Methyl blue in solid form and as aqueous solution.
| IUPAC name
| Other names
Acid blue 93
Brilliant Lake Blue G
Sodium triphenyl-p-rosaniline trisulfate
|Molar mass||799.814 g/mol|
|Appearance||Dark crimson/red powder|
|Solubility||Slightly soluble in ethanol|
|Safety data sheet||Santa Cruz Biotechnology|
|Lethal dose or concentration (LD, LC):|
LD50 (Median dose)
|5000 mg/kg (oral, rat)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Methyl blue (IUPAC name: 4-[4-[[4-(4-sulfoanilino)phenyl]-[4-(4-sulfophenyl)iminocyclohexa-2,5-dien-1-ylidene]methyl]anilino]benzenesulfonic acid) is an organic compound used as stain in histology, as it can stain collagen blue in tissue sections. It's chemical formula is C37H27N3Na2O9S3.
Methyl blue will turn blue when dissolved in water. Aqueous solutions will turn nearly colorless in about 2-3 days in open air, with diluted solutions being more sensible.
Methyl blue is a dark red or black-purple solid (depending on the crystallization solvent and age), soluble in water (7 g/100 ml), where it turns deep blue, similar property to that of methylene blue. Aqueous solutions with a concentration of 10 g/l have a pH of 5 at standard conditions. Methyl blue has a bulk density of 0.670 g/cm3. 
Methyl blue is sold by various chemical suppliers. It can also be bought online.
Methyl blue is best bought than made.
- Stain collagen in tissues
- Make Aniline Blue WS
Methyl blue shows little toxicity, but will stain anything it touches blue and it's difficult to remove.
Methyl blue should be kept in closed bottles, away from corrosive vapors.
Methyl blue doesn't require special disposal and can be safely poured down the drain with lots of water.