Alcian blue or alcian blue is any member of a family of polyvalent basic dyes, of which the Alcian blue 8G (also called Ingrain blue 1, and C.I. 74240, formerly called Alcian blue 8GX from the name of a batch of an ICI product) has been historically the most common and the most reliable member.[1] It is used to stain acidic polysaccharides such as glycosaminoglycans in cartilages and other body structures, some types of mucopolysaccharides, sialylated glycocalyx of cells etc. For many of these targets it is one of the most widely used cationic dyes for both light and electron microscopy. Use of alcian blue has historically been a popular staining method in histology especially for light microscopy in paraffin embedded sections and in semithin resin sections.

C.I. 74240
Dye Content: >50%
Molecular Formula: C56H68Cl4CuN16S4
Molecular Weight 1298.86 g/mol
Melting Point: 148°C
Absorbtion Max: 615nm in Water