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

Methyl Orange Solution

Methyl Orange Solution Dissolve 0.1 g of methyl orange in 80 mL of water and add sufficient ethanol (96%) to produce 100 mL.

Complies with the following test.

Sensitivity A mixture of 0.1 mL of the solution and 100 mL of carbon dioxide-free water is yellow. Not more than 0.1 mL of 1m hydrochloric acid VS is required to change the colour of the solution to red.

Colour change pH 3.0 (red) to 4.4 (yellow).