 In aqueous solution Alcian blues continue to be metachromatic at molar concentrations one hundredth those at which toluidine blue is mainly orthochromatic.Only a very small shoulder of the absorption curve at 670–680 nm represent the monomeric dye, which is usually the minority and becomes even lesser minority (<108M) in presence of salts.However, when the solvent is DMSO—a non-protic solvent of moderately high dielectric constant, Alcian blue does not aggregate and a big monomeric absorption peak can be well visualized.