Dear Robert Van Hale,

I don't think Isodat is able to fit a sloping baseline. It just takes the
average of a certain number of points in front of the peak as background
value.
You can extract the raw data via the following procedure:
  # open the peak file you want to extract
  # store it under store as
  # toogle to *allfiles
  # name it something.ai

This will generate a text file containing the time column and your masses.
For instance: if you measuring CO_2, there will be four columns: time,
mass44, mass45, mass46
I don't think either, it might be a good idea to export it to MassLynx. I
don't know if it is even possible to change a .csv file into a file,
MassLynx can process. Also, I am not completely sure, if MassLynx can
perform a fir for a sloping baseline. The background and peak finding
procedure of MassLynx is not working that very well anyway.

I never heard of any program that was developed to calculate the isotopies
out of a raw data file except Isodat, MassLynx or any third MassSpec
seller.
You can use Matlab or a free alternative like Python, Octave, Fortran to
write your own processing program that is able to perform a fit of a
sloping background. This is not straightforward easy down, and such a
program is not developed overnight. For myself, it took me about 4 months
till I got a robust program. We developed a Matlab code based program for
CO_2 raw data processing. Including a slope fit of the background is
fairly easy. If you are interested, just call me off-list and I can sent
you a copy.


respect,

Robert Schneider

>
> Dear isotopers,
> I wonder if I am missing something, but is there no way to fit a sloping
> baseline for peak integration in Isodat? If that is the case then can the
> raw data be exported as text file or similar? Thirdly, can anyone suggest
> a favourite (free?) program that might perform this duty for me? (do you
> want me to import it to Masslynx?)
> Any suggestions or references to previous postings would be most welcome
> Thanks
> Robert Van Hale
>