Method for determining average solution properties of macromolecules by the injection method

A method to determine the weight average molar mass Mw, mean square radius <rg2>, and 2nd virial coefficient A2 of an unfractionated sample comprising the steps of

• A) preparing a series of n dilutions of said sample in a suitable solvent means, said dilutions spanning a range of concentrations of about an order of magnitude;
• B) providing solvent means reservoir;
• C) providing pumping means by which said solvent means may be made to flow sequentially through a multiangle light scattering detection means and a concentration detection means;
• D) sequentially injecting an aliquot of each said n sample dilutions;
• E) collecting and storing said multiangle light scattering and concentration data in computer means at preselected flow volumetric incremental intervals, Δν, throughout each said aliquot's elution as it passes through said multiangle light scattering and concentration detector means;
• F) forming the n sums corresponding to said n sample injections by said computer means, C j = ∑ i ⁢ ⁢ c ij ,
• where j=1 to n, from said collected concentration data values, cij, over the entire concentration elution elements ij of each said sample dilution j;
• G) forming the n sums corresponding to said n sample injections by said computer means, D j = ∑ i ⁢ ⁢ c ij 2 ,
• where j=1 to n, from said collected concentration data values, cij, over the entire concentration elution elements ij of each said sample dilution j;
• H) calculating the excess Rayleigh ratios Rij(θk) from said collected light scattering data at each scattering angle θk for each said sample dilution j and each elution i;
• I) forming the n sums ℜ j ⁢ ⁢ ( θ k ) = ∑ i ⁢ ⁢ R ij ⁢ ⁢ ( θ k ) ,
• j=1 to n, for each scattering angle θk and sample dilution j, by said computer means, over the entire light scattering elution elements i of said sample dilution j;
• J) forming the ratios Dj/Cj=κj;
• K) using said ratios κj and said sums j(θk) for all angles k and n sample dilutions to derive said weight average molar mass, said mean square radius, and said 2nd virial coefficient of said unfractionated sample.