Chromeleon 6.8 integrating fixed time range

[bunnahabhain]

Hi everybody

I'd like to tell chromeleon to integrate from 1.3 min to 3.0 min, irrespective if there is a small, large, noisy peak or just background noise.
Why? I am doing direct injection to ESI-MS without chromatographic separation. So I get very different peak sizes (including widthfrom 0.5 to 1.5 min) which are noisy, additionally. I did not find a way so far to set the sensitivity, peak slice, min/max peak width, peak group, and lock baseline options so that all peaks are found.
So for me the best solution would really be: Draw a line from 1.3 to 3.0 min and forget about all the shiny detection algorithms.
Any chance to do this?

Thanks in advance,
Jörg

[Csaba]

Hi,
In the detection tab of the integration view, you can set:
1 Sensitivity to 0.001 at 0 time (might give many peaks)
2 Peak group command to be active from 1.3 min to 3 min.
3 Integration inhibit on at 0 time.
4 Integration inhibit off at 1.3 min.
5 Integration inhibit on at 3 min.

Hope it helps.

[bunnahabhain]

Thanks Csaba but no, this does not do the job

Depending on the sensitivity settings I always have chromatograms that are integrated OK, but others that are not. Look at the attached examples to see what I mean.

Sensitivity: 200


Sensitivity: 220


If I go down with sensitivity (<= 100), no peak is detected for the first example chromatogram any more.

The only thing that would really work for me is to draw a line from data point at 1.3 in to the data point at 3.0 min and just take what is there (be it noise or noisy peak, never mind) and integrate it. My colleague on the GC says this is possible in Chemstation. I'm sure Chromeleon can do this, too, I just don't find out how.

Thanks again
joerg

[ACrawshaw]

Hi Jorg,

Have you tried setting the Sensitivity and Peak Slice settings graphically?

If you search for the following page "Modifying the Peak Recognition Algorithm" within the Chromeleon help, this may help.

The Sensitivity help page is also very useful to expain how both this criteria and Peak Slice work together.

Thanks

[bunnahabhain]

Hi Anthony

I tried setting these two parameters, but as I said before. The settings that work for one sample do not necessarily work for the next one. Therefore I'd like to skip all detection algorithms and just draw a line from 1.3 to 3.0 and treat everything above as "peak area". Isn't this possible?

Joerg

[ACrawshaw]

Hi Joerg,

If you mean Manual Integration then yes, this is completely possible. Just draw the baseline between the points you require. Obviously this will need to be done to all Chromatograms.

As you said you could get the integration events to integrate some of the Chromatograms correctly, I would still use these to reduce the number you need to manually manipulate.

Just one last thing to check. If you have a Minimum Area/Height/Width setting, are these either small enough or off completely to allow the software to dectect your peak of interest when you start adjusting the Peak Slice and Sensitivity settings? Just a thought...

Thanks

[bunnahabhain]

I found it, and I must say I was a little bit stupid.

My error was to use "Peak group start" and "end" with the "Auto parameter. Now I set it to fixed and it does exactly what I want. Thanks again Csaba for pushing me in the right direction.

Joerg