The 5-HT BSA/Conjugate Control was prepared by cross-linking 5-HT creatinine sulfate complex to BSA with paraformaldehyde. Pre-adsorption of Serotonin antisera, diluted according to the antibody specification sheet, with 20 µg/ml Serotonin/BSA conjugate following the instructions below provides complete blockage of Serotonin immunolabeling. The conjugate is provided as 50 µg of lyophilized Serotonin creatinine sulfate coupled to BSA with paraformaldehyde.