Sample concentrations and purities can be easily measured from known peaks once the proportionality constant is calibrated using a reference of known concentration. In other words, the peaks are a chemical signature and the sample concentration is proportional to the intensity of the NMR signal detected. The peaks in the spectrum will appear in predictable locations in the spectrum and their intensities will be proportional to the number of nuclei in the sample.
These same properties result in NMR being excellent for quantification and identification. This is because the electronic structure, the bedrock of chemistry, is what determines the chemical shift, while the number of nuclei determine the coupling and relative intensities. The chemical structure of a small molecule dictates a rational spectrum. NMR is best known for its use in structure determination. Identification, Quantification (qNMR) and Mixture Analysis
