【作者】 王瑞婷；

【导师】 王富华；

【作者基本信息】 华中农业大学 ， 植物营养学， 2010， 硕士

【摘要】 汞是自然界中毒性最大的元素之一,应用极广,易挥发,对人体危害很大。不同形态汞化合物毒性差异较大,用总汞评价汞环境危害程度不能准确反映出各形态汞生物毒性的差异性,因此应该对汞的各种形态进行定性定量分析。本研究选择环境中最常见三种汞形态(包括Hg(Ⅱ)、MeHg和EtHg)作为研究对象,首次建立了HPLC-VG-AFS法测定蔬菜中不同形态汞的方法,结果表明：1浊点萃取和漩涡混合提取两种前处理方法相比,漩涡混合操作简便且具有更高的提取效率。2仪器条件优化,包括三个方面：(1)分离条件的优化：以5%乙腈(HPLC级, v/v)-0.462%乙酸铵(m/v)-0.12%L-半胱氨酸(m/v)作为流动相,流速1.0mL/min,选择C18反相硅胶色谱柱(Venusil MP C18,4.6mm×150mm,5μm)为分离柱,各形态汞得到最好的分离,且峰型对称。(2)气体发生条件的优化：氧化剂浓度为1.0%K2S2O8(m/v)+0.5% KOH (m/v),还原剂：1.5%KBH4(m/v)+0.5% KOH(m/v),载流HCl浓度为7%(v/v),在线紫外消解(UV)时信噪比达到最佳。(3)检测条件的优化：汞空心阴极灯灯电流为30 mA,光电倍增管负高压为310 V,原子化器温度为200℃,高度为10 mm,载气流速为400 mL/min,屏蔽气流速为600 mL/min时信噪比达到最佳。3方法评价测定三种形态汞检出限为Hg(Ⅱ)0.14μg/L、MeHg 0.05μg/L、EtHg0.12μg/L,方法加标回收率在75%-110%之间,用10μg/L(以Hg计)的汞形态标准溶液,连续进样7次,其保留时间和峰面积的相对标准偏差分别为：Hg(Ⅱ)3.43%、2.75%, MeHg2.24%、4.07%, EtHg1.38%、3.28%;对同一蔬菜样品菠菜的7次测定结果进行分析,三种形态汞的测定值相对标准偏差分别为Hg(Ⅱ)2.26%,MeHg2.23%, EtHg3.06%,以上各相对标准偏差控制在5%以内。三种形态汞的峰面积和其浓度呈现良好的线性关系,相关系数均大于0.999。4方法应用(1)方法在蔬菜检测中的应用：通过对市场上常见的陆生蔬菜和水生蔬菜进行检测得出：陆地蔬菜基本不存在汞污染,只有个别样品有检出,而且样品中汞形态以无机汞为主,其次为甲基汞,乙基汞均未检出,水生蔬菜中汞含量较高,其形态为无机汞。(2)方法在大米、中药材和水产品检测中的应用：将提取剂中HCl浓度变为10%,其他条件不变。结果表明,大米中汞以甲基汞为主,其次为无机汞,没有乙基汞检出；中药材中没有汞形态物质检出；水产品中汞仅以甲基汞形式存在。更多还原

【Abstract】 Mercury was one of the most toxic elements that were present naturally in the environment. It was widely used in our daily life. Mercury was easy to volatilize and it was harmful to human body. It was well known that the toxicity, biogeochemical behavior and transportation of mercury in the environment were heavily dependent on its chemical form. Total mercury did not convey well the real long-term pollution. so, it was essential to analyze mercury speciations qualitily and quantitatively. In this paper, we established a determination method of ultra-trace amount Hg(Ⅱ), MeHg and EtHg in products by HPLC-VG-AFS for the first time. The main results showed as follows.1 Compared with cloud-point extraction, whirlpool-mix extraction had the advantage of simple operation and higher extraction rate, was regard as the better pretreatment method.2 Optimize the equipment conditions, this part include there aspects:(1) Optimization of the separation condition.5% Acetonitrile (HPLC grade, v/v)-0.462% ammonium acetate (m/v)-0.12% L-Cys (m/v) was chose as mobile phase, flow rate 1.0 mL/min. The mercury compounds were separated on a C18 reverse phase column (Venusil MP C18,4.6mm×150mm,5μm). The there mercury species were baseline separated, and their peaks were all symmetrica.(2) Optimization of VG.1.0% K2S2O8 (m/v)+0.5% KOH (m/v) had been employed for oxidation, reducing agent was 1.5% KBH4 (m/v)+0.5% KOH (m/v), carrier solution was 7% HCl(v/v)and coupled with on-line UV, under these condition conveyed best S/N.(3) Optimization of detection system. The best conditions included that:the negative high voltage of photomultiplier tube was 310 V, lamp current was 30 mA, atomization’s temperature was 200℃, atomization’s hight was 10mm, carrier gas’s flow rate was 400 mL/min, make up gas’s flow rate was 600 mL/min.3 Method evaluation.Under the optimized conditions, the determination limits (D.L.) of Hg(Ⅱ), MeHg and EtHg were found as 0.14,0.05 and 0.12μg/L(as Hg), respectively. The relative standard deviations(R.S.D, 10μg/L, n=7) of Hg(Ⅱ), MeHg and EtHg were 3.43%/ 2.75%,2.24%/4.07% and 1.38%/3.28%(retention time/peak aera), respectively. The Seven relative standard deviations(R.S.D, n=7) of Hg(Ⅱ), MeHg and EtHg was 2.26%,2.23% and 3.06%, respectively. The spike-recovery is between 75%-110%,and a linear dynamic range between 0～10μg/L injected. 4 Method application.(1) Application in vegetable determination. The optimized method had been applied to the quantitative determination of mercury species in terrestrial vegetables and aquatic vegetables. It was showed that:among all the terrestrial vegetables we detected, only foliaceous vegetables contained with Hg(Ⅱ), then MeHg, EtHg was not detected. Mercury concentration was higher in aquatic vegetables, which only contained with Hg(Ⅱ).(2) Application in rice, Chinese herbal medicine and aquatic product determination. Change the concentration of HCl as 10% in extraction solution, other conditions was fixed. It was showed that, MeHg was the main speciation in rice, then Hg(Ⅱ), no EtHg was detected. There was no detectable mercury in Chinese medicinal materials. Mercury speciation in aquatic product was MeHg.更多还原