Very high-resolution H-1 MAS NMR of a natural polymeric material

The use of ultrafast magic angle spinning (> 30 kHz) in tandem with delayed echo acquisition is shown to yield very high-resolution H-1 MAS NMR spectr a of complex natural organic materials. For the first time, very high-resol ution H-1 MAS NMR spectra are reported for cork and wood components, two na tural materials with great economic importance. The effect of the spinning rate on the H-1 NMR spectra was evaluated with single-pulse acquisition and delayed-echo acquisition. The delayed-echo acquisition spectra presented l inewidths as sharp as 67 and 25 Hz. The narrow peaks, characterised by prot on spin-spin and spin-lattice relaxation, were assigned to the isotropic ch emical shifts and the general spectral features were shown to correlate wit h the sample chemical structure. The tentative assignments of cork H-1 MAS NMR signals were presented. (C) 1999 Elsevier Science B.V. All rights reser ved.