体积排阻高效液相色谱-电感耦合等离子体质谱测定印度芥菜中镉的形态

Speciation Analysis of Cadmium in Indian Mustard(Brassica Juncea)by Size Exclusion Chromatography-High Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry

建立了体积排阻高效液相色谱-电感耦合等离子体质谱法(SEC-HPLC-ICP-MS)测定镉超积累植物印度芥菜中镉的形态分析方法。在镉胁迫下,诱导产生植物螯合肽(PCs)。因此,在叶片和根部均检测到植物螯合肽(PC)3-Cd、植物螯合肽(PC)2-Cd、谷胱甘肽(GSH)-Cd,及半胱胺酸(Cys)-Cd4种形态。研究结果证明,植物螯合肽的合成机制为先形成GSH-Cd而后形成植物螯合肽。在植物不同部位,Cd存在形态不同。叶片中主要以GSH-Cd存在,而在根部主要以PC2-Cd为主,结合不同镉刺激浓度条件下植物体内镉分布规律初步推断:根部PC2-Cd除了自身合成产生外,还有部分为叶部转移。为了防止巯基化合物氧化反应的发生,样品采取液氮保护并于-70℃保存,样品分析全流程用氮吹防氧化措施。

The method based on the coupling of size-exclusion HPLC with ICP-MS was used for the speciation analysis of cadmium binding non-protein thiols in extracts of Indian mustard（Brassica Juncea）.In the presence of Cd stress,phytochalatins（PCs） were induced,and Cd ions in extracts were associated with the induced PCs.So four different Cd species,PC3-Cd,PC2-Cd,glutathione（GSH）-Cd and Cys-Cd,were detected in the samples,which demonstrated that PCs were enzymatically synthesized from glutathione（GSH,Glu-Cys-Gly） by the constitutive enzyme PC synthase.The results indicated that GSH-Cd exists as the main species in leaf samples while PC2-Cd is the main species in root samples.A non-oxidizing（nitrogen） preparation environment and a-70 ℃ preservation condition were employed to avoid the oxidation of sulfhydryl groups.