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Help meee
Posted: Fri Aug 11, 2017 2:27 pm
by Aalia
Anybody who are using gas chromatography 7890A help me. I am using GC7890A with cp-wax 58 ffap 25m length 0.53mm diameter column. But it is not working tried so many times stilll flame out. Once light out and inject one or two sample then flame out. What i do help mee plzzzÂ
Re: Help meee
Posted: Fri Aug 11, 2017 3:10 pm
by Consumer Products Guy
Don't double post !
Re: Help meee
Posted: Fri Aug 11, 2017 3:56 pm
by AaronAIT
Are you injecting water as your solvent? If so, try reducing the injection volume as a first port of call.
Re: Help meee
Posted: Fri Aug 11, 2017 7:05 pm
by James_Ball
Need to know injection solvent, column flow rates, gas flow rates in FID and any other information we can get to help.
Re: Help meee
Posted: Sat Aug 12, 2017 2:51 am
by Aalia
Sorry for double posting. I really need help
Injection volume 0.1ul, pressure 0.8 psi, total flow-183 Ml/min, septum purge flow-1ml/min, split ratio 150:1, air-200 ml/min, h2-20ml/min, he- 15ml/min.
Washing solvent-ethanol .
Injection solvent- benzene and isooctane standard
Re: Help meee
Posted: Sat Aug 12, 2017 3:44 pm
by HPLC chemist
You didn't include the Hydrogen flow going to the FID? It will need this as well as Air/Oxygen to ignite the flame.
Re: Help meee
Posted: Sat Aug 12, 2017 4:42 pm
by dblux_
What value of "Lit off" have you set ?
Re: Help meee
Posted: Mon Aug 14, 2017 8:09 am
by Peter Apps
Your carrier gas flows and pressures are really strange; you only have about 1.2 ml/min going down the column, which is much too little for a 530 um diameter column. It would be about right for a 250 um column. Where did the method come from ? Have you used it before ?
Depending what you are injecting (and 0.1 ul sample with a 150:1 split suggests it is something strange) the very low inlet pressure and carrier flow mean that the pressure pulse as the sample flash vaporizes will cause a flow pulse down the column, which might blow out the flame.
Peter