Tom,
Another potential option that might work well is to use the simple processing
macro cryoproc1d, which is supplied by Bruker in the au program library. While
this macro is intended for use with cryoprobes to eliminate baseline distortions
from probe ringdown, it may well work for your background signal issue. We have
used it on thousands of 19F and 13C spectra with excellent results. I have
attached the macro and also put the header in this message in case the attachment
doesn't come through. It is also in your standard Bruker au library. The one I
show you here is from an AVANCE II with TS 3.2Pl7 but it is in all versions as
far as I know. The header, shown below, gives a tutorial on how to set up this
macro. It is easy to do. In your case, set DE and RDpoints until your baseline
is flat after running the processing macro and save the parameter set with these
values. It is likely that the optimal values you find for DE and RDpoints will
not be tremendously different from the default values, but you should calibrate
it. DE will need to be longer than the default value. Once calibrated, save it
in your user au program lib under a new name and use it to process your data.
Note that it will work in automation by setting the aunmp parameter to the name
of the macro. Possible advantages to using this over other methods:
1.
No special pulse programs are needed. It works with any 1D pulse program which
shows the distorted baseline.
2.
The original data is preserved as this is only a processing macro.
3.
Since it uses the widely accepted and tested technique of back linear prediction to
restore data points from the fast relaxing background signal, the resulting data
has the fidelity of any data processed with linear prediction, which is routinely used in NMR.
Nothing I have said here is meant to imply that this method is the best one. I
suggest it for the reasons I mentioned. I imagine it could work in your case.
Good luck,
Greg
Gregory J. Heffron | Director, Biomolecular NMR Facility | Visiting Scienti=
st, Dana-Farber Cancer Institute | Department of Cancer Biology
Harvard Medical School | 240 Longwood Ave. | Boston, MA 02115 | Tel: 617-33=
5-2929|
/***********************************************-*-C++-*-********/
/* cryoproc1d 21.12.2011 */
/****************************************************************/
/* Short Description : */
/* AU program to process cryo probe X-nuclei spectra with */
/* removal of ringdown by linear back-prediction. */
/****************************************************************/
/* Keywords : */
/* 13C, C13, X, ringdown, deadtime */
/****************************************************************/
/* Description/Usage : */
/* This AU program processes X spectra acquired with a cryo- */
/* probe. Due to the high Q of a cryoprobe, there is a */
/* significant ringdown time of the coil and the beginning of */
/* the FID is distorted. The AU program replaces these */
/* distorted data points by back-predicted ones. It uses */
/* reasonable defaults for DE and "rdpoints". */
/* It is recommended that those values are measured once for */
/* each probe. DE should have a value, where RG is no longer */
/* degraded by the ringdown, i.e. increase DE as long as RGA */
/* finds bigger values. */
/* The AU program modifies the FID, therefore the original FID */
/* is saved to expno+100000. After runinning this AU program */
/* the raw data can be reprocessed by normal 'efp'. */
/* The number of points (!! complex number) to be back- */
/* predicted may be given on the command line. */
/****************************************************************/
/* Author(s) : */
/* Name : Rainer Kerssebaum */
/* Organisation : Bruker BioSpin GmbH */
/* Email : Rainer.Kerssebaum_at_bruker.com */
/****************************************************************/
/* Name Date Modification: */
/* rke 111220 c13cryo extended for other X-nuclei */
/* rke 150511 info written to audit files */
/****************************************************************/
/*
$Id: cryoproc1d,v 1.1.2.2 2015/05/11 14:27:43 wem Exp $
Gregory J. Heffron | Director, Biomolecular NMR Facility | Visiting Scienti=
st, Dana-Farber Cancer Institute | Department of Cancer Biology
Harvard Medical School 240 Longwood Ave. | Boston, MA 02115 | Fax :617-432=
-4383
> From: main_at_ammrl.groups.io <main_at_ammrl.groups.io> on behalf of Tom Pratum via groups.io
> Sent: 10 January 2024 23:24
> To: main_at_ammrl.groups.io <main_at_ammrl.groups.io>
> Subject: [AMMRL] 27Al background signal in iProbe
Hello All-
We have a fairly new 400 MHz NEO Nano instrument with a broadband iProbe. One
user is very interested in 27Al, and I note that in this probe there is a
relatively significant 27Al background signal - I have seen 27Al background
signals in pretty much every probe I have ever looked at. I have attached
a plot of the signal (tuned empty probe) as acquired with a 2 usec pulse
(around a 30 degree pulse at this power level), with the sw maxed out at 1.875 MHz,
and 8 scans. The central component is around 11 kHz wide.
I find the background signal relatively surprising due to the large number
of components, and I am thinking the appearance could possible be due to one
or more spin 5/2 powder patterns in which only the narrowest components appear
due to how the spectrum was acquired, but really don’t know if that is the
case. These components are not artifacts as they do move with the field.
The user has some pretty broad signals they are interested in quantitating,
and it would be good to remove the central component of this background signal
if possible. I can think of a number of characteristics - such as T2 and rf
inhomogeneity - that could be used to remove the signal, but they would also
likely affect the quantitation to some degree,
Does anyone have any experience in removing this background signal they can
suggest?
Thanks in advance.
Tom Pratum,
Southern Oregon University
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Received on Thu Jan 11 2024 - 07:09:19 MST