Diffusion and Electrophoretic Studies Using Nuclear Magnetic Resonance

Abstract

The NMR diffusometry methodology and instrumentation currently available is routinely capable of quite fast multicomponent self‐diffusion mapping in solution, providing a quantitative pathway to many analytical applications as well as physicochemical information. A measurement time span of approximately 10 min may suffice, and an accuracy of a few percent or better is normally routinely achievable. Relating the behavior of self‐diffusion coefficients of solution components to, e.g. solution composition changes adds another dimension to the field and a path to quantitative methods for elucidation of, e.g. molecular association or conformational changes even in complex systems. In routine form, the techniques are primarily applicable to liquid systems and use proton ( 1 H) NMR detection. A limited number of nuclei other than protons (primarily 2 H, 7 Li, 13 C, 19 F, 31 P) are also amenable for monitoring. Electrophoretic NMR (eNMR) is a related, less exploited technique, which has a more limited applicability than NMR diffusometry, but which can be uniquely useful. Instrumental and methodological advances have lately also opened up the application field to proton‐detected diffusion studies in semisolid systems.

Chemiluminescence of phthalhydrazide derivatives in organized media: Interactions with surfactants and cyclodextrins

“…This technique relies on the changes in the NMR spin echoes [23] arising from a sample located in a magnetic field gradient as a result of translational molecular motions [24,25], rendering the self-diffusion coefficient (D) of a molecule in solution. Since D is sensitive to changes in molecular size, by comparing the diffusion coefficients in the absence and presence of surfactants [26][27][28] or CDs [29][30][31] the extent of binding to these macromolecules can be estimated.…”