Patent ID: 8195405

Claim:
A method for determining values of equilibrium association constants, stoichiometries of association, incompetent fractions, second and third virial coefficients, and/or molar masses corresponding to self-association of reversibly associating macromolecules in solution at high concentration in a solvent, comprising the steps of: 1. introducing a series of k aliquots of solutions of the molecule of interest at concentrations c f , f=1. . . k of into a light scattering photometer, whereby said light scattering photometer i. illuminates each injected diluted aliquot by a light beam and ii. detects the intensity of light scattered therefrom at one or more angular locations θ at which is placed a light sensitive detector; 2. determining the concentration c f of each diluted aliquot f; 3. forming the excess Rayleigh ratios R(c f ,θ) from said detected scattered light intensities; 4. representing said excess Rayleigh ratios to correct for thermodynamic non-ideality in terms of said k dilutions c f, f=1 . . . k as R ⁡ ( c f , θ ) K = ( ⅆ n ⅆ c ) 2 ⁢ ∑ i ⁢ ⅈ ⁢ ⁢ M ⁢ ⁢ c f , i ⁢ P i ⁡ ( θ ) 1 + 2 ⁢ A 2 ⁢ M ⁢ ⁢ c f ( c f - 16 ⁢ π 2 3 ⁢ λ 2 ⁢ ∑ i ⁢ c f , i ⁢ 〈 r g 2 〉 i ⁢ sin 2 ⁡ ( θ / 2 ) ) + 3 ⁢ A 3 ⁢ M ⁢ ∑ i ⁢ ( c f , i ) 2 , wherein M is the molar mass of the monomer, i the order of each self-associating i-mer, c f,i the partial equilibrium concentration of the i-mer in the f th diluted aliquot, P i ⁡ ( θ ) = 1 - 16 ⁢ π 2 3 ⁢ λ 2 ⁢ 〈 r g 2 〉 i ⁢ sin 2 ⁡ ( θ / 2 ) , λ is the wavelength of said illuminating light beam, r g 2 the mean square radius of the i-mer, K = 4 ⁢ π 2 ⁢ n 2 N A ⁢ λ 4 , n the refractive index of said solution, N A Avogadro's number, and dn/dc the refractive increment of said macromolecule in said solution; 5. fitting said representations of said excess Rayleigh ratios to the equations of an association model; and 6. determining from said fitted representations the values of equilibrium association constants, stoichiometries of association, incompetent fractions, second and third virial coefficients, and/or molar masses.