The competitive Serotonin Ultrasensitive ELISA kit uses the microtiter plate format. Derivated serotonin competes for a fixed number of antiserum binding sites. When the system is in equilibrium, free Antigens and free Antigens-antiserum complexes are removed by washing. The antibody bound to the solid phase serotonin is detected by anti-rabbit/peroxidase. The substrate TMB / peroxidase reaction is monitored at 450 nm. The amount of antibody bound to the solid phase serotonin is inversely proportional to the serotonin concentration of the sample. Sample Types: biological fluids. Range: 0.67 - 20 pg/sample. Sensitivity: 0.39 pg/sample. Time: Overnight ? Serotonin (5-Hydroxytryptamine), a biogenic amine, is a product of the tryptophan metabolism. It is a well evaluated neurotransmitter of the central nervous system and can be found in high concentrations in the chromaffine cells of the intestinal mucosa, in the platelets and the serotonergic neurones of the brain. Central-serotonergic neurones influence physiological functions such as sleep and the hormonal and cardio-vascular regulation. Increased serum levels can be found with malignant carcinoid, endogenous depression and schizophrenia.