Chromatography Forum

Hi,

I have a little side project where I want to create a stand-by method for all our GC's: low flow, splitless, etc.

But i don't have hands-on experience with GC-FID. We have a couple of those machines running. What would the recommended settings of this detector be to conserve some gas/energy while still able to start a method the next morning without much problems? Turn off the flame? I've searched the net but can't really find this info.

Turn off the flame, fuel gasses (air and hydrogen) and eventual makeup gas (usually nitrogen).

Where do you get your gases from?

Usually, there's no reason for turning off the FID ever (in my limited experience), if you don't actually need to conserve gases.
The longer it stays lit the more stable it will be.

In our lab we use dry air from an external compressor, hydrogen from a generator and nitrogen is cheap and plentiful so who cares and we keep it on and hot for as long as possible.

markf wrote:
Where do you get your gases from?

Usually, there's no reason for turning off the FID ever (in my limited experience), if you don't actually need to conserve gases.
The longer it stays lit the more stable it will be.

In our lab we use dry air from an external compressor, hydrogen from a generator and nitrogen is cheap and plentiful so who cares and we keep it on and hot for as long as possible.

We get our gases from the same sources as you do.

I haven't made a calculation on the savings of energy/gases. My starting point was that every little bit helps, if it doesn't impact the analysis the next day.

I generally turn them off if they're not being used to collect data. I've operated this way for 25 years without problems. When I light the detector in the morning, I run the temperature of the oven up to boil off any contaminants (bleeding septa, etc.) that collected while the detector was off and when I cool it, I'm ready to go.

For my instruments that have electronic pressure control, I generally reduced the inlet pressure (and thus, the flow through the column) to conserve helium. You need to keep some flow through the column when it's installed.

Good luck!

We set all of our GCs to standby, turning off the Hydrogen and Air, when not in use.

It saves on gas, but I would also like to know if there is any consensus on whether there are any deleterious effects from keeping the flame off as much as possible. Could material build up on the jet without a flame to pyrolize them?