Amines & Amides Available — Bulk Only

Methylene Blue

CAS 61-73-4 · Formula C16H18ClN3S · MW 319.9 g/mol

A deep-blue thiazine dye that serves equally as a microscopy stain and a redox indicator. It is used as a dye for paper, silk, cotton, wool, and leather, as a biological and bacteriological stain, and as a redox indicator and reagent in oxidation-reduction titrations.

Request SDS
HS Code
3204.13
At a Glance
Material Family
Amines & Amides
Record Type
Pure compound
Primary Role
Crosslinking / Curing · pH Adjustment
Functional Roles
BASIC BLUE 9
HAIR DYEING
Industries Served
Applications & Use Cases
  • Dyeing: Colorant for paper, textiles, silk, and leather
  • Biological staining: Bacteriological and microscopy stain
  • Redox indicator: Indicator in oxidation-reduction titrations
  • Laboratory reagent: Chemical reagent and colorimetric agent
Physical Properties
Melting Point
100 to 110 °C (with decomposition)
Solubility
In water, 43,600 mg/L at 25 °C
Vapor Pressure
0.00000013
Safety & Handling
Full SDS available on request

A grade-specific Safety Data Sheet (SDS) — with the complete hazard classification, handling precautions, and transport information — is supplied with every shipment and available on request. Confirm all safety and regulatory details against the SDS for your specific grade.

Request SDS →
HS / Tariff Classification
Harmonized System (HS) Code — 6-digit international heading
3204 . 13
Chapter 32
Tanning or dyeing extracts; pigments; paints and varnishes
Heading 32.04
Internationally harmonized (WCO HS)
Subheading 3204.13
6-digit international code — national tariff line adds further digits
Chemical Identity
CAS Number
61-73-4
Molecular Formula
C16H18ClN3S
Molecular Weight
319.9 g/mol
IUPAC Name
[7-(dimethylamino)phenothiazin-3-ylidene]-dimethylazanium chloride
INCI Name
BASIC BLUE 9
PubChem CID
InChI Key
CXKWCBBOMKCUKX-UHFFFAOYSA-M
Synonyms & Trade Names
methylene blue Basic blue 9 Methylthioninium chloride Solvent blue 8 Swiss Blue Methylene Blue anhydrous Chromosmon C.I. Basic Blue 9 Methylene Blue N Methylthionine chloride Methylene Blue BB Methylene Blue chloride Methylenium ceruleum Urolene blue Bleu de methylene Methylene Blue A Methylene Blue B Methylene Blue D Methylene Blue G
Full Description

Methylene blue (CAS 61-73-4) is a synthetic cationic thiazine (azine) dye supplied to USP specification. It is used as a dye for paper, silk, cotton, wool, and leather, as a biological and bacteriological stain, and as a redox indicator and reagent in oxidation-reduction titrations.

Frequently Asked Questions

What is the use of methylene blue USP?

Methylene blue (CAS 61-73-4) is a synthetic cationic thiazine dye supplied to USP specification. It is used as a dye for paper, silk, cotton, wool, and leather; as a biological and bacteriological stain; and as a redox indicator and reagent in oxidation-reduction titrations. RawSource supplies it in bulk for dyeing, laboratory, and reagent use.

What does USP mean on methylene blue?

USP indicates the material meets the United States Pharmacopeia compendial specification for identity and purity. RawSource supplies methylene blue to USP grade with a Certificate of Analysis documenting conformance.

What type of compound is methylene blue?

It is a synthetic cationic thiazine (azine) dye, formula C16H18ClN3S, CAS 61-73-4. The cationic dye structure is the basis of both its textile-dyeing affinity and its function as a redox indicator.

What is methylene blue used for in the laboratory?

It serves as a biological and bacteriological stain for microscopy, as a redox indicator in oxidation-reduction titrations, and as a general colorimetric reagent. The HS code is 3204.13 (basic dyes).

What bulk packaging and documentation are available?

RawSource supplies USP-grade methylene blue in bulk with a Certificate of Analysis and Safety Data Sheet per shipment. Request a bulk quote with your target volume and grade for current pricing and lead time.

Disclaimer. Information on this page — including properties, identifiers, hazard, transport (DOT/UN) and tariff (HS) classifications, and applications — is provided for general reference and is compiled from authoritative public sources (e.g. PubChem/ECHA, 49 CFR 172.101, the Harmonized Tariff Schedule). Values are typical and are not a guaranteed specification; the Certificate of Analysis (CoA) for the lot purchased governs. Products are sold for industrial and professional use only. Nothing here is a medical, health, or efficacy claim or advice. Always consult the current Safety Data Sheet (SDS) before handling, storage, transport or disposal, and confirm regulatory status, classification and suitability for your application and jurisdiction. Hazard, transport and tariff classifications must be verified for your specific shipment. RawSource makes no warranty, express or implied, and assumes no liability for use of this information. Trademarks. Third-party trademarks and brand names are the property of their respective owners; any reference is nominative — used only to identify a comparable product — and does not imply affiliation with, sponsorship by, or endorsement by the trademark owner.