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Agilent 7890B GC Species Detection Limit

http://www.chromforum.org/viewtopic.php?t=52494

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Agilent 7890B GC Species Detection Limit

Posted: Tue Nov 28, 2017 2:30 am
by temaire
I have an Agilent 7890B GC with model #: G3440B. It has a FID and two TCDs. I'm wondering how I can find out what the detection limits are for the gas species that I can measure. For example, I'm pretty sure the detection limit for hydrocarbons using the FID is 5 ppm. However, I'm not sure what the detection limits are for oxygen, nitrogen, carbon dioxide, carbon monoxide, helium, etc., are using the TCDs. Any help would be appreciated.

Re: Agilent 7890B GC Species Detection Limit

Posted: Tue Nov 28, 2017 6:46 am
by Peter Apps
You run a series of standards of known concentration, the detection limit is somewhere between the concentration for the smallest peak you can see, and the next one down. More formally you need to find what concentration gives a signal: baseline noise ratio of 3:1.

Peter
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