During fasting, the availability of free glucose, including glucose substrates, decreases and fats become the predominant sources of energy for the human body. Under these conditions, there is an increase in the degradation of fatty acids to acetyl coenzyme A in the liver, with the formation of ketone bodies. Acetoacetate is primarily formed but, as a ketoacid, is unstable and is reduced to 3-hydroxybutyrate (3HB). Sensitive electrophoretic determination of 3-hydroxybutyrate (3HB) as an indicator of human ketogenesis is performed in fused silica capillary covalently coated by an anionic copolymer of poly(acrylamide-co-sodium-2-acrylamido-2-methylpropanesulphonate) (PAMAMPS).