ISQ User Guide - Write Frame of Mind

4 Creating a Method
c. Click the Carrier tab, which is used to set the carrier gas flows. The gas flow and the
oven temperature work together to determine how well the analytes are separated and
how long the analysis will take. You can select either constant pressure or constant
flow. If you use constant pressure, as the column is heated in the oven, the flow rate
will fall because a hotter column is more resistant to carrier gas flow. If you use
constant flow, the carrier gas pressure will increase as the column temperature
increases to keep the flow constant. Constant flow is more common. Typical flow
rates are 1-3 mL/min. The pressure depends on the column length and internal
dimensions, so there is not a typical value. Because the outlet of the column is in the
ISQ, which is under vacuum, the vacuum compensation should be on.
In an effort to reduce the amount of carrier gas used, you can activate the Gas Saver
mode. When used, the split flow will be reduced to the gas saver flow after the gas
saver time. It is not recommended to use a flow of less than 20 mL/min because
contaminants can build up in the injector, column, and ISQ, which can affect system
performance.
Thermo Scientific ISQ User Guide 47