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High resolution MAS provides an easy means of obtaining high resolution spectra of a variety of samples that would otherwise result in poorly resolved spectra, due to residual anisotropic interactions. The addition of a HR-MAS probe and a MAS pneumatic unit to a standard high resolution spectrometer is all that is needed to open a gate to the world of HR-MAS spectroscopy and access to a vast amount of highly interesting samples. In this section a number of application examples are shown from a variety of compounds. All spectra are acquired with standard high resolution techniques. HRMAS of small organic molecules There is a wide variety of conceivable applications for HR-MAS probes. Among others, one important field for pharmaceutical research concerns combinatorial chemistry. In combinatorial chemistry, small organic molecules are synthesized on resin beads, consisting of a polymer matrix and a linker material. NMR is advantageous in analyzing these samples since the reactions can be monitored without cleaving off the substrate. High resolution NMR spectra are obtained by swelling the beads in a deuterated solvent in combination with Magic Angle Spinning.
obtained with a single pulse (top) and with a CPMG sequence (bottom). The resonances the resin in the lower spectrum, by employing a CPMG sequence with =1.5 ms and n=20. Avance 400 MHz, 3200 Hz spinning, 2 mg sample on Tentagel substrate, swollen in deuterated chloroform. Spectrum from Bruker user's menu.
HRMAS of biological samples Plant, tissue and food samples can be investigated by HR-MAS NMR. The usefulness of magic angle spinning within these fields of study is demonstrated in the examples shown below.
8 mg red perch filet, cut, flushed and measured in D 2O.
HRMAS of benign versus malignant human prostate tissue
TOCSY-presat of a living white worm (enchytraed) in 95% H2O/5% D2O. Spectrum is from Bruker user menu.
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Photo by Shaoxiong Wu, Lake Taheo, CA, October, 2003
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