Chromatography Forum

used nitrogen instead of helium. Could it cause any problem? just run like twenty minutes.

It depends. If the mass spec was off - not a problem.

If the mass spec was on - maybe. If you were acquiring m/z 28, you may have beat up your detector a bit. With the instrument switched over to He and the lines carefully purged, tune the instrument and see how it does. If you get a good tune with about the same signal intensity at the about the same detector voltage - no harm done.

Normally, the software will prompt an error message because you have to define the carrier gas as He when editing the method.

Ths sounds like putting a nitrogen bottle on the regulator where it should have been a helium bottle - and they can be switched this way. The software has no idea what is actually coming through the plumbing.

Agilent is now selling a device for the 7890 GCs to switch your carrier gas to nitrogen while at idle. For those of us with instruments that are frequently parked it could save quite a bit of helium. Of course those instruments don't get replaced very often so maybe by the time I retire...

Ths sounds like putting a nitrogen bottle on the regulator where it should have been a helium bottle - and they can be switched this way. The software has no idea what is actually coming through the plumbing.

The software does not know what gas it is, but the gas viscosity is different so it fails to maintain the right flowrate.

Thanks god. I did not acquire 28, nitrogen gas. so that is fine.

It depends. If the mass spec was off - not a problem.

If the mass spec was on - maybe. If you were acquiring m/z 28, you may have beat up your detector a bit. With the instrument switched over to He and the lines carefully purged, tune the instrument and see how it does. If you get a good tune with about the same signal intensity at the about the same detector voltage - no harm done.

Other than possibly some wear on the filament it shouldn't be an issue.

Agilent is now selling a device for the 7890 GCs to switch your carrier gas to nitrogen while at idle.

A valve? really that's all it would take, and just set the gas to nitrogen in yoru standby method, helium in your analysis method. Chemstation would probably flip out at this point and report some mismatch, but Openlab doesn't, it just gets on with it (see, there are some advatages!). I guess there will always be people who can't turn a valve though, and Agilent have answer for them!

Agilent is now selling a device for the 7890 GCs to switch your carrier gas to nitrogen while at idle.

A valve? really that's all it would take, and just set the gas to nitrogen in yoru standby method, helium in your analysis method. Chemstation would probably flip out at this point and report some mismatch, but Openlab doesn't, it just gets on with it (see, there are some advatages!). I guess there will always be people who can't turn a valve though, and Agilent have answer for them!

The trouble is that the accreditation cops would require the valve to be certified, there would have to be an SOP for when and how to turn the valve, and everyone would have to have training in valve turning, suitably documented in their training files. Then each time the valve was turned it would have to be documented and signed off. So it's actually much easier to include it in the instrument setup and let the software do the paperwork. Sad really.

Peter

Agilent is now selling a device for the 7890 GCs to switch your carrier gas to nitrogen while at idle.

A valve? really that's all it would take, and just set the gas to nitrogen in yoru standby method, helium in your analysis method. Chemstation would probably flip out at this point and report some mismatch, but Openlab doesn't, it just gets on with it (see, there are some advatages!). I guess there will always be people who can't turn a valve though, and Agilent have answer for them!

The trouble is that the accreditation cops would require the valve to be certified, there would have to be an SOP for when and how to turn the valve, and everyone would have to have training in valve turning, suitably documented in their training files. Then each time the valve was turned it would have to be documented and signed off. So it's actually much easier to include it in the instrument setup and let the software do the paperwork. Sad really.

Peter

Yup, takes more lawyers than scientist to run a sample these days.