Chromatography Forum

Hey all,

I am a quite new user of a GC Aligent 7820, measuring SCFAs, extracted from faecal samples, and I would like to ask you how could I update the window of each peak from the external standards? They are very broad and they overlap each other. Furthermore, working on the samples, in some specific retention times two peaks are detected instead of one, just because the windows are so broad.....

Hope to explain quite well and somebody can reply me.
Thank you very much.
KonstantinaZaf

Hello

To answer your question...As I understand you want Chemstation to recognize (identify) standard peak on different calibration levels (based on retention time). See instruction below:
1.Go to Data Analysis mode
2.Go to Calibration line
3.Go to Calibration setting
4.You have "Reference Peak" and "Other Peak" line. Change default percent value (5%) to higher/lower (for example 1% or 10%)
You should now have broader/narrower blue region where your peak is identify.

Please note: if you have 2 peaks coueluting in region where your standard is you can identify wrong compounds. But it is completly different story.

Regards

Tomasz Kubowicz

Welcome to the forum.

If you can improve the chromatography to give sharper, separated peaks you will solve this problem as well as generating results that are much more accurate.

Peter