Bromothymol Blue Solution R1

Dissolve 50 mg of bromothymol blue in a mixture of 4 mL of 0.02m sodium hydroxide and 20 mL of ethanol (96%) and dilute to 100 mL with water.

Complies with the following tests.

Sensitivity A mixture of 0.3 mL of the solution and 100 mL of carbon dioxide-free water is yellow. Not more than 0.1 mL of 0.02m sodium hydroxide VS is required to change the colour of the solution to blue.

Colour change pH 5.8 (yellow) to pH 7.4 (blue).