Article · Wikipedia archive · Last revised Jun 17, 2026

Azure A

Azure A is an organic compound with the chemical formula C14H14ClN3S. It is a light blue to dark blue dye. It is used as a screening test for mucopolysaccharides. It can also be used to stain lysosomes in blood smears, and is often used in Giemsa stain. It's formed via oxidation of Methylene blue.

Last revised
Jun 17, 2026
Read time
≈ 1 min
Length
159 w
Citations
1
Source
Azure A
source ↗
Names
IUPAC name
N',N'-dimethylphenothiazin-5-ium-3,7-diamine chloride
Other names
asym-Dimethylthionine Chloride; Methylene Azure A
Identifiers
3D model (JSmol)
3922287
ChEBI
ChemSpider
ECHA InfoCard 100.007.738
UNII
  • InChI=1S/C14H14N3S.ClH/c1-17(2)10-4-6-12-14(8-10)18-13-7-9(15)3-5-11(13)16-12;/h3-8H,15H2,1-2H3;1H/q+1;/p-1 checkY
    Key: PGWTYMLATMNCCZ-UHFFFAOYSA-M checkY
  • [Cl-].CN(C)c1cc2[s+]c3cc(N)ccc3nc2cc1
Properties
C14H14ClN3S
Appearance green to dark brown powder
Density 1.776
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Azure A is an organic compound with the chemical formula C14H14ClN3S. It is a light blue to dark blue dye. It is used as a screening test for mucopolysaccharides. It can also be used to stain lysosomes in blood smears, and is often used in Giemsa stain. It's formed via oxidation of Methylene blue.1

References

References

  1. "Azure A - Dyes for Histology". StainsFile. Retrieved 2025-07-28.