Methyleneblue (MB) is a reducing agent, which is easily soluble in water, easy to pass through the cell membrane, relatively non-toxic and side effects, and has been approved for clinical use. Methylene blue has been widely used since it was introduced into biology in the 19th century: methylene blue is used as a dye in neuroanatomy and bacteriology; In biochemical studies, methylene blue acts as an indicator of redox. As an antidote, methylene blue is used to treat methemoglobinemia caused by nitrite poisoning; At the same time, methylene blue is also used to treat cyanide poisoning and ifosfamide induced encephalopathy.

chemical property

Golden red, shiny golden yellow or shiny bronze powder. It is blue in water and slightly soluble in ethanol. The dye is yellow green in concentrated sulfuric acid and turns blue after dilution. The aqueous solution with sodium hydroxide is purple and dark purple precipitates are formed.

purpose

1) Alkaline lake blue BB is mainly used for dyeing cotton, acrylic fiber, hemp and silk. It has poor fastness and sunlight fastness of grade 2-3. It is also used for paper dyeing, bamboo and wood dyeing, ink and lake manufacturing, and also for the dyeing of biological bacterial tissues.

2) It can be used for dyeing linen, silk fabrics, paper and bamboo and wood. It can also be used to make ink and lake, and to dye biological and bacterial tissues. It can be mixed with basic violet 5bn and yellow dextrin in the ratio of 78:13:9 to form basic magenta blue.

Key Differences Between CAS 7220-79-3 and CAS 61-73-4

Structural Differences

• CAS 7220-79-3: Contains 3 water molecules in its crystal lattice, altering its physical properties (e.g., lower density, higher hygroscopicity).

• CAS 61-73-4: Anhydrous form with no bound water, often preferred for precise industrial or analytical applications.

Functional Differences

1. Pharmaceutical Use:

• Trihydrate (7220-79-3): Commonly used in USP/EP-compliant formulations (e.g., injectables, microbiological media).

• Anhydrous (61-73-4): Rarely used in drug manufacturing due to stricter hydration control requirements.

2. Industrial Use:

• Anhydrous (61-73-4): Preferred for dyeing textiles, ink production, and water treatment due to stability and cost-effectiveness.

• Trihydrate (7220-79-3): Less common in industrial settings.

3. Laboratory Use:

• Trihydrate: Used in standardized protocols (e.g., Gram staining, redox experiments like the "Blue Bottle" reaction).

• Anhydrous: Applied in spectrophotometry (e.g., absorbance at 665 nm) or cell biology (nuclear staining).

Safety and Regulatory Notes

• Toxicity: Both forms share similar toxicity profiles (e.g., rat oral LD₅₀ ≈ 1180 mg/kg).

• Labeling:

• Trihydrate (7220-79-3): Often labeled with hydration state and compliance with pharmacopeias (e.g., USP-NF).

• Anhydrous (61-73-4): Typically marked for industrial or reagent-grade use.

References

1. USP-NF Monographs: Search "Methylene Blue" on usp.org for pharmaceutical-grade specifications.

2. PubChem Data:

• CAS 7220-79-3

• CAS 61-73-4

3. Supplier Documentation: Sigma-Aldrich or TCI Chemicals provide COA (Certificate of Analysis) for purity and application details.

Summary

• Trihydrate (7220-79-3): Used in medicine/labs for controlled hydration and compliance with pharmacopeias.

• Anhydrous (61-73-4): Favored in industry and general research for cost and stability.

• Key Distinction: Hydration state drives differences in solubility, stability, and regulatory compliance.