These dyes are often substituted for each other. Azocarmine without any B or G designation is sometimes all that is given as identification. In most cases, either can be used. It has been specified as the plasma stain in some trichrome methods. It should be noted that neither is an azo dye and neither has any relationship to carmine.
Since azocarmine B is more soluble in water than azocarmine A, it may be preferable to use it.
R. D. Lillie.
Conn's Biological Stains
Williams & Wilkins, Baltimore, MD., U.S.A.
Edward Gurr, (1971)
Synthetic dyes in biology, medicine and chemistry
Academic Press, London, England.