Capillary electrophoresis (CE) is an analytical technique that separates ions based on their electrophoretic mobility in submillimeter capillaries with the use of an applied voltage. The electrophoretic mobility depends on the charge of the molecule, the viscosity, and the atom's radius. Very often, CE refers to capillary zone electrophoresis (CZE), but other electrophoretic techniques including capillary gel electrophoresis (CGE), capillary isoelectric focusing (CIEF), capillary isotachophoresis, and micellar electrokinetic chromatography (MEKC) also belong to this class of methods
(Kemp, 1998; Li, 1992). Recio, Amigo, and Lopez-Fandino (1997) published a review on the use of CE in the assessment of dairy products quality and, more recently, Kvasnicka (2005) published a complete review of the applications of CE in food authenticity control. A method to detect adulteration of goat and ewe cheeses with cow's milk by CZE and UV detection is suggested by Cartoni, Coccioli, Jasionowska, and Masci (1999). The authors analyzed the nitrogen compounds extracted by water and acetic acid solution from goat and sheep cheeses. Peaks detected were attributed to the whey proteins, and the area ration between p-lactoglobulin A of cow and a- lactalbumin of goat was used as parameter to evaluate the cow milk addition in goat milk and cheese. The percentages of cow milk detectable with this method were 2% in goat milk and 4% in goat cheese whereas, when goat and sheep cheese were analyzed, only qualitative results could be obtained. Similar results were achieved by Muller et al. (2008) using CE coupled with an ion trap mass spectrometer, but in this case all the three species were analyzed and the minimum percentage of cow milk detectable was 5%.