Solid-State Nuclear Magnetic Resonance Spectrometry

SOLID-STATE NUCLEAR MAGNETIC RESONANCE (SS-NMR) SPECTROMETRY 

Even though pharmaceutical applications of solid-state NMR (SS-NMR) are well documented, the full potential of this technique has not yet been realized, and it is anticipated that solid-state NMR will become a standard technique for characterization of pharmaceutical solids. 

In contrast to proton spectroscopy in solutions, 1H-NMR has found only limited application in the solid state, mainly because of the existence of extensive line broadening originating from strong through-space, dipole-dipole coupling. This interaction is completely averaged out in solution as the molecules rapidly tumble on the NMR time scale. In solids, however, molecules are locked in their crystal lattices. In the absence of extensive molecular motions, the dipole-dipole interaction can be very strong and are 

FIGURE 5 Solid-state proton spectra of (L)-alanine, showing the differences between spectra acquired in static, spinning, and CRAMPS modes. All 500 MHz spectra were acquired at ambient conditions. 

The CRAMPS experiment puts a large demand on the NMR hardware (especially on NMR probes), since high-power radio frequency (rf) pulses are applied between each acquisition point. High homogeneity of the irradiation field, as well as careful setup of experimental variables, is required to avoid distortions of the proton peaks. Typical line widths afforded by the CRAMPS experiment are approximately 1 ppm, limiting the application of the CRAMPS experiment to compounds with a small number of well-resolved protons. 

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Raman Spectrum C Solid-State Nuclear Magnetic Resonance Spectrometry... 

Vassallo, A.M., Wilson, M.A., Collin, P.J., Oades, J.M., Waters, A.G., and Malcolm, R.L. Structural analysis of geochemical samples by solid-state nuclear magnetic resonance spectrometry. Role of paramagnetic material. 1987 59 558-562. 

Medek, A. Solid-state nuclear magnetic resonance spectrometry. In Spectroscopy of Pharmaceutical Solids, (H. G. Brittain, ed.), Taylor 8c Francis, New York, 2006. Chapter 11. 

For the further study of the structural heterogeneity of lignin, mild and selective cleavage of bonds, pyrolysis gas chromatography-mass spectrometry (GC-MS), and solid state nuclear magnetic resonance are particularly important. 

Further information about the nature of the bonded phase can be obtained through solid-state nuclear magnetic resonance and infrared spectrometry. These techniques allow us to obtain semiquantitative information about the distribution of the different types of silanols on the surface on both the parent silica and the bonded phase. Since it has become understood that metal contamination in the matrix of the silica can significantly influence the activity of silanols on the silica suifrux, the examination of a silica for trace-metal content can be very cnli tening. A low content (<10ppb) of especially aluminum and iron is desirable. 

Gerstein BC, Dybowski CR (1985) Transient techniques in NMR of solids an introduction to theory and practice Academic Press, Orlando, 295 pp Hatcher PG (1987) Chemical structural studies of natural lignin by dipolar dephased solid-state nC nuclear magnetic resonance Org Geochem 11 31-39 Hatfield GR, Maciel GE, Erbatur O, Erbatur G (1987) Qualitative and quantitative analysis of solid lignin samples by carbon-13 nuclear magnetic resonance spectrometry Anal Chem 59 172-179... 

An illustration in PR shows, as a small icon of spectroscopic progress, the improvement in sensitivity of nuclear magnetic resonance spectrometry. In only 15 years, the solid-state 13C spectrum of adaman-tane, with only two types of carbons, CH and CH2, had turned from inaccessibility to an easy routine. Such solid-state 13C spectra became important diagnostic tools for the chemical industry in the areas of polymers, whether as elastomers, textile fibers, or plastics such as polypropylene. 

See also Chromatography Overview. Liquid Chromatography Instrumentation Liquid Chromatography-Nuclear Magnetic Resonance Spectrometry. Nuciear Magnetic Resonance Spectroscopy Techniques Principles Multidimensional Proton Solid-State In Vivo Spectroscopy Using Localization Techniques. 

See also Extraction Solid-Phase Extraction. Food and Nutritional Analysis Oils and Fats Fruits and Fruit Products. Lab-on-a-Chip Technologies. Liquid Chromatography Liquid Chromatography-Nuclear Magnetic Resonance Spectrometry. Nuclear Magnetic Resonance Spectroscopy Oven/iew Principles Instrumentation. Nuclear Magnetic Resonance Spectroscopy Applications Food. Nuclear Magnetic Resonance Spectroscopy Techniques Solid-State. Peptides. Radiochemical Methods Radiotracers Pharmaceutical Applications. 

Zhang, M., and Maciel, G.E. Built-in carbon-13 intensity reference for solid-state analysis by magic-angle-spinning nuclear magnetic resonance spectrometry,... 

Several physical methods have been employed to ascertain the existence and nature of ICs infrared (IR) absorption spectroscopy nuclear magnetic resonance (NMR) spectroscopy,14 including JH nuclear Overhauser effect (NOE) difference spectroscopy, H 2-D rotating-frame Overhauser effect spectroscopy (2-D ROESY),15 and solid-state 13C cross-polarization/magic angle spinning (CP/MAS) spectroscopy 16 induced circular dichroism (ICD) absorption spectroscopy 17 powder and singlecrystal X-ray diffraction 18 and fast atom bombardment mass spectrometry (FAB MS). 

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