Fig. 4. PCs and Hg-PC complexes detected by HPLC-ESI-MS(TOF).(a) Examples of free PCs and Hg-PCs found in shoots and roots of Col-0 plants exposed to 3 µM Hg for 72 h. Chromatographs and characteristic MS spectra of several molecular ions are shown (in negative mode). (b) Summary table describing the different molecular ions of biothiol ligands and Hg-PC complexes detected in shoots and roots of all Arabidopsis genotypes treated with 3 µM Hg for 72 h. HPLC-ESI-MS(TOF) was carried out in negative and positive modes, and major detected molecular ions (m/z ) are shown.