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Methyl blue is a chemical compound with the molecular formula C37H27N3Na2O9S3. It is used as a stain in histology,[1] and stains collagen blue in tissue sections. It can be used in some differential staining techniques such as Mallory's connective tissue stain and Gömöri trichrome stain, and can be used to mediate electron transfer in microbial fuel cells. Fungal cell walls are also stained by methyl blue.

Methyl blue
Methyl blue.png
Methyl Blue 3D.png
Sample of Methyl Blue.jpg
Solid methyl blue
Methyl Blue aqueous solution.jpg
Methyl blue aqueous solution
Other names
Cotton blue, Helvetia blue, Acid blue 93, C.I. 42780
3D model (JSmol)
ECHA InfoCard 100.044.852
Molar mass 799.814 g/mol
Appearance red solid
Soluble in water, slightly soluble in ethanol
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oilHealth code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Methyl blue is also available in mixture with water blue, under name Aniline Blue WS, Aniline blue, China blue, or Soluble blue.

See alsoEdit


  1. ^ R. W. Sabnis (2010). Handbook of Biological Dyes and Stains: Synthesis and Industrial Applications. John Wiley & Sons. p. 24.