Bruce,
I am sorry to send this message so late, but I have just red your e-mail
recently.
Bill is right, you have to hook up an other computer to run the CE
software simultaneously.  We are doing that all the time.  However, the
two softwares do not communicate to each other, therefore to set the
analysis time (not the same as acquisition time in ISODAT) in the two
softwares is critical.  Additionally, the time period for Jump to
....and peak center in the ISODAT is not necessarily the same at every
analysis.  So, to synchronize the two softwares is a meter of playing,
and trying.  We managed to get the first 15-20 analysis synchronized out
of 50 samples.

However, we could get very good concentration measurements through the
MS. The variation is within 1% generally.  What we do, we condition the
column with 3-5 referents material, (acetanilide), and name the last one
as Ref.  Additionally, we dry and weigh our samples very carefully.  I
suggest plot weight (mg ) and Amplitude (Volt) from your result
spreadsheet, before you try anything major.  The relationship should be
linear, if not  you have a weighing problem either because your samples
are not dried enough, or your balance is not good.



Bill Showers wrote:
>
> Bruce,
>
> You need to run the CE software at the same time with the isodat, you need
> another computer hooked up to the CE and turn on the filament on the CE.
>
> Buying the software from CE is pretty expensive, Bruno at COSTECH may be
> able to get you a used lower version (DOS) copy for a lower price.
>
> Bill Showers
>
> >Dear List,
> >
> >Our new Delta XL is starting to give reliable 13C and 15N numbers on
> >combusted leaf samples, but the elemental percentages (especially for
> >carbon) are still pretty bad (values of replicate samples range from 42 to
> >55% C; known %C is 45%).
> >
> >I'm wondering if the TCD might be more accurate, and if anyone has been
> >able to use the TCD on the Carlo-Erba EA while running Isodat.  I suppose
> >this could be done by running a separate computer with the CE software,
> >letting the CE software start the EA, and setting the timing just right so
> >that Isodat and the CE software are in sync.  There may be other ways.  Any
> >advice?
> >
> >Thanks.
> >
> >Bruce Hungate
> >
> >
> >
> >*******************************
> >Bruce Hungate
> >Assistant Professor
> >Dept. of Biological Sciences
> >Box 5640
> >Northern Arizona University
> >Flagstaff AZ 86011-5640
> >
> >phone:  520 523 0925
> >fax:    520 523 7500
> >email:  [log in to unmask]
> >*******************************
>
> -------------------------------------
> Dr. William J. Showers
> Director,  NCSU Stable Isotope Lab
>
> Dept of Marine Earth & Atm. Sciences,
> North Carolina State Univ.
>
> [log in to unmask]
> (919) 515-7143 - Voice
> (919) 515-7802 - FAX
>
> Common sense is genius dressed in working clothes. (Emerson)