Derivatization of phytochelatins from Silene vulgaris, induced upon exposure to arsenic and cadmium: Comparison of derivatization with Ellman's reagent and monobromobimane.

Phytochelatins (PCs) are a family of thiol-rich peptides, with the general structure (γ-Glu-Cys)(n)-Gly, with n = 2-11, induced in plants upon exposure to excessive amounts of heavy metals and some metalloids, such as arsenic. Two types of PC analyses are currently used, i.e., acid extraction and separation on HPLC with either precolumn derivatization (pH 8.2) with monobromobimane (mBBr) or postcolumn derivatization (pH 7.8) with Ellman's reagent [5,5'-dithiobis(2-nitrobenzoic acid), DTNB]. Although both methods were satisfactory for analysis of Cd-induced PCs, formation of (RS)