Hi Everyone - I wanted to report back to the group on this post and
especially thank the many people who responded. In particular, I wanted to
thank Alan Boyd, Ian Marshall, and Charlie Fry for their great insights into
the issue.
As it turns out, it seems very few labs out there are limiting 13C
acquisitions in any way other than via sign up rules and maximum slot
durations on walk-up instruments. Many of the respondents wrote to tell me
about the Bruker program au_zgsino, which I admit slipped my mind when I
sent in the original post. I did hear from several who use S/N checks to
limit 13C acquisition in an open access environment but as far as I can
tell, nobody is using the S/N from a preliminary 1H acquisition to set /
suggest a sensible number of transients for a given 13C acquisition
(although many like the idea)!
Currently, I am working on the latter approach but what I did over the past
week was redesign the Bruker au_zgsino program. It is now in operation on a
trial basis on our spectrometer to limit all 13C detected experiments based
on S/N checks. My apologies in advance to the Varian users for the
"Brukerese" that follows but I'll spell it out anyways in case you like the
ideas and can adapt them to your own installation. The design involves:
- ignoring solvent signal(s) when doing S/N checks by reading the region
files Bruker supplies in /exp/stan/nmr/lists/scl for peak picking scaling.
This avoids the need to have many different solvent-specific parameter sets.
- For every block of scans, an entry is made in the experiment title file
showing the user how the S/N is building up.
- If the experiment is cut short based on the S/N threshold being reached, I
again make an entry in the experiment title file suggesting to the user that
although he/she submiited a gazillion scans, x number of scans appears to be
adequate.
- lastly, for every experiment that gets cut short, I append an entry into a
master file so that I can keep an eye of things, who the most frequent
"abusers" are, the number of scans requested, and the number of scans that
actually completed.
Although I am not using it, I put the infrastructure in place to use this
program for 1H acquisitions also (since Bruker supplies the region files
anyways). I'd be only too happy to send a copy of the program to other
facility managers who are interested in trying it out. Although I am using
it on a TopSpin 2.1.1 installation, the program at least compiled without
error on a TS 1.3.6 datastation as well as an xwin 3.5 datastation.
Send me a quick email if you're interested in a copy.
Cheers,
Mike
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Michael D. Lumsden, Ph.D.
NMR Facility Coordinator
Room 428, Atlantic Region Magnetic Resonance Centre
Department of Chemistry, Dalhousie University
6274 Coburg Road
Halifax, Nova Scotia, Canada
B3H 4J3
phone: 902-494-1635
FAX: 902-494-1310
http://armrc.chemistry.dal.ca
Received on Thu Sep 04 2008 - 04:47:18 MST