5.6 Solid-State Cross-Polarization Magic-Angle Spinning
13
C Nuclear Magnetic Resonance Spectra
Solid-state cross-polarization magic-angle spinning
13 C nuclear magnetic resonance
(CPMAS
13 C NMR) spectra were recorded with a Fourier-transform (FT)-NMR
system (Alpha 300, JEOL Ltd., Tokyo, Japan). Approximately 100 mg of powdered
sample was transferred into KEL-F spinning tubes (6 mm diameter, JEOL Ltd.,
Tokyo, Japan). The solid-state CPMAS
13 C NMR signals were recorded at
75.45 MHz with 6 kHz of magic-angle spinning, 1 ms contact time, and a 3-s
pulse interval. A broadening factor of 100 Hz was employed in the Fourier transformation procedure. Standard chemical shift (0 ppm, tetramethylsilane) adjustment
was performed using adamantane (29.50 ppm) (Watanabe et al. 2007).
From the obtained solid-state CPMAS
13 C NMR spectrum for Myoko sclerotia
grains, the peaks of carboxylic and carbonyl C, aromatic C, O-alkyl C, methoxyl C,
and alkyl C were assigned. The spectrum showed that sclerotia grains contain a large
proportion of O-alkyl C, which indicated the dominance of sugar chains in sclerotia.
The methyl C detected in sclerotia grains was considered to originate from deoxy
sugars such as rhamnose (Watanabe et al. 2007).
5.7 Fourier-Transform Infrared Spectroscopy
Vibrational spectra of sclerotia grains were recorded over the 4000 to 200 cm
À1
wavenumber range using a Fourier-transform infrared spectrometer (FTIR-420,
JASCO Corp., Tokyo, Japan) equipped with a CsI beam splitter. About 0.1 mg of
Fig. 5.5 Major elements
(C, H, N, O), ash, and water
contents of sclerotia grains.
(Data source from Watanabe
et al. (2007))
5 Chemical Characterization of Sclerotia Grains Collected from a Volcanic Ash. . .
83