Subject: Re: [nmr_sparky] Data heights
From: Mandar T. Naik
Date: May 30, 2006
Previous: 150
Hi Thomas,
Just to make this thread complete,
below is the relevant information from Brukers processing reference manual
:
NC_proc - intensity scaling factor
Processing in
XWIN-NMR performs calculations in double precision floating point but stores the
result in 32-bit integer values. During double to integer conversion, the data
are scaled up or down such that the highest intensity of the spectrum lies
between 2^28and 2^29. This means the 32 bit resolution is not entirely
used. This allows for the highest intensity to be increased, for example during
phase correction, without causing data overflow. NC_proc shows the amount of
scaling that was done, for example:
NC_proc = -3 : data were scaled up (multiplied by
2) three times
NC_proc = 4 : the data were scaled down (divided by 2) four
times
Although NC_proc is normally calculated by processing commands, 2D
processing also allows you to predefine the scaling factor with the argument
nc_proc, for example:
xfb nc_proc 2
**
NC_proc doesnt show up in the edp dialogue,
after processing it resides in the proc?s file and as Henry pointed, can be
visualized by dpp. It is not propagated by popular wpar/rpar method. I think
this is a potentiallyserious flaw for Xwin-Sparky combination in all
comparative quantitative work spread over two or more
experiments.
Best regards
-mandar
----- Original Message -----
From: Thomas
Goddard
To: nmr_sparky@yahoogroups.com
Sent: Wednesday, May 31, 2006
12:40 AM
Subject: Re: [nmr_sparky] Data heights
Hi
Mandar,
Sparky does not read the NC_proc Bruker parameter, so it
does not
apply that scaling to the data. So as Henry pointed out you
will need
to make sure the NC_proc is the same for the two spectra, or leave
the
spectra alone and scale your peak intensity ratios
appropriately.
It would be good if a future Sparky version took
proper account of
NC_proc.
Tom
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