SEQ-NMR: A new tool for measuring distribution coefficients and pore size in chromatography media
(English)Manuscript (preprint) (Other academic)
We present a new method, SEQ-NMR (size-exclusion quantification NMR spectroscopy) for measuring equilibrium distribution coefficients, Keq, in chromatography media. The same method is also generally applicable to measure pore sizes in any porous media. Keq versus probe size, the selectivity curve, is obtained by equilibrating a chromatographic medium with a solution of polymers with a broad size distribution. The solution before and after equilibration is analyzed with NMR diffusion experiments. The joint least-squares analysis of the two diffusion attenuation curves under suitable constraints provides the extent by which the different polymer fractions are diluted upon equilibration that in turn yields the selectivity curve. The relation of the applied procedure to Inverse Laplace transformation is clarified. Simulations probe the performance of the method, in particular with respect to signal-to-noise ratio (SNR) and other parameters used in the data inversion process. The method is demonstrated experimentally using dextran polymers and the chromatographic medium Sephacryl™ S-200 High Resolution for which it yields, within a cylindrical pore model, 6.9 nm for the average hydrated pore size. Comparison is made to the analysis of the same system with inverse size-exclusion chromatography (ISEC). Advantages of the method, primarily that in speed, potential for automation, and small sample size, are discussed.
nuclear magnetic resonance, NMR, chromatography, distribution coefficient, partition coefficient, diffusion, pore size
Research subject Chemistry
IdentifiersURN: urn:nbn:se:kth:diva-204568OAI: oai:DiVA.org:kth-204568DiVA: diva2:1085264
FunderSwedish Research Council
QC 201704182017-03-282017-03-282017-04-18Bibliographically approved