Quantitative determination:

Different protons present in a sample come to resonance at different frequencies depending on their chemical nature. The shift in the frequency of a given proton with respect to an internal standard is called chemical shift and is measured in terms of a dimensionless parameter called δ or ppm. The chemical shift position of a proton depends on a number of factors like the electronegativity of the attached groups; the anisotropy of the bond, hydrogen bonding, etc. The signal for a given kind of proton is split into a number of lines. The number of lines and their intensity ratios depend on the number of equivalent neighbouring protons. This is called spin-spin coupling and the magnitude of the splitting called coupling constant is a measure of the energy of interaction between the protons.

The NMR spectroscopy is very widely and routinely used for the identification and structure elucidation of organic, organometallic and biological molecules. However, very few attempts have been made for quantitative determination of absorbing species also. Some of the quantitative applications of NMR spectroscopy are: analysis of multi-component mixtures, elemental analysis and organic functional group analysis.