... staining solution [36]; (c) azinc-imidazole stain [37]; and (d) a copper stain [38], aswell as their impact on the further processing of pro-teins by MS. In all staining methods, except for the conventional ... proteins visualized by reversiblenegative staining using imidazole-zinc salts. Electropho-resis 20, 732–737.38 Lee C, Levin A & Branton D (1987) Copper staining: afive-minute protein stain ... stain, the pH was kept nearlyneutral. Most protein spots were detectable using aconventional Coomassie staining protocol or the zinc-imidazole stain, respectively, whereas the copper stainand...