Chromatography Forum

Hello everyone,

First, do we have to turn off GC everyday before we leave the lab? Do we just create a "sleeping" method with low gas flow rate and temperature when we are not using it? Is it safe to leave gases like hydrogen or oxygen flowing over-night without monitoring?

If we do want to turn off the GC, what steps should I follow?

Thanks,
Nina

GCs can safely be left overnight at whatever settings they are on during the day - thousands of them all over the world run automatically overnight. If you do want to put one to sleep overnight just reduce the oven temperature to a bit above room temp, leave the detectors and injectors at working temp, shut off the detector gasses (for ECD leave the make-up on), and use the gas saver feature to set a lower (20 - 30 ml/min) flow through the inlet.

Peter

First, do we have to turn off GC everyday before we leave the lab?Is it safe to leave gases like hydrogen or oxygen flowing over-night without monitoring?
1st - definitely nope.
As for hydrogen. Read the manual. If it warnes not to leave FID unatended then you shouldn't - there will be no excuse in the worst case, you should be aware of every precautions from manual. But finally the decision is yours. You have to consider if it would be possible that hydrogen concentration might reach LEL in case of leak taking into account cubature of the room, ventillation etc.

If we do want to turn off the GC, what steps should I follow?
Cool down heating zones.

GCs can safely be left overnight at whatever settings they are on during the day - thousands of them all over the world run automatically overnight. If you do want to put one to sleep overnight just reduce the oven temperature to a bit above room temp, leave the detectors and injectors at working temp, shut off the detector gasses (for ECD leave the make-up on), and use the gas saver feature to set a lower (20 - 30 ml/min) flow through the inlet.

Peter

Thanks, your answer helps a lot.
Nina