Methyl Red sodium salt

Methyl red is an indicator dye that turns red in acidic solutions. It is a pH indicator, turning red under pH 4.4, yellow over pH 6.2, and orange in between those values. It is used in microbiology in the Voges-Proskauer test to identify bacteria that produce stable acids through mixed acid fermentation of glucose. Methyl-red positive bacteria include Proteus vulgaris and Escherichia coli. Methyl-red negative bacteria include Enterobacter aerogenes and Serratia marcescens.

This Thermo Scientific Chemicals brand product was originally part of the Alfa Aesar product portfolio. Some documentation and label information may refer to the legacy brand. The original Alfa Aesar product / item code or SKU reference has not changed as a part of the brand transition to Thermo Scientific Chemicals.

Applications
Methyl red is an indicator dye that turns red in acidic solutions. It is a pH indicator, turning red under pH 4.4, yellow over pH 6.2, and orange in between those values. It is used in microbiology in the Voges-Proskauer test to identify bacteria that produce stable acids through mixed acid fermentation of glucose. Methyl-red positive bacteria include Proteus vulgaris and Escherichia coli. Methyl-red negative bacteria include Enterobacter aerogenes and Serratia marcescens.

Solubility
Soluble in water (800 mg/ml at 25°C), and slightly soluble in ethanol at (25°C).

Notes
Store at room temperature. Reactive with oxidizing agents.