Methyl Red Sodium Salt C.I. 13020


Methyl Red sodium salt is the sodium salt of Methyl Red. 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.

  • pH Indicator
  • Identification of bacteria in Microbiology


Dye Content: >90%
Molecular Formula: C15H14N3NaO3
Molecular Weight: 291.29 g/mol
Transition Range: pH4.2 (Violet Red) – pH6.2 (Brownish/Yellow)
Maximum Absorption (pH4.2): 523-527nm
Maximum Absorption (pH6.2): 430-434nm
Absorptivity(A1%/1cm@pH4.2): 1200-1300
Absorptivity(A1%/1cm@pH4.2): 675-735
Loss on Drying: <5%

Hazard Phrases: Not considered harmful under normal laboratory conditions

Cas No: 845-10-3
Einecs No: 212-682-9

HS CODE: 29270000


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