electrophoretic mobility, μ

https://dx.doi.org/10.1351/goldbook.E02024
The observed rate of migration of a component (v) divided by electric field strength (E) in a given medium.
Notes:
  1. Mobilities are sometimes expressed with a negative sign, because migration of the solutes or particles generally occurs in the direction opposite to the electrophoretic field (which is taken as reference for that direction).
  2. In a solid support medium, only apparent values can be determined.
Source:
PAC, 1994, 66, 891 (Quantities and units for electrophoresis in the clinical laboratory (IUPAC Recommendations 1994)) on page 894