A GENERALIZED SEPARATION REACTION SCHEME FOR ASSESSMENT OF THE RADIOANALYTICAL METHOD OF CONCENTRATION-DEPENDENT DISTRIBUTION

For the assessment of the analytical error of concentration dependent distribution (CDD), complex-forming separation reaction was proposed i n a generalized form of equilibrium ML[n]+ + nL reversible MLBAR[nBAR] , where n is the effective stoichiometric coefficient, i.e . the diffe rence of mean ligand numbers [nBAR] and [n] of a mixture of complexes of analyte M with reagent L in the respective groups (distinguished by bars above the symbols) of the separation system. Calibration curve I = A/ABAR is derived from measurement of gross activity of complexes, A = A(ML[n]) and ABAR = A(MLBAR[nBAR]). Theoretical relative error is expressed as a product of three terms, deltax/x = f1f2f3. The first te nn f1 depends on the degree of isotopic dilution, and the recommended ratio of amounts of nonradioactive (x) and radioactive (y) substance M is x/y is-an-element-of (1;4). The second term f2 depends first of al l on the slope of distribution ratio (yield of separation RBAR) vs. th e analyte ; reagent ratio, n(Z + 1)/T. The form of slope is analyzed o n the basis of the generalized separation reaction. Optimal conditions were discussed from this point of view and the ideal case is at f2 = 1. The third term f3 depends on the activities A and ABAR, i.e. on the distribution ratio, sample volumes, and the manner of counting. The i deal ratio of sample activities is A = ABAR and the optimal interval R BAR is-an-element-of (0.2; 0.8) is suggested