th  - 1988 - 51st ENC Conference

15 II9F CRAMPS OF INORGANIC FLUORIDE COMPOUNDS:
*Karen Ann Smith and Douglas P. Burum , Colgate-Palmolive, 909 River Road,
Piscataway, NJ 08854, and Bruker Instruments, Inc., Manning Park, Billerica,
MAOI821.
The major mineral component of human dental enamel is hydroxyapatite.
Fluoride treatment of apatite can result in formation of calcium fluoride
and/or fluoroapatlte, depending on treatment conditions. In addition,
dentifrices may contain various sodium or potassium salts which could result
in a variety of fluoride-contalnlng compounds precipitating or forming. Many
of these compounds have large fluorlne-fluorlne dipolar couplings, which
broaden the spectra and ma~ resolution of individual resonances difficult
with MASS alone. However F CRAMPS allows identification and resolution of
calcium fluoride, fluoroapatite, sodium and potassium fluoride, and sodium
and potassium monofluorophosphate, even when all are present simultaneously.
Fluorine-19 has a large chemical shift range, which can be a problem in using
multl-pulse techniques. Here, quad detection (achieved by data sampling in
all 4 2~wlndows in the MRev-8 cycle and appropriate data manipulation) was
used to double the effective sweep width of the multiple pulse sequence, and
cover the range of chemical shifts needed.
Spectra taken with 19F CRAMPS, as well as details of the pulse sequence and
data handling used will be presented.
16 I 13C NMR RELAXATION STUDIES OF GLUCONATE AND MANGANESE-GLUCONATE
INTERACTIONS, W. Robert Carper* and David B. Coffin, Department of Chemistry, Wichita
State University, Wichita, KS 67208.
13
The effect of temperature on the spin-lattice (R I) and spin-spin (Rp) C relaxa-
tion rates of gluconate and manganese(II)-gluconate solutions is determined in D~O.
We observe a R~ vs. temperature minimum for gluconate solutions similar to that ~b-
served in solia-liquid phase transitions. Nuclear Overhauser enhancement factors
indicate predominately dipolar relaxation mechanisms for all except the carbonyl
carbon. Activation energies and chemical shifts indicate a molecular reorientation
involving the carbonyl carbon which results in changes in solvation (hydrogen bond-
ing) effects. Addition of manganese(II) to gluconate in D~O results in an observed
temperature minimum in R 1 vs. reciprocal temperature plots for all except the carbonyl
carbon atom. Activation energies further support the concept of changes in solvent-
manganese-gluconate interactions affected by a change in intra-molecular structure.
This work has been supported by a grant from NIDDKD (DK 38853).
105