Validation of a kinetic model for the reactions in RIA.

The goal of this work was to check the validity of a model previously described for the study of kinetics of the processes taking place during the immuno-analytical measurement of insulin. The antibody was immobilized on the suface wall of the reaction tube. Tracer and insulin concentration, temperature, viscosity and ionic strength in the reaction medium were taken as independent variables. Biexponential kinetics depending on the concentration was observed. The results of the viscosity study show a clear negative influence of this parameter on the direct reaction velocity. Ionic strength had a slight effect, which suggests that the observed variation due to the addition of glycerol is not induced by the influence of the dielectric constant of the solution used. The effect of the temperature shows activation parameters similar to water flow-viscosity energy, which suggests a diffusion control for the reaction. The proposed model correctly interprets the influence of the studied variables.