th  - 1988 - 51st ENC Conference

S
Pascale Sole*, a b
Frank Delaglio, a'
George C. Levy, b
I
CONSTRAINED DECONVOLUTION OF 2D NMR SPECTRA AND IMAGES
a
b New Methods Research, Inc., 719 E. Genesee Street, Syracuse, NY 13210
Syracuse University, Department of Chemistry, Syracuse, NY 13210
We have been examining a fast constrained deconvolution method used to
achieve better resolution in 2D spectra and images. The method uses
estimates of the noise mean and variance in conjunction with a
criterion of spectral quality to reconstruct the 'best' result. The
quality criterion is a smoothness constraint, such as the minimization
of the second derivative amplitude or a maximization of the entropy of
the spectrum. Both approaches are illustrated and compared.
We show that the use of a Taylor approximation in the derivation of
the maximum entropy deconvolution filter allows an implementation much
faster than conventional iterative techniques. The measured spectrum
is modeled as the sum of a 2D random noise process and an ideal
spectrum convolved with a generalized point spread function. Spectral
lineshape parameters can be used to choose an appropriate point spread
function. Once this convolution function is chosen, the
resolutlon-enhanced spectrum can be rapidly reconstructed using the
approximate form of the entropy in an iterative Newton-Raphson scheme.--
..
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AUTOMATED HI ~E~I'kA MADE ON AN XL-300: George S!omp. The Upjohn
. . .
Company, Kalamazoo, MI 49001
An automated program for preparing routine IH spectra is described. The progra~
can run unattended saving much operator time, makes uniform spectra, and ~jnimizes
human error. The program employs three levels of easily-modified MAGICAL "m macros and
features"
I. A wide variety of solvents are known and the program corrects for the
ambiguous d7-DMF lock.
2. Prompts ask for a title and other identification if desired.
3. Escape is offered at potential trouble spots and resume is provided if manual
interaction was taken.
4. Current activity is always displayed.
5. Output is identified with title, date, event time, method of referencing,
ignored intense peaks and broad downfield lines.
6. The f.i.d, is saved on a floppy.
Spectra are referenced to ~.IS, solvent, or by default and then they are scaled
vertically ignoring solvent, TMS, and unimportant intense lines. Threshold for the
line list is offered at 3X noise level or if ignored it will iterate to a maximum of
88 lines, or less for small molecules. The spectrum, integral, parameters, title, and
other information are plotted on II x 17 blank paper using an HP7550 at a standard
width of IOPPM. Broad downfield peaks are inset at left of plot.
Potential troubles and their remedy will be illustrated.
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