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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