imidacloprid desnitro. A degradation pathway is proposed for imidacloprid from an examination of the product decay curves obtained in this monitoring study which was performed in a batch test mode.     

Synthesis,insecticidal activity and stability study of novel nitromethylene neonicotinoids with five-membered aromatic heterocycles

Twenty-four novel neonicotinoid analogues with nitromethylene and five-membered aromatic heterocycles were designed and synthesized. All target molecular structures have been confirmed by analytical and spectral data. Some compounds exhibited notable insecticidal activities against aphid (Aphis medicaginis) and brown planthopper (Nilaparvata lugens). The aqueous stability test confirmed that the stabilities of those compounds were superior to the leading compound, and the photostability was even better than that of imidacloprid.     

吡虫啉的酶联免疫吸附分析方法研究

通过碳二亚胺法将吡虫啉交联于牛血清蛋白(BSA)作为免疫抗原,混合酸酐法将吡虫啉交联于卵清蛋白(OVA)作为包被抗原,免疫Balb/c小鼠,采用B细胞杂交瘤技术,经免疫、融合、筛选、克隆,得到抗吡虫啉单克隆抗体,抗体亚类为IgG1,制备的单克隆抗体效价达1×107,确定了吡虫啉酶联免疫吸附分析方法(ELISA)的最佳工作条件,建立了定量测定吡虫啉的间接竞争ELISA方法。本方法的IC50为(15.12±1.28)μg/L,检出限为(1.76±0.02)μg/L。与其它吡虫啉结构类似物无交叉反应。批内相对标准偏差为4.5%;批间相对标准偏差5.1%,饮用水、重庆理工大学地下水和重庆市花溪河地表水平均添加回收率分别为102%,97%和85%。本研究建立了一种快速检测环境水中吡虫啉残留的方法。     

Flow injection analysis of imidacloprid in natural waters and agricultural matrixes by photochemical dissociation, chemical reduction, and nitric oxide chemiluminescence detection

A flow injection analysis (FIA) to quantify imidacloprid was developed based upon (1) ultraviolet (254 nm) photochemical dissociation of imidacloprid to produce nitrite, (2) chemical reduction of the nitrite to nitric oxide by iodide in acid, (3) removal of gas-phase nitric oxide from the aqueous stream using a membrane separator, and (4) detection of the nitric oxide by chemiluminescent reaction with ozone. The cross-reactivity of imidacloprid with eight metabolites of imidacloprid was determined using a commercial ELISA kit and the FIA method. While the ELISA kit demonstrated varying degrees of cross-reactivity, cross-reactivity in the FIA method was observed for only the N-nitro and N-nitroso metabolites. The optimized analytical FIA method, FIA provides a linear response in imidacloprid concentration over four orders of magnitude, has a limit of detection of 5.6 pmol (1.5 ng) of imidacloprid, and exhibits an inter-day precision of 0.4%. Spike-recoveries by FIA demonstrated excellent recovery of imidacloprid in natural waters, hemlock xylem fluid, honey, and grapes with little to no interference from the matrix.     

A liquid chromatography with tandem mass spectrometry method to simultaneously determinate chlorpyrifos,imidacloprid and imidacloprid metabolites in wheat

A liquid chromatography with tandem mass spectrometry method was developed and validated to simultaneously determine chlorpyrifos, imidacloprid, and imidacloprid metabolites in soil, wheat grain, and wheat straw matrices. Satisfactory linearity (R² ≥ 0.9965) of the method was obtained for all analytes. The ranges of limits of detection and limits of quantification for seven analytes in three matrices were 0.17–66.7 and 0.5–200 μg/kg, respectively. Average recoveries were 72.85–81.25% for chlorpyrifos, 78.54–84.70% for imidacloprid, 73.83–81.03% for imidacloprid olefin, 71.47–80.61% for 5‐hydroxy imidacloprid, 71.79–81.32% for imidacloprid urea, 70.42–82.20% for imidacloprid nitroguanidine, and 70.91–82.46% for imidacloprid 6‐chloronicotinic acid in soil, wheat grain, and wheat straw. The intra‐ and interday relative standard deviations were less than 8%. The established method was successfully applied for the residual analysis of chlorpyrifos, imidacloprid, and imidacloprid metabolites in actual soil, wheat grain, and wheat straw samples. The results indicated that the established method could be used to detect trace amounts of chlorpyrifos, imidacloprid, and imidacloprid metabolites in wheat and that the method might be able to provide some data on the detection of these seven compounds in other crops.     

Synthesis and Characterization of Imidacloprid/Hydrotalcite-like Compound Nanohybrids

Hydrotalcite‐like compounds (HTlc) were first modified by sodium dodecyl sulfate (SDS), then the intercalation of imidacloprid (IM) into modified HTlc was carried out in mixed solvent of toluene/ethanol by an evaporating solvent enhanced intercalation method, obtaining IM‐SDS‐HTlc nanohybrids. It was found that the nanohybrids could well control the release of imidacloprid, demonstrating that the nanohybrids are a potential pesticide controlled‐release formulation. The release of imidacloprid from IM‐SDS‐HTlc nanohybrids is dependent on the pH and the presence of electrolyte in release medium. Acidic medium and the presence of electrolytes induce the higher release rate of imidacloprid. The release process of imidacloprid from IM‐SDS‐HTlc nanohybrids can be described by pseudo‐second‐order release kinetics.     

离子交换固相萃取-高效液相色谱法研究吡虫啉在梨中的分布及残留动态

建立一种以固相萃取(SPE)、高效液相色谱(HPLC)为基础的测定梨果皮、果肉中吡虫啉残留量的方法。样品用乙腈进行提取,经二氯甲烷液液分配后用阳离子交换固相萃取(SCX-SPE)柱净化,高效液相色谱/二极管阵列检测法(HPLC/DAD)测定。各种添加水平(果皮:0.05、0.1、0.5、2 mg/kg;果肉:0.05、0.5、1mg/kg)的回收率为83%~103%,相对标准偏差(RSD)小于10%,方法的检出限为0.05 mg/kg。运用此方法分别对梨果皮和果肉中吡虫啉的残留动态进行研究,发现吡虫啉主要在梨果皮中残留,得到吡虫啉在果皮中的消解动态方程为:wt=w0×exp(-0.235t),半衰期是2.98 d。     

液相色谱-串联质谱法测定蜂产品中吡虫啉及其3种代谢物

建立了蜂蜜和蜂花粉中吡虫啉及其代谢物吡虫啉烯烃、吡虫啉脲、6-氯烟酸的液相色谱-串联质谱(LC-MS/MS)检测方法.在QuEChERS方法基础上,针对目标物化学性质和样品杂质情况,对提取溶液的pH值、提取次数、净化材料等参数进行了优化.最终以5％甲酸-乙腈溶液提取两次,无水MgSO4、NaCl盐析分层,提取液经增强型脂类去除材料(EMR)净化,以LC-MS/MS进行测定,基质外标法进行定量分析.结果表明,蜂蜜和蜂花粉中吡虫啉、吡虫啉烯烃、吡虫啉脲、6-氯烟酸的平均加标回收率为86.0％～111.5％, 相对标准偏差在1.7％～9.6％之间, 检出限分别为0.20, 3.50, 0.40和14.00 μg/kg,定量限分别为0.60, 11.64, 1.20和45.00 μg/kg.本方法分析速度快、灵敏度高、重现性好,适用于蜂蜜和蜂花粉中吡虫啉及其3种代谢物的快速测定.     

高效液相色谱法测定吡虫啉和哒螨灵

 用高效液相色谱法测定二元混配吡哒可湿性粉剂中的吡虫啉和哒螨灵的质量分数。色谱柱为 μBondapakC1 8柱 (3 .9mm i.d.× 3 0 0 mm) ,流动相为乙腈 -甲醇 -水 (体积比为 60∶ 1 0∶ 3 0 ) ,用二极管阵列检测器 ,检测波长为 2 40 nm,可得到满意的分离效果。     

Determination of Imidacloprid Based on the Development of a Glassy Carbon Electrode Modified with Reduced Graphene Oxide and Manganese (II) Phthalocyanine

An electrochemical sensor of glassy carbon electrode modified with reduced graphene oxide and manganese (II) phthalocyanine (GCE/rGO/MnPc) was developed as an effective alternative in the determination of imidacloprid in honey samples. The peak current variation obtained with the proposed sensor, in the presence of imidacloprid, was higher compared to the bare GCE. The followed experimental conditions were optimized: reduced graphene oxide concentration (2.0 mg mL^?1), manganese (II) phthalocyanine concentration (1.5 mg mL^?1), electrolyte pH (6.5) and electrolyte concentration (1,50 mol L^?1). The study also showed that the process of reduction of imidacloprid is irreversible and diffusion‐controlled, with a single reduction peak of approximately ?0.9 V corresponding to the reduction of the nitro group (?NO2) present in the structure, generating a derived from hydroxylamine, in a process involving about four electrons. The determination of imidacloprid in honey samples exhibited recovery values within the EPA range (between 90.5 and 101.9 %). The proposed sensor GCE/rGO/MnPc can be used as an effective alternative in the determination of imidacloprid in honey samples.     

Synthesis and Biological Activity Evaluation of Novel <em>β</em>-Substituted Nitromethylene Neonicotinoid Analogues

The structure-based design and synthesis of a series of novel neonicotinoid analogues are described. The novel neonicotinoid analogues were designed based upon the reaction of enamine derivatives with electron-withdrawing β-substituents with electrophilic thiocyanogen reagents. These compounds were characterized by spectroscopic methods. Bioassays indicated that some of the synthesized compounds exhibited excellent bioactivity against cowpea aphids (Aphis craccivora). The LC₅₀ values of compounds 7, 9, 12, 13, 15, 17, 19, 20 and commercial imidacloprid were 0.01567, 0.00974, 0.02494, 0.01893, 0.02677, 0.01778, 0.0220, 0.02447 and 0.03502 mmol L^-1, respectively, which suggested that they could be used as leads for future development of new insecticides.     

Absorption,transportation and distribution of imidacloprid in maize

The neonicotinoid imidacloprid is a very important insecticide in maize cultivation in China. A laboratory experiment was conducted to investigate its absorption, transportation and distribution in maize plants. Plants were exposed to an aqueous solution of imidacloprid at five concentrations (10, 20, 50, 100 and 200 μg/mL). The residues of imidacloprid in different plant parts were determined by using a quick and effective method of high-performance liquid chromatography. Results showed that the average recoveries ranged from 85.16% to 102.23%, with relative standard deviations of 1.82–4.40% at three different spiking levels in each different matrix. The half-lives of imidacloprid in hydroponic maize water were from 5.33 to 11.55 days. The concentrations in roots, stems and leaves were from 5.61 to 7.48, 1.03 to 4.03 and 0 to 30.57 μg/mL after 6 h–7 days exposed in 10 μg/mL imidacloprid aqueous solutions, respectively. Our study showed that imidacloprid was strongly absorbed by roots and mainly accumulated in leaves. Quantity ratio and bioconcentration factors (BCFs) were also used to estimate the distribution and accumulation in maize. The values of quantity ratios were the highest in the leaves while lowest in the root after 7 days treatments, with the ranking of leaves > stem > root. The BCFs were 0.63–1.66, 0.52–0.92 and 3.20–6.78 in root, stem and leaves, respectively. These results demonstrated that the exposed time and imidacloprid application concentrations were also the main factors influencing the absorption. This study enhances our understandings of the uptake and distribution of imidacloprid in maize plants.     

Biodegradation of imidacloprid in sandy loam soil by Bacillus aerophilus

A study of the biodegradation of imidacloprid in soil was carried out under laboratory conditions. Sandy soil samples were fortified with imidacloprid at 50, 100 and 150 mg kg^?1 along with 45 x 10⁷ colony forming units (cfus) of Bacillus aerophilus and the samples were compared with unamended soil. The samples were extracted with acetonitrile, cleaned up by treatment with primary secondary amine sorbent and graphitised carbon black. The residues of imidacloprid and its metabolites were analysed by high performance liquid chromatography. The parent compound, imidacloprid, was found to be more persistent in both the treatments. Among metabolites, the highest values were obtained for urea and olefin while 5-hydroxy, 6-chloronicotinic acid (6-CNA), nitrosimine and nitroguanidine (NTG) were also observed in all the treatments in amended soil. In case of unamended (control) soil, 6-CNA was found to be the most persistent metabolite followed by olefin, urea, 5-hydroxy, nitrosimine and NTG metabolites. Total imidacloprid residues for control soil samples followed first-order kinetics at 50 and 150 mg kg^?1 but in case of control imidacloprid fortified at 100 mg kg^?1, the total residues of imidacloprid and its metabolites followed pseudo-first-order kinetics. The respective half-life value for 50 mg kg^?1 was 25.08 days and 30.10 days for both 100 and 150 mg kg^?1. However, total imidacloprid residues followed pseudo-first-order kinetics for its applications at 50, 100 and 150 mg kg^?1 in sandy loam soil amended with B. aerophilus. The half-life values for 50, 100 and 150 mg kg^?1 were worked out to be 14.33, 15.05 and 18.81 days, respectively. With the use of B. aerophilus, the reduction percentage of initial applied dose imidacloprid in sandy loam soil was found to be higher in all the three doses as compared to that of the control samples.     

Development of extraction procedures for the determination of imidacloprid: application to residue analysis and dynamics of two formulations in Chinese cabbage

This study was undertaken to investigate whether an additional column clean-up procedure can affect the accuracy of an analytical method developed for the determination of imidacloprid residues in Chinese cabbage. Thereafter, the residue levels and the degradation rates of imidacloprid were investigated in experimental Chinese cabbage plots after treatment with two different commercial formulations: emulsifiable concentrate (EC) and wettable powder (WP). The analyte was determined using high-performance liquid chromatography-ultraviolet detection (HPLC-UVD) and confirmed by high-performance liquid chromatography-mass spectrometry (HPLC-MS) in the select ion-monitoring mode. The mean recoveries ranged from 75.34 to 98.00% and 96.95 to 100.97%, with relative standard deviations of 0.86-4.14 and 1.22-3.52%, in samples treated with and without additional column clean-up procedures, respectively. The minimum detectable amount of imidacloprid was 4 ng, while the limits of detection and quantitation were 0.2 and 0.5 ppm, respectively. The degradation of pesticide was monitored throughout a period of 13 days under greenhouse conditions. Although the behaviors of the EC and WP formulations appear to be similar, the absolute residue levels obtained with EC and WP treatments differed slightly. When imidacloprid formulations were applied (as foliar treatments) according to the recommended rate, the final residues (13 days post-treatment) in Chinese cabbage were much lower than the maximum residue limit (MRL = 3.5 ppm) established by the Korean Food and Drug Administration. Taken together, our study suggests that the analysis of imidacloprid can be performed without an additional column clean-up procedure, and the decline curve and the residue levels in Chinese cabbage could change if the same active ingredient is used in different formulations.     

Determination of the Insecticide Imidacloprid in Potato (<Emphasis Type="Italic">Solanum tuberosum</Emphasis> L.) and Onion (<Emphasis Type="Italic">Allium cepa</Emphasis>) by High-Performance Liquid Chromatography with Diode-Array Detection

A high-performance liquid chromatography (HPLC) method has been proposed for the determination of imidacloprid residues in fortified potato (Solanum tuberosum L.) and onion (Allium cepa) and in treated potato and onion samples. Sample preparation consisted of dichloromethane extraction of imidacloprid from the plant material, followed by purification of the obtained onion extract on an LC-Florisil disposable cartridge. The obtained potato extracts were further analyzed without purification. The HPLC-diode-array-detection (DAD) method has been developed on reversed phase for separation of imidacloprid with isocratic elution with a mixture of 0.01 M phosphate buffer (pH 3.15) and acetonitrile (75 : 25, v/v). Spectral data obtained with DAD allow the identification of imidacloprid residue. Detector response showed a linear dynamic range from 0.0125 to 0.500 μg/mL. Imidacloprid was recovered from fortified samples in a range of 94–99%. The within-day RSD of repeatability of the retention time of imidacloprid standard solution was less than 0.1% and of the obtained peak area less than 5%. For potato and onion samples, the limits of detection were 0.0075 and 0.0060 mg/kg and the limits of determination were 0.015 and 0.012 mg/kg, respectively. __________ From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 12, 2005, pp. 1273–1278. Original English Text Copyright ? 2005 by Mandic, Lazic, Okresz, Gaal. The text was submitted by the authors in English.     

Degradation of the insecticides thiamethoxam and imidacloprid by zero-valent metals exposed to ultrasonic irradiation in water medium: electrospray ionization mass spectrometry monitoring

The degradation of thiamethoxam (1) and imidacloprid (2), prototype neonicotinoid insecticides bearing a characteristic N-NO2 moiety in their structures, promoted by a number of zero-valent metals (Fe, Sn, Zn) upon ultrasonic irradiation in acidic aqueous solution (pH 2) was investigated. It was verified that thiamethoxam (1) and imidacloprid (2) are quickly and almost completely consumed under these experimental conditions (degradation >90% after a reaction time of 30 min) and that ultrasonic irradiation strongly enhances the degradation rate for both insecticides, especially when zinc and tin are employed. Based on the results from electrospray ionization mass (and tandem mass) spectrometry in the positive ion mode, degradation routes for both insecticides, comprising an initial NO2 --> NH2 reduction, were proposed. In addition, products from the dehydrochlorination of imidacloprid were also found to be formed under these conditions.     

吡虫啉与牛血红蛋白相互作用的光谱研究

利用紫外可见光谱和荧光光谱研究了在生理pH值条件下农药吡虫啉与牛血红蛋白(BHb)的相互作用。实验结果表明:吡虫啉分子与BHb发生反应生成复合物,导致BHb内源荧光的猝灭,该猝灭属于静态猝灭。测定了不同温度下该反应的表观结合常数、结合位点数及结合热力学参数,热力学参数的变化表明上述作用过程是一个熵增加、自由能降低的自发分子间作用过程,吡虫啉与BHb之间以静电和疏水作用力为主;并用同步荧光光谱法探讨了吡虫啉对BHb构象的影响。