A method to determine the weight average molar mass M, the mean square radius < r g 2 >, 2 nd virial coefficient A 2, and 3 rd virial coefficient A 3 of a solution of molecules in a solvent, comprising the steps of A. providing a reservoir of said solvent; B. providing a reservoir of said solution; C. preparing from said reservoir of said solvent and said reservoir of said solution a series of n total dilutions D m, where m is 1 to n, of said solution, using a dilution means, by said solvent; D. providing sampling means by which said dilutions D m, where m = 1 to n, are sequentially injected and made to flow through serially a. a light scattering detection means that collects light scattered at a plurality of q total angles θ k, where k is 1 = q at each incremental injection volume Δ v i of said dilution D m, where m = 1 to n; b. a concentration detection means that measures the corresponding molecular concentrations c mi, where m = 1 to n, and n is the total number of dilutions, at each incremental injection volume Δ v i of said dilution D m, where m = 1 to n i and n is the total number of di-lutions; E. generating from the measured scattered light intensities and the corresponding concentration c mi at each flow volumetric incremental interval Δ v i the associated excess Rayleigh ratios R *(θ k, c mi); F. calculating the n concentration sums C m = ∑ i c m i Δ v i corresponding to each said dilution D m, where m =1 to n, and n is the total number of dilutions, from said molecular concentrations, c mi, over the entire elution of each said dilution D m; G. calculating the 3 qn excess Rayleigh ratios sums, R 1, m k = ∑ i R * θ k c m l Δ v i, where k = 1 to q and m = 1 to n, R 2, m k = ∑ i R * θ k c m i 2 Δ v i, and R 3, m k = ∑ i R * θ k c m i 3 Δ v i, corresponding to said n total dilutions, from said generated excess Rayleigh ratios R *(θ k, c mi); extracting said average molecular properties of said solution of molecules from said 3 qn excess Rayleigh ratios sums by fitting the collected concentration values and generated excess Rayleigh ratio values with the equation C mk = 1 M ⁢ R 1, mk + P 1 M ⁢ sin 2 θ k 2 + R 1, mk - P 2 M ⁢ sin 4 θ k 2 ⁢ R 1, mk + 2 ⁢ A 2 M ⁢ R 2, mk + 2 ⁢ A 2 ⁢ P 1 M ⁢ sin 2 θ k 2 ⁢ R 2, mk + 3 ⁢ A 3 M + 4 ⁢ A 2 2 M 2 ⁢ R 3, mk, where P 1 = 4 ⁢ κ 2 3 〈 r g 2 〉, P 2 = 4 ⁢ κ 4 45 ⁢ 10 ⁢ 〈 r g 2 〉 2 - 3 〈 r g 4 〉, κ = 2 ⁢ π n 0 λ 0, n 0 is the refractive index of the solvent and □ 0 is the incident vacuum wavelength of said light scattering detection means, and the weight average molar mass M, the mean square radius < r g 2 >, the 2 nd virial coefficient A 2, and the 3 rd virial coefficient A 3 are the parameters of the fit. A. providing a reservoir of said solvent; B. providing a reservoir of said solution; C. preparing from said reservoir of said solvent and said reservoir of said solution a series of n total dilutions D m, where m is 1 to n, of said solution, using a dilution means, by said solvent; D. providing sampling means by which said dilutions D m, where m = 1 to n, are sequentially injected and made to flow through serially a. a light scattering detection means that collects light scattered at a plurality of q total angles θ k, where k is 1 = q at each incremental injection volume Δ v i of said dilution D m, where m = 1 to n; b. a concentration detection means that measures the corresponding molecular concentrations c mi, where m = 1 to n, and n is the total number of dilutions, at each incremental injection volume Δ v i of said dilution D m, where m = 1 to n i and n is the total number of di-lutions; a. a light scattering detection means that collects light scattered at a plurality of q total angles θ k, where k is 1 = q at each incremental injection volume Δ v i of said dilution D m, where m = 1 to n; b. a concentration detection means that measures the corresponding molecular concentrations c mi, where m = 1 to n, and n is the total number of dilutions, at each incremental injection volume Δ v i of said dilution D m, where m = 1 to n i and n is the total number of di-lutions; E. generating from the measured scattered light intensities and the corresponding concentration c mi at each flow volumetric incremental interval Δ v i the associated excess Rayleigh ratios R *(θ k, c mi); F. calculating the n concentration sums C m = ∑ i c m i Δ v i corresponding to each said dilution D m, where m =1 to n, and n is the total number of dilutions, from said molecular concentrations, c mi, over the entire elution of each said dilution D m; G. calculating the 3 qn excess Rayleigh ratios sums, R 1, m k = ∑ i R * θ k c m l Δ v i, where k = 1 to q and m = 1 to n, R 2, m k = ∑ i R * θ k c m i 2 Δ v i, and R 3, m k = ∑ i R * θ k c m i 3 Δ v i, corresponding to said n total dilutions, from said generated excess Rayleigh ratios R *(θ k, c mi);