Assay of Methylene Blue

The application provides a method to determine assay of methylene blue using photometric titration by exploiting its redox properties.

Background

Methylene blue is a commonly used dye that exhibits array of biological properties. The intravenous form of methylene blue is approved by the FDA for treatment of pediatric and adult patients with acquired methemoglobinemia. It also has photosensitizing properties and finds its application in photodynamic therapies for topical treatment of dermatologic or mucocutaneous infections like herpes eczema etc.

Apart from its impressive range of biological activities, methylene blue also acts as an oxidation-reduction agent. It is widely used as a redox indicator for variety of applications. The solutions of this dye are blue in an oxidizing environment whereas turn colorless when exposed to a reducing agent. This redox property of methylene blue has been exploited in this application note for its quantitative estimation.

Ascorbic acid, a mild reducing agent reacts with the methylene blue molecule in acidic conditions forming a colorless hydrogenated molecule leucomethylene blue. This color change from blue to colorless is monitored using a Photometric sensor at 660 nm.

This application note includes:

• Introduction
• Sample Preparation and Procedures
• Solutions and Chemicals
• Chemistry
• Instruments and Accessories
• Method in Detail
• Results and Remarks

And method files (.lmt and .xml) for direct import and implementation on the instrument.