reference value pH standard
An aqueous solution of \(0.05\ \text{mol}\) potassium hydrogen phthalate per kg water which is the reference value for the definition of pH(RVS) values in the temperature range \(0\)-\(95\ ^{\,\unicode{x26ac}}\text{C}\).
See also:
operational pH standard
primary pH standard
PAC, 1985, 57, 531. (Definition of pH scales, standard reference values, measurement of pH and related terminology (Recommendations 1984)) on page 540 [Terms] [Paper]