ISQ User Guide - Write Frame of Mind

4 Creating a Method
b. If you have a split / splitless inlet (SSL) injector, click the SSL tab to configure the
injector port settings.
The inlet should be turned on and set to a temperature that is at least 10 °C
higher than the boiling point of your least volatile analyte. The material injected
into the port will vaporize and move into the GC column quickly. Higher
temperatures can lead to thermal decomposition of some analytes, so you will
have to optimize the injector temperature for your analysis. Set the SSL
temperature between 50 and 375 °C (a typical value would be 225 °C).
Useful for diluting high concentrations of sample, the split flow is the amount of
gas that is swept through the injector to the exhaust port. Higher values will give
more dilution. The split flow will also reduce the amount of contamination that
builds up in your system. The split flow ratio is the ratio of the split flow to the
carrier gas flow. It is effectively the dilution ratio of the sample. This is typically
turned on and set to a flow of 50 mL/min. However, this increases the carrier gas
usage, so for your analysis, lower split flows may be more acceptable.
We recommend turning on the septum purge, which means an additional 5
mL/min of carrier gas will go through the injector. This reduces the buildup of
contaminants in the injector, on the column, and in the ISQ. If you perform a
splitless injection, even if the split flow is set, the split flow will be turned off for
the splitless time. The septum purge will be turned off for the stop purge time.
After these times, the split flow and septum purge will be reactivated.
Finally, if your analysis requires a higher flow to quickly sweep the analytes into
the column, which may be needed with high temperature injectors and thermally
labile compounds, you can use the surge pressure to increase the column flow for
the surge duration time.
46 ISQ User Guide Thermo Scientific