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

Bromothymol Blue Solution R1
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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 (pH range, 6.0 to 7.6).

Complies with the following test.

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.