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

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 degrees C preservation condition were employed to avoid the oxidation of sulfhydryl groups.