Takatori T, Yamaoka A, Terazawa K
J Immunol Methods. 1979;29(2):185-90. doi: 10.1016/0022-1759(79)90068-1.
The determination of pyrazolone derivatives by radioimmunoassay has been reported. Anti-antipyrine antisera were obtained by repeated immunization of rabbits with 4-azoantipyrine-conjugated bovine serum albumin. The level at least as low as 1.0 ng of antipyrine could be detected by this procedure. Various substituents on the carbon 4 position of the pyrazolone ring as well as the lack of methyl group on the nitrogen 2 position decreased the affinity for the antibody, and the antibody showed no cross-reaction with any pyrazolidine derivatives.