Split ratio

In Agilent 7697A Model Head Space GC,

we face following problems;
1.Split ratio for method mentioned as 1:2, can we keep it 0.5:1,
2. split ratio is very low the flow rate is not stable. during the heating process it is leading to alarm.
Any Analytical experts request to give solution.

  • What is the inlet total flow?  It should be at least 20 for accurate flow control.  Also, if you have a 7890 or 8890, were the inlet PID constants changed to reflect that the 7697 is in-line?  That way the GC knows the extra tubing is there.  For 7890 you need to connect to the GC using the firmware update tool.  On 8890 it can be done from the touchscreen through Service Mode.

  • Dear Vinod,

    The split ratio is too low for the split valve. You have two options. First is use a higher split ratio, it will generate higher flow in the inlet and there will be no problem during the heating process. Second option is use splitless injection.

Was this helpful?