Aqueous solution of 3 weak acids at a molar concentration of 0.0125 mol/L (ethanoic acid, o-boric acid, and phosphoric acid).
The pH becomes linear between 2 and 12 upon the addition of 0.1 mol/L sodium hydroxide.
Used in determining the predominant acid and basic forms of a color indicator such as BBT.

Specification:
Appearance: colorless liquid
Density: 1,000 g/cm3 at 20°C
Solubility in H2O: soluble