• British Pharmacopoeia Volume V
  • Appendices
  • Appendix I A. General Reagents

Methyl Orange

Methyl Orange CI 13025; Sodium 4′-dimethylaminoazobenzene-4-sulfonate; C14H14N3NaO3S = 327.3 (547-58-0)

Produces a red colour in moderately acidic solutions and a yellow colour in weakly acidic and alkaline solutions.