The algebraic sum of the charges present at the surface of the particle divided by the @E02032@ of the @P04906@. The symbol \(z\) is also used for @C00993@ of an ion.
Source: PAC, 1994, 66, 891. (Quantities and units for electrophoresis in the clinical laboratory (IUPAC Recommendations 1994)) on page 895 [Terms] [Paper]