Standby GC-ECD / MS

[Laura._]

Hello,
I use Agilent GC ECD/MS and I want to put my GC into "standby/sleep" mode during night... I thing that ex-collegue put oven off, inlet off and also front detector (ECD) off, but make-up si on - manually with keyboard. I think that make up gas is on and also pressure on column. What is the best way to achieve "save gases-sleep mode" without GC damage?
I think that when GC-MSD is used, Aux is always on, oven, inlet - off.
Should column have always set flow through column? What kind of flow settings would you recommend me to use to save as much gas as possible?
How long then stabilization lasts?
Thank you

[James_Ball]

Always best to keep some flow through the column. For a narrow bore 0.25mm column I use 0.2-0.3ml/min and oven at 35c-50c. This will leave a low head pressure so if you want less flow you may need to raise oven temperature to have enough inlet head pressure to support the flow.

If you will run it every day but shutdown at night leave temperatures on, it probably takes less electricity to maintain a high temperature than to bring it back up to temperature after it has cooled down.

We normally leave oven temp at 150c and column flow at 0.3ml/min and split ratio at 5:1 for a standby, this keeps thing cleaner than letting it sit at low temperatures for a long time. You can also plumb in valves to switch to hydrogen or nitrogen carrier to conserve helium if that is what you are worried about.