th  - 1988 - 51st ENC Conference

To be presented at the 29th Experimental Nuclear Magnetic Resonance Spectroscop~
Conference, April I?-21, 1988 at Rochester, New York.
1 84 I MULTINUCLEAR N-MR METHODOLOGY FOR DECONVOLUTING NATURAL
MIXTURES AND CATALYTICALLY ACTIVE LAYER SILICATESt: Arthur R. Thompson*,
Kathleen A. Carrado and Robert E. Botto, Chemistry Division, Argonne National
Laboratory, 9700 South Cass Avenue, Argonne, IL 60439
The combined use of a variety of pulse sequences and variable field has expanded
the utility of solid-state aluminum-27 and silicon-29 NMR of layer silicates.
The goal of this research has been to improve our knowledge of the possible roles
of layer silicates in coal formation and catalysis. Many natural systems such as
coal contain a mixture of layer silicates and their similar structures coupled
with a lack of uniformity within a clay often yield broad overlapping spectra.
Therefore, we analyzed several clays and their chemically modified variants to
determine how to selectively distinguish that particular layer silicate. Some
layer silicates when chemically modified to increase their catalytic activity
show radical changes in their NMR spectra while others show remarkably little
change. We have used these selective methods to determine which layer silicates
present are more intimately associated with the organic portion of coal, and
hence more likely to have played a role in coaliflcati0n. We feel these results
demonstrate the feasibility of using NMR spectroscopy to study complex systems of
layer silicates.
tWork performed under the auspices
Division of Chemical Sciences, U.
number W-31-109-ENG-38.
of the Office of Basic Energy Sciences,
S. Department of Energy, under contract
PARSING THE EDITED 1H NMR SIGNALS INTOI2c-1H ANDI3C-IH SUBSPECYRA:
185 I ASTRATEGYTO STUDY SPECIFIC A£TIVITY IN VIVO.
T. Jue*
Dept. Molecular Biophysics and Biochemistry, Yale University, ~wHaven, Ct. 06511
The general concern with the indirect detection experiment is sensitivity
enhancement; a particular requirement of an in vivD experiment is specific activity.
Tracing the metabolic flux entails an isotopic precursor infusion and a subsequent
product analysis. However, the product is diluted by fluxes through the many path-
ways, start'.~ng with endogenous, unlabeled precursors.
With 13C isotope strategy both the 12C-IH and 13C-I~ si~%als are neoessary
to access fractional enrichment information. St~m~dard [ C[-'H heteronuclear
editing sequence (i) does not always yield the 12C-IH signal, being often masked
by the background lipid reson~ces. Howe~. homonuclear editing sequences will
select sinultaneously the 12C- H and 13C- H resonances (2).
Because in vivo experiments are conducted at lower field, ~e have refined
the editing strategy to separate the edited 12C-IH and 13C-IH signals into sub-
spectra. This strategy permits us to decouple and to impl~t the fractional
.enrichment study at lower field.
i. M. R. Bendall, D. T. Pegg, D. M. Doddrell, and J. Field J. Am. Qhem. Soc. 103,
934, 1981.; R. Freeman, T. H. ~reci, G. A. Morris J. Magn. Neson. 42, 341, 1981.
2. T. Jue J. Magn. Reson. 73, 524, 1987.
191