title: Biexponential model for the kinetics of the substitution reaction in the radioimmunoassay of triiodothyronine.
abstract: The influence of initial concentrations, ionic strength, viscosity and temperature on the substitution reaction of 125I-triiodothyronine (T3) (M) by unlabelled T3 (Q) in the immunocomplex PM (P = anti-T3 antibody) has been studied, and a kinetic model is proposed. The apparent rate constant is dependent on the initial concentration of labelled and unlabelled T3, viscosity and temperature, and independent of ionic strength. The reaction is endothermic and is not controlled by diffusion. The results obtained are in line with the proposed model. We propose some modifications for optimizing the technique.
authors.affiliation: Department of Physical Chemistry, Faculty of Pharmacy, Valencia, Spainb Radioisotope Service, Valencia Hospital Clínico, Valencia, Spain
authors.forename: R
authors.initials: R
authors.lastname: Díez Montoro
authors.forename: M T
authors.initials: MT
authors.lastname: Salabert  Salvador
authors.forename: J L
authors.initials: JL
authors.lastname: Moreno Frigols
mesh_terms: D007700:Kinetics; D008954:Models, Biological; D011863:Radioimmunoassay; D014284:Triiodothyronine / Q000032:analysis*
chemical_list: D014284:Triiodothyronine