Paul, 
    Thanks.  That's a great simple solution to save a minute .  However, I'm
most interested in speeding up my analysis of N20 (see Casciotti et al.
2002), where the headspace is loaded onto a cryo-trap for 13.3 minutes
before the valco valve switches into inject.  Another ~12 minutes remains
for the N20 to get a second cryo-focusing, separate on the GC column and
come back to baseline.  Nearly this entire time could be used for loading
the next sample.  Anyone have ideas on how to do this?
 
Anthony


  _____  

From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf
Of Paul Brooks
Sent: Wednesday, September 05, 2007 4:03 PM
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] IsoDat script to advance autosampler while
aquiring peak tail data


Anthony,

We were able to save almost all the time of flushing the sample by simply
getting the auto sampler to move the needle into the sample tube at the
beginning of each line of the sequence, and then peak centering.  Since peak
centering takes about 60-70 seconds we saved a minute a sample.  Since we
routinely run 96 or more tubes per day, this saved over 1.5 hours per
sequence.

We simply swapped the position of the first two subroutines in the
"aquisition.isl" script.  The first now goes tells the sampler to move, the
second tells the mass spectrometer to peak center.

If you are interested contact me directly and I can send you a copy of our
ISL file.

Paul Brooks.



At 12:23 PM 9/5/2007, you wrote:


I'm trying to speed up some of my slower methods on the GasBench.  The last
and biggest target for trimming is the time it takes for the GC PAL
autosampler needle to advance to the next sample and flush the injection
loop.  If I could advance the needle to the next sample immediately after
the last sample loop injection switching and while the IRMS is still
aquiring data, it would be possible to save several minutes per sample, and
several hours per rack of samples (22+ hour runs are not convenient for
reloading).  Has anyone figured out how to do this?
 
I have a few ideas on how it might be done.  Clicking on a cell in the
Switch Methods column of the Time Events table in the methods file brings up
a dialog box with the option to initiate a "post script."  My thought is
that I could modify the Aquisition script to omit "call UploadSamplerMethod"
at the begining of running a sequence line, then start a script at a
specific time in the Time Events table to "UploadSamplerMethod" and initiate
advancing the needle to the next sample.  Two potential pitfalls are that 1)
I have no experience with ISL and wouldn't know exactly how to modify these
scripts other than by trial and error, and 2) my observation is that for
IsoDat to start the next line in the sequence the PAL needs to complete its
method and the needle needs to be "parked at home".
 
Any thoughts or scripts to send my way would be greatly appreciated.
 
Cheers,
Anthony
 
_____________________________________________________________________
Anthony K. Aufdenkampe, Ph.D.
Assistant Research Scientist - Isotope & Organic Geochemistry
Stroud Water Research Center
970 Spencer Road
Avondale, PA 19311
Tel:  610-268-2153 ext. 263
Fax   610-268-0490
http://www.stroudcenter.org/about/aufdenkampe.htm
 

Center for Stable Isotope Biogeochemistry
Valley Life Science Building Room 3060
Integrative Biology - MC3140
Berkeley CA-94720
Phone: (510)-643-1748
Fax: (510)-643-1749
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