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
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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