Aniline Blue WS

Aniline Blue WS, also called aniline blue, diphenylamine blue, China blue, or Soluble blue, is a mixture of methyl blue and water blue. It may also be either one of them.^[1] It is a soluble dye used as a biological dye,^[2] in fluorescence microscopy, appearing a yellow-green colour after excitation with violet light.^[3] It is a mixture of the trisulfonates of triphenyl rosaniline and of diphenyl rosaniline.^[4]

Water blue

Methyl blue

Aniline blue or its constituents are used to stain collagen, as the fibre stain in Masson's trichrome,^[5] as well as to reveal callose structures in plant tissues.^[6]

It can also be used in other connective tissue stains, such as Mallory's stain,^[5] Gömöri trichrome stain, and Carstair's Method.^[7] It is used in differential staining.