Methylene Blue: Compound Profile And Analytical Considerations

Methylene blue (methylthioninium chloride) is one of the oldest synthetic compounds still in active use. First produced in 1876 as a textile dye, it has been used since as a biological stain, a redox indicator and a reagent, and it remains a common subject of laboratory characterisation.

Chemically it is a phenothiazine-derived cationic dye. It is redox-active — it can accept and donate electrons, moving between a blue oxidised form and a colourless reduced form — which is what makes it useful as an indicator and is the property most laboratory work with it depends on.

Its physicochemical behaviour — solubility, redox potential and stability in solution — is concentration-dependent, which is why the stated concentration of a material matters as much as its identity. A 1% solution and a 3% solution are not interchangeable in a protocol, and a solution whose concentration is not stated cannot be used reproducibly.

Methylene blue is also intensely pigmented: it stains skin, fabric and laboratory surfaces on contact, and dilute solutions remain strongly coloured. Handle it with gloves in a suitable workspace and store it sealed and out of direct light.

Ablabs supplies methylene blue for laboratory research use only. It is not supplied for human or animal consumption, and nothing on this page is guidance on use.