Phenol Red Solution

Dissolve 0.1 g of phenol red in 2.82 mL of 0.1m sodium hydroxide and 20 mL of ethanol (96%) and add sufficient water to produce 100 mL.

Complies with the following test.

Sensitivity A mixture of 0.1 mL 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 reddish violet.

Colour change pH 6.8 (yellow) to pH 8.4 (reddish violet).