Page 385 - Academic Press Encyclopedia of Physical Science and Technology 3rd Analytical Chemistry

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Encyclopedia of Physical Science and Technology EN0011A-541 July 25, 2001 17:27

488 Organic Chemistry, Compound Detection

FIGURE 12 1 H NMR spectrum (300 MHz) of (±) cis-δ-lactone in CDCl 3 .

A routine sample on a 60-MHz instrument would re- in the works, including a 900-MHz and gigahertz instru-
quire about 5–50 mg of the sample in about 0.4 mL sol- ments being built in the United Kingdom, United States,
vent. A microtube consisting of a thick-wall capillary al- Germany, and Japan.
lows spectra to be obtained on less than 1 mg of sample. Thenewinstrumentswillfindcuresfordiseases,resolve
The use of FTNMR makes it possible to obtain spectra the molecular structures of protein, amorphous polymers,
on amounts as small as 5 µg. The ideal solvent should ceramics, and biomaterials, and elucidate the dynamics of
contain no protons in its structure, be low-boiling point, biological systems.
nonpolar, and inert. Carbon tetrachloride is often used in High-resolution NMR may serve as an ideal compli-
non-FTNMR spectroscopy, depending if the sample is suf- ment to X-ray crystallography because it provides infor-
ficiently soluble in it. The most widely used solvent is mation on molecular dynamics that crystals, being static,
deuterated chloroform (CDCl 3 ). cannot. NMR enables observation of changes in the dy-
namics of a protein when it binds to DNA, or details the
relationship between catalytic function and motion. This
I. Nuclear Magnetic Resonance (NMR)
information would be useful in drug design.
New health and materials sciences for societal needs will Stoking the interest in faster access to protein structure
both fuel the drive to make high-field NMR spectroscopy are the rapid advances in genome research that are spewing
a more accessible research tool. Currently, only a hand- out genes with no known function.
ful of the most powerful 800-MHz NMR spectrometers A Swiss NMR technique makes it possible to obtain
and no more than a dozen 750-MHz instruments are in high-resolution solution NMR spectra of macromolecules
use in the United States. More powerful instruments are and supramolecular structures with masses up to several