Quantitative NMR in synthetic and combinatorial chemistry.

The applications of quantitative NMR to synthetic organic chemistry are reviewed with taking into account both the small libraries (100-150 compounds) and the single, well-characterized substance. The precision and accuracy which are obtained with state of the art instrumentation--both around 1%--rival with other classical tools of quantitative analytics, and qNMR does not require a specific method setup or a standard of the same substance. This characteristic makes it the method of choice in an environment where many different molecules are investigated and reliable quantification is required. NMR may effectively replace other standard characterization tools, such as CHNS analysis, or even complex, multi-determination results as commonly required for the assessment of absolute purity or strength of a substance, when no specific standard is available. Finally, because of the high precision and intrinsic accuracy, quantitative NMR appears the ideal reference method for the validation of other, more rapid, generic techniques for quantitative analysis.