Unidad de Investigacion y Desarrollo 1 article published in JoVE Biochemistry Capillary Electrophoresis Separation of Monoclonal Antibody Isoforms Using a Neutral Capillary Carlos Eduardo Espinosa-de la Garza*1, Rodolfo Daniel Salazar-Flores*1, Néstor Octavio Pérez1, Luis Francisco Flores-Ortiz1, Emilio Medina-Rivero1 1Unidad de Investigación y Desarrollo, Probiomed S.A. de C.V. Here, we present a comprehensive capillary zone electrophoresis protocol for the assessment of intrinsic physicochemical heterogeneity of monoclonal antibodies as a quality attribute.