Stable Isotope Geochemistry


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Gerard Olack <[log in to unmask]>
Reply To:
Stable Isotope Geochemistry <[log in to unmask]>
Wed, 18 Feb 2004 17:02:12 -0500
text/plain (72 lines)
HI Shuhei--

Yes, it's very confusing.  I randomly clicked my way through, which
meant it took a while for me to figure out what I did.  Anyway, for
Isodat 2.0, patch 1.35:

Setting amplifiers (no, they no longer show the amplifier setting next
to the mass, and you can't just flip between amplifiers from what I can
 From instrument control, go to the editors icon and select gas
configuration editor.  Highlight the gas of interest in the editor, e.g.
CO2, then right click on it.  A menu will pop up that has in it "Peak
Center--Basic Scan", "Resistor Channel 1--DioTransferPart", etc.
1.  If you select "Peak Center...", you can adjust the parameters to
widen the scan window for peak centering  in that gas mode--if they're
too narrow, you may not be able to see the peak when you peak center
during calibrations (hv scan settings 0 to 2500, 50 step--but I recall
seeing a release note indicating that you should increase the range).
2.  If you select "Resistor Channel 1...", that refers to cup 1, and a
dialog will appear for "ResisterCh0--State" and you can select "off"
(default) or "on" to pick the correct amplifier.  In our case mass 45,
cup 2, uses the second amplifier, so we choose "..Channel 2.." and the
dialog was for "ResisterCh1" (always one off), and we selected "on" then
save and close.

For the magnet setting for CO2 for a 253, try 5512.  I had trouble doing
calibrations in ver 1.5 when I tried to do a slow initial scan to get
"better" results, however the software just assumed I did a fast scan
and corrected the magnet settings accordingly, that is it over corrected
them--which meant it missed the peaks.  I did get Isodat2.0 to do a
correct calibration for me on a 253 with just the standard settings, and
I'm pretty sure that was with patch 1.35 (released in Jan).  Please
note, Isodat 2.0 patch 1.35 will "lose" your EE settings sometimes when
you reboot, which screws up your signal.

good luck


Shuhei Ono wrote:

>I am using MAT 253 with ISODAT NT2.0.  It seems like something happened
>with our gas configuration files.  First problem is that we lost a value
>for magnet for CO2, and I have been trying hard but cannot figure out
>how to do mass calibration to get things back.  It keeps missing the
>peak. It seems like I have to change the detection parameters but ISODAT
>manual is not very helpful with this.
>Second problem is that ISODAT switches to a wrong amplifier when I start
>analysis.  It just doesn't make much sense to me how to select the
>amplifier.  I'll appreciate if anyone can help me out.
>Any inputs will be greatly appreciated.
>Shuhei Ono
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>Geophysical Lab
>Carnegie Institution of Washington
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>Washington, DC, 20015-1305
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