Capillary zone electrophoresis (CZE), also called free solution capillary electrophoresis, is the most straightforward form of CE. It separates molecules based on their charge-to-mass ratio. The uniformity of the buffer solution and consistent electric field strength along the capillary's length are essential to CZE. Once voltage is applied after sample injection, the components of the sample spread out into distinct zones within the capillary. The primary factor driving this separation is the electrophoretic mobility (µep), which can be estimated using the Debye-Huckel-Henry theory. CZE can effectively separate both large and small molecules. Even for small molecules with minimal differences in charge-to-mass ratios, CZE can still achieve separation.