The \(\text{pH}\) value at which the net @[email protected] of an @[email protected] is zero. \(\text{pI}\) is a commonly used symbol for this @[email protected] It should be replaced by \(\text{pH(I)}\) because it is a \(\text{pH}\) determined under that particular condition.
PAC, 1972, 31, 577. (Manual of Symbols and Terminology for Physicochemical Quantities and Units, Appendix II: Definitions, Terminology and Symbols in Colloid and Surface Chemistry) on page 618 [Terms] [Paper]
PAC, 1994, 66, 891. (Quantities and units for electrophoresis in the clinical laboratory (IUPAC Recommendations 1994)) on page 894 [Terms] [Paper]