Constant column + makeup flow

Question

Hi,

I am using a 6890 GC in split mode with an isothermal temperature and no flow ramp and operating in constant pressure mode.

Please can you advise how using the setting constant makeup flow for the FID detector is different to constant column and makeup? Under the method conditions stated will the flows be the same if either setting is used?

Thanks

james_jenkins · Accepted Answer

Hi camelia,

If you are running an oven temperature profile rather than isothermal, constant column and makeup will adjust the make up gas to compensate for flow changes as the column flow decreases. This helps keep the detector output (baseline) relatively constant. Using isothermal in your case , either setting will essentially perform the same.

Regards

James