【作者】 张存政；

【导师】 吴益东； 刘贤进；

【作者基本信息】 南京农业大学 ， 农业昆虫与害虫防治， 2011， 博士

【摘要】 虽然农药对于保障作物的产量具有重要的作用,但农药的安全性问题(环境生态安全及人类健康安全)日益受到人们的关注。H9201是我国南开大学元素有机化学研究所国家重点实验室研发的具有自主知识产权的农用化学品,是少数具有广谱除草活性、水旱田两用的新型有机磷类化合物。作为一种新型除草剂,急需建立其残留分析方法,研究其环境释放后的残留行为,评价其环境友好性及安全性,协助设立最大残留限量值(MRL),以利于评估新型除草剂H9201残留对消费者的身体健康构成威胁的风险。1.H9201残留分析ELISA方法的建立以三氯硫磷与2,4-二甲基-6-硝基苯酚为原料,合成了带有氨基的O-甲氧基-O-(2,4-二甲基-6-硝基苯氧基)硫代磷酰胺的人工半抗原,并利用琥珀酸酐法对氨基进行改造,合成连接有4碳臂的羧基基团；利用二甲基吡啶(DMAP)催化活性酯法(NHS)使半抗原与载体蛋白进行偶联,紫外扫描和SDS-聚丙烯酰胺凝胶电泳的结果表明已成功合成了免疫和包被所需的人工抗原。人工抗原的偶联比因载体蛋白的不同而有所不同,Hapten-BSA为42.7:1, Hapten-OVA为18.3：1。以Hapten-BSA作为免疫原对3只新西兰大白兔免疫注射,获得了抗H9201的特异性抗体,成功地建立了基于多克隆抗体的H9201酶联免疫检测技术。所得血清效价分别为：1/51,200(血清H1600),1/56,000(血清H6000),1/102,400(血清H6600)。经方阵滴定和间接非竞争ELISA确定了血清H1600,H6000和H6600的ELISA工作浓度：包被原稀释度为1/256(Hapten-OVA,4.6μg/mL),血清稀释度为1/6400；抗血清H6000的ELISA的工作浓度：包被原为1/256(Hapten-OVA,4.6μg/mL),血清为1／10,000；抗血清H6600的ELISA工作浓度为：包被原为1/512 (2.3μg/mL),血清为1/18,000。分别为3种血清建立了ELISA检测方法：用血清H1600建立的IC-ELISA,对H9201的抑制中浓度(IC50)为5.8551μg/mL,最低检测浓度为0.2291μg/mL,检测范围为0.6508-38.1422μg/mL;用血清H6000建立的IC-ELISA,对H9201的抑制中浓度(IC50)为3.2765μg/mL,最低检测浓度为0.2007μg/mL;用血清H6600建立的IC-ELISA,对H9201的抑制中浓度(IC50)为1.331μg/mL,最低检测浓度为0.017μg/mL,检测范围为0.0524-20.4135μg/mL。以血清H6600建立的H9201的IC-ELISA分析方法可特异性识别其母体化合物,该抗体对结构类似化合物2,4-二甲基-6-硝基苯酚、硝基苯酚、甲胺磷、甲拌磷、毒死蜱、对硫磷均未有识别作用,微弱识别S-羧乙基-O,O-二甲基二硫代磷酸酯、乐果、马拉硫磷,对半抗原及其结构类似物具有高的识别作用。对田间水样、土壤、胡萝卜、添加样本进行检测,回收率因前处理方法的采用与否而不同,在0.05-5.0mg/Kg的添加浓度范围,回收率范围分别为78.4±2.4%-95.2±3.2%,72.1±4.8%-85.4±5.1%和74.4±4.3%-91.3±4-2%。2.H9201残留分析的GC、GC/MS、LC/MS检测方法的建立气相色谱法.硫磷检测器(GC/FPD).在优化的气相色谱条件下建立了H9201在水、土壤、植株中的残留检测方法：DB.17毛细管柱(30m×0.53 mm,0.25μm);程序升温：初始柱温箱温度为150℃,保持2 min,以8℃／min升温到250℃,保持12 min；进样口温度：220℃；检测器(FPD)温度：200℃；载气：高纯氮气,60 mL／min；氢气：75 mL／min；空气：100 mL／min,尾吹：40 mL／min；进样：不分流进样,进样量：1μL,出峰保留时间为13.75min。在添加范围为0.05.1.0 mg/kg,方法的回收率分别为：土壤中90.8-98.4%,胡萝卜中89.2-101.8%,水中97.43-100.91%,田水96.37-115.39%。方法的最低检测限分别为：0.01,0.02,0.008,0.02mg/kg。气相色谱-质谱法(GC/MS).在气相色谱-质谱法分析方法中,气相色谱部分同上,其中质谱部分的检测条件如下：离子电压为70 eV,离子扫描区间20-450 m/z,离子源温度230℃,GC-MS连接部温度280℃,采用SIM模式进行定量与定性分析,目标离子：318.3,定量离子为272(100,),定性离子为230(32),152(22),定量离子为272(100),氦气作为载气,流量为1.0ml/min,保留时间为11.77 min,在添加范围为0.01-1.0mg/kg,方法的回收率为：胡萝卜98.2±4.5-100.8±5.0%,土壤99.8±3.5-96.8±3.5%,田水98.6±5.4-100.3±5.5%,方法的最低检测限分别为：0.008,0.005,0.005 mg/kg。液相色谱-质谱法(LC/IT/MS).液相色谱部分的优化条件为：C18柱(ZORBAX Eclipse 4.6 x 150 mm,3.5μm, Agilent, USA),流动相为80%的乙腈(含0.1%甲酸),20%水(含0.1%甲酸),流量为0.3ml/min。质谱部分的检测条件为：离子阱6300(Agilent, Palo Alto, CA, USA)负离子模式,MRM模式进行定量与定性分析。以23.02mg/L的标准品溶液进行质谱条件优化,出峰保留时间为13.6min,离子317/317,317/248.6,317/165.7及丰度比进行定性定量,吹扫气350℃,流量9 L/min,雾化气压60psi,挥发温度400℃,毛细管电压1200V,在添加范围为0.01-1.0mg/kg,方法的回收率为：胡萝卜89.2±6.8-102.4±4.5%,土壤85.5±3.5-105.4±7.5%,田水92.5±5.4-100.8±6.0%,方法的最低检测限分别为：0.009,0.009,0.007 mg/kg。3.H9201残留的环境行为研究在不同水体中的水解动态。H9201在不同pH值的水体中的稳定性不同,在pH=7的水溶液中较为稳定,水解规律符合伪一级动力学方程,112天后水解开始进行,半衰期为538.29天。在酸性与碱性的条件下降解较快,水解规律符合一级动力学方程,在pH=5水溶液中的半衰期为276.27天,在pH=9水溶液中的半衰期为224.67天,在田间水体中的降解快于其它三种水体,水解规律符合一级动力学方程,半衰期为197.16天,田水中有机质的含量及生物因素的影响可能是加速其在水中降解的原因。H9201在水中的主要初级水解产物为O-甲基-O-(2,4-二甲基-6-硝基)-N-羟基硫代磷酰胺酯,同时描绘出可能的光解与水解过程。在土壤中的残留消解动态。H9201在土壤中的残留动态数据,经不同的模型模拟分析,及不同的统计软件(Microsoft Excel Solver,GraphPad Prism 5.0,)统计分析,发现H9201在土壤中的残留动态同时满足一级动力学方程、一级不连续二期方程和一期指数衰减方程、二期指数衰减方程,经分析表明最为真实反应H9201在土壤中衰减动态为一级不连续二期方程,C=7.0264e-0.0700t1+1.1396e-0.0120t2,其在土壤中的半衰期为9.9天。H9201在收获后的植株(胡萝卜)、土壤中的残留水平。试验分析表明收获后的植株(胡萝卜)中的H9201的残留应来源于环境施用后的残留,预示此药剂在植株体内可能具有累积性,且在水溶液环境中较为稳定存在,因而对水生环境生物的负作用应进行深入研究。在胡萝卜、土壤中的残留量分别小于0.02,0.4mg/kg。更多还原

【Abstract】 Agrochemicals play important roles in modern agriculture; however, concerns about environmental impact of agrochemical and risk to human health have increased. Due to the intellectual property rights, research aiming at the development of enviromental friendly and safely agri-chemicals is increasingly important. H9201 is a new agent for the weed control, which was invented by the State Key Lab of Element-organic Chemistry (Nankai University), and performed broad-spectrum weed control activity under water field and dry field conditions. Hereby, our study focused on the analytical method development and enviromental fate analysis and dissipation pathway profiling of this new agent in order to provide basic information for the evaluation of risk to human health, which will help to determine the maxiam residue limit value (MRL). Our research conducted includes method development (polycolonal antibody development for the ELISA method establishment, GC, GC/MS, and LC/ESI/ITMS analytical method development), and residual dynamics of H9201 in environment after field application. The main results are listed as follows.1. Indirect competitive enzyme-linked immunosorbent assay (IC-ELISA) development.An indirect competitive enzyme-linked immunosorbent assay (IC-ELISA) for H9201 determination was developed based on polyclonal antibody, and was employed in the sample analysis.Chemical O-methyl-O-(2,4-dimethyl-6-nitrophenoxy)-N-phosphoramide (hapten) was synthesized by thiophosphoryl chloride and 2,4-dimethyl-6-nitrophenol, then succinic anhydride was used to modify amino group with Dimethylamino pyridine (DMAP) catalysising, thereafter conjugated with the carrier proteins bovine serum albumin (BSA) and ovalbumin (OVA) by active ester method (AEM). Final conjugation identified by UV screen and SDS-PAGE, the conjugate ratio of Hapten-BSA is:42.7:1; Hapten-OVA is:18.2:1, respectively. Polyclonal antibodies raised against Hapten-BSA were screened and selected for the IC-ELISA. One set of serum from the rabbit H1600 showed an I50 value of 5.8551μg/mL with a detection limit of 0.2291μg/mL at the concentration of H9201 ranged from 0.6508-38.1422μg/mL, and the serum raised from the rabbit H6000 had an I50 value of 3.2765μg/mL with a detection limit of 0.2007μg/mL at the range of H9201 concentration from 0.3204 to 18.0652μg/mL. A sensitive indirect enzyme-linked immunosorbent assay (ELISA) was developed for the detection of new herbicide H-9201 based on the polyclonal antibody H6600 generated in rabbits by immunizing with synthesized hapten. For standard,50% reduction of the maximum ELISA signal (IC50) was 1.331μg/mL, whereas the detection limit was 0.017μg/mL in the competitive standard curve ranged from 0.05μg/mL to 20.0μg/mL, which combination of the concentrations of coating solution and primary antibody was optimized to 1/512 and 1/18 000, respectively. No significant cross-reactivity for related compounds was observed, such as DMNT, p-nitrophenol, Methamidophos, Phorate, Chlorpyrifos, Parathion, the antibody showed negligible cross-reactivity with S-Carboxylethyl-O,O-Dimethyl-phosphorodithioate, dimethoate, malathion, but high cross-reactivity with analogs of hapten. Recovery of H-9201 in environmental water,soil and carrot based on the developed IC-ELISA method with sample previous treatment step was 78.4±2.4%～95.2±3.2%,72.1±4.8%～85.4±5.1%,74.4±4.3%～91.3±4.2%,respectively.2. Method development of GC, GC/MS, LC/MS for H9201 residue determination.Method Development based on Gas Chromatergraphy with frame photometric detector (FPD). DB-17 (1μm film thickness,30 m length,0.53 mm ID, J&W Scientific, USA) column was used for the analyte analysis, GC work conditions as follows:the inlet temperature was 250℃and the injection was carried out in splitless modle using a 1μL injection volume. For FPD, the detector temperature was 200℃, the initial oven temperature was 150℃, and was maintained for 2 min, the temperature was then increased 8℃/min to 250℃and held for 12 min.The recoveries ranged from 90.8～98.4% in soil matrix,89.2～101.8% in carrot matrix,97.43～100.91% in water,96.37～115.39% in natural pond water, respectively.The limit of detection of method is 0.01 mg/kg in soil,0.02 mg/kg in carrot, and 0.008 mg/kg in tap water,0.02 mg/kg in natural pond water, respectively.HP-5MS (0.25μm film thickness,30 m length,0.32 mm ID, J&W Scientific, USA) connected with MS for GC-MS method development. The gas chromatograph settings were the same as described above. The ionization potential of mass selective detector was 70 eV and the scan range was 20-450 m/z, the ion-source temperature 230℃, and the GC-MS interface temperature 280℃. Selected ion monitoring was performed with target ion 318.3, one quantifying ion 272(100), and two qualifying ions 230 (32),152(22) for analysis, Helium was used as the carrier gas at a flow rate of 1.0 mL·min-1. All gases were Ultra-pure. This analytical procedure gave recoveries of 99.8±3.5～96.8±3.5% in soil and 98.2±4.5～100.8±5.0% in carrot,98.6±5.4～100.3±5.5% in natural pond water for a range of spiked H-9201 concentrations from 0.01 to 1.0 mg/kg.The analytical detection limit in soil, carrot, natural pond water was 0.005,0.008 and 0.005 mg/kg, respectively.LC/IT/MS method development. Detection was performed with an Agilent 1200 MSD ion-trap 6300 system (Agilent, Palo Alto, CA, USA) operating in the electrospray negative mode. The optimized conditions were as followings:nebulizer gas pressure 60 psi, drying nitrogen gas temperature 350℃, drying nitrogen gas flow 9 L/min, vaporizer temperature 400℃, capillary voltage 1200V, the optimized perimeters were obtained with 23.02 mg/L H9201 standard in methanol, and quantization was monitored as [M-H]-ion. The LC-MS mobile phase consisted of 80% phase A (containing acetonitrile and 0.1% formic acid) and 20% Phase B solvent (containing Deion water and 0.1% formic acid) at flow rate of 0.3ml/min.MRM transitions were selected based upon analysis of pure reference standards. The average abundance ratios between the precursors:product ion transitions were determined,317/317 was compared with 317/248.6 and 317/165.7 to ensure the ratios obtained from the plasma standards can be applied to real cases. The recoveries of 89.2±6.8～102.4±4.5% in carrot and 85.5±3.5～105.4±7.5% in soil, 92.5±5.4～100.8±6.0% in natural pond water were archived at the spiked H-9201 concentrations from 0.01 to 1.0 mg/kg.The analytical detection limit in soil, carrot, natural pond water was 0.009,0.009 and 0.007 mg/kg, respectively.3. Dissipation of H9201 in carrot, soil and water after application under field condition.Hydrolysis study of H9201 in different pH water solution. The results of the hydrolysis experiments indicate that hydrolysis of H-9201 started during the 112 days of incubation at pH 7, after this period hydrolysis of H-9201 slowed down, which can be described by modified first-order equation also known as pseudo first-order equation, the half-life was 538.29 days. Dissipation followed the first-order kinetic equation at pH 5 and pH 9, and the hydrolysis rate at pH 9 was faster than at pH 5. The inorganic contents of the natural pond water or biological effects may accelerate the degradation and shorten the half-life, which was 197.2 days. An initial metabolite was found and identified as O-methyl-O-(2,4-dimethyl-6- nitrophenoxy)-N-hydroxy phosphoramide, the most likely pathway of H-9201 hydrolysis is outlined.Dissipation study of H9201 in soil. The results showed that the representation of herbicide persistence by the first-order discontinuous biphasic model was better than simple first-order kinetics and one, two phase exponential decay model, which derived from Microsoft Excel Solver and GraphPad Prism 5.0, and the degradation of H-9201 slowed down from around 30 days after application. The first-order discontinuous biphasic model had a DT50=9.9 days, the best-fit model for H-9201 was finally found to be the first-order biphasic model, and the endpoints derived from this model were accepted for assessment the fate of H-9201, the equation is C=7.0264e-0.0700t1+ 1.1396e-0.0120t2H-9201 residue in post-harvest carrot and in soil. The residue of H-9201 in harvested carrots only came from the environment where the herbicide had been applied before seedling emergence, implying that the residue probably accumulated in carrot via water delivery, since this chemical can persist in the aqueous layer as shown by our hydrolysis study, therefore an environmental impact assessment is needed to determine the bioaccumulation of H-9201 residues in the aqueous environment. The residues of H-9201 present in carrot and soil after application (harvest at 144 days) were less than 0.02 mg/kg in carrot, and less than 0.4 mg/kg in soil.更多还原