Why does the column turn violet upon addition of the sample/buffer containing guanidine-HCl?
Why does the column turn violet upon addition of the sample/buffer containing guanidine-HCl?
Violet color in the guanidine-HCl buffer is normal. It is caused by a weak coordination of the guanidine to the metal, causing a change in the spin energy of the d-orbital electrons that give cobalt its pink color, which slightly alters the hue of the metal ion’s color. This does not affect the binding capacity or the affinity characteristics of the column material. Imidazole binding to the metal will have a similar effect.