US EPA

2567281 

Journal Article 

Mono and biexponential models in radioimmunoassay of insulin 

Diez Montoro, R; Salabert Salvador, MaT; Moreno Frigols, JL 

2009 

75 

1 

25-41 

WOS:000270000700002 

Radioimmunoassay (RIA) is a principal method for quantifying serum Insulin concentration. We studied the influence of initial concentration of (125)I-labeled antigen (M) and unlabeled Insulin (Q), viscosity and temperature on the substitution reaction between Q and the immunocomplex (PM) formed by M and the anti-Insulin antibody (P). The accuracy of this method is critically dependent on such factors. In addition, we propose a kinetic model for this reaction. We used a commercially available RIA kit for Insulin, a gamma counter, and a viscosimeter to study the effect of initial concentration of M, ionic strength, viscosity, and temperature on the substitution reaction between M and Q. Data were analyzed using Statistica software. The apparent rate constant for the reaction between PM and Q is dependent on the initial concentrations of M and Q, and the viscosity of the reaction medium, and temperature, and independent of the ionic strength.



A kinetic model for the displacement of the (125)I-Insulin by the Insulin in its union to a specific antibody is proposed. Such model adjusts satisfactorily to the results and shows the influence of the variables studied on the sensitivity of the method of RIA on which the analytical determination of the Insulin is based. 

Concentration; Immunocomplex; Ionic Strength; Kinetics; Substitution Reaction; Temperature; Viscosity