An investigation of new commercial samples of methyl green and pyronin Y.

New commercial samples of Methyl Green (Gurr Certistain), Pyronine G (Gurr Certistain) and Pyronin Y (Polysciences) have been investigated using spectrophotometry, thin layer chromatography and nuclear magnetic resonance, in addition to standardized simultaneous and sequential staining methods using purified Ethyl Green and pure Pyronin Y as reference dyes. The Methyl Green was found to be Ethyl Green contaminated with Crystal Violet. It did not have any advantages compared with Ethyl Green supplied by American dye companies. The Pyronine G sample was Pyronin Y with a high dye content that gave good staining results when used with purified Ethyl Green. Pyronin Y from Polysciences was found to be essentially pure Pyronin Y.