Nuclear magnetic resonance spectroscopy experimental methods

In the case of heterogeneous polymers the experimental methods need to be refined. In order to analyze those polymers it is necessary to determine a set of functions / (M), which describe the distribution for each kind of heterogeneity i This could be the mass distributions of the blocks in a diblock copolymer. The standard SEC methods fail here and one needs to refine the method, e.g., by performing liquid chromatography at the critical point of adsorption [59] or combine SEC with methods, which are, for instance, sensitive to the chemical structure, e.g., high-pressure liquid chromatography (HPLC), infrared (IR), or nuclear magnetic resonance spectroscopy (NMR) [57],... 

Lambert, J.B., Holland, L.N., and Mazzola, E.P., Nuclear Magnetic Resonance Spectroscopy Introduction to Principles, Applications and Experimental Methods, Prentice Hall, Englewood Cliffs, NJ, 2003. 

Experimental Structural Methods 2.05.3.1 Nuclear Magnetic Resonance Spectroscopy... 

The following entry defines the commonly used stability constants (stepwise, overall, conditional, association, dissociation, and pK) and relates the values to a rigorous thermodynamic definition of equilibrium constants. In addition, the article briefly outlines experimental techniques (potentiometric titration, spectroscopic methods involving ultraviolet/visible, infrared, Raman, fluorescence. and nuclear magnetic resonance spectroscopy), together with the numerical methods and computer programs that can be used to derive stability constants from such experimental data. 

After purification, quality control of solvent purity is necessary. For this purpose, many different analytical methods are utilized. Generally, chromatographic methods such as GC, GC-MS, and HPLC are used. Moreover, UV, infrared, and nuclear magnetic resonance spectroscopy can also be applied but they tend to be less sensitive toward trace impurities. Water in organic solvents is usually determined by Karl-Fisher titration. On the basis of experimental data obtained before and after purification, the efficiency of the clean-up procedure is determined. In general, the efficiency of purification, e.g., the recovery, is expressed by the coefficient R. This parameter is defined as the ratio of the amount of impurities removed to the amount of solvent before purification ... 

Discussed in books on nuclear magnetic resonance spectroscopy, for example, J. B. Lambert and E. P. Mazzola, Nuclear Magnetic Resonance Spectroscopy. An Introduction to Principles, Applications, and Experimental Methods, Pearson Education, Upper Saddle River, NJ, 2004. 

It is possible to examine experimentally both the diffusion in a liquid crystal of its own molecules (self-diffusion) and the diffusion of impurities. The coefficients of self-diffusion are determined by various methods, e.g., quasi-elastic neutron scattering [100], the diffusion of tracer (radioactive) molecules [101], or the spin-echo methods in nuclear magnetic resonance spectroscopy [102]. The last method is probably the most reliable. Essentially, it is as follows initially the spins of the molecular protons are polarized by a marked pulse of a radio-frequency field then the molecules... 

---