Humic soil and coal structure study with magic-angle spinning 13C CP-NMR

In our recent report on using the 13 C cross-polarization (CP) NMR technique to characterize the organic matter in whole soils 1 , we discussed the limitations of the technique in terms of resolution and the improvements possible using ‘magic-angle’ sample spinning (MAS). We now report experiments on a soil and a brown coal in which these techniques have been combined. The spectra provide information on the chemical structure of the materials and throw new light on the nature of the various types of carbon in coals and humic materials.