A limitation of 13C CP-MAS n.m.r. spectroscopy for the study of treated coals

Abstract Carbon-13 n.m.r. spectroscopy is often considered to be a quantitative method for analysis of coals and treated coals provided the experimental conditions are carefully selected. In some cases, the magnetic impurities strongly affect the spectra leading to non-quantitative measurements and even to the impossibility of observing a spectrum.