Background signal in solid state 13C NMR spectra of soil organic matter (SOM)-quantification and minimization.
13C background signal, obtained for an empty rotor, was shown by spin counting experiments to be equivalent to 1 mg of observable carbon for cross-polarization (CP) spectra and 69 mg of observable C for Bloch decay (BD) spectra. The BD background was mainly due to Kel-F in the stator. with minimal signal detected from the Kel-F end-caps. The CP background was attributed to non-Kel-F components of the stator, probe, or probe supports. The BD background signal was eliminated by using a modified dipolar dephasing pulse sequence in which the absence of 19F decoupling (rather than the absence of 1H decoupling) causes selective elimination of the Kel-F signal.
Smernik
R J
RJ
Department of Soil and Water, Waite Agricultural Research Institute, University of Adelaide, Glen Osmond, South Australia, Australia. ronald.smernik@adelaide.edu.au
Oades
J M
JM
D002247:Carbon Isotopes; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D012987:Soil / Q000032:analysis*
D002247:Carbon Isotopes; D012987:Soil