Thermo Scientific FOCUS GC, Instruction Manual

Page: 103 / 356

Chapter 5
S/SL Injection Techniques Split/Splitless Injector (S/SL)
Instruction Manual 103
Splitless Injection Technique
Splitless injection is suitable for the analysis of compounds present in very low
concentrations.
The splitless technique allows the entire sample to enter the column without
splitting. This offers better sensitivity than the split technique.
With splitless injection, the split line is closed during the sample injection and
transfer to the column. Once the transfer is over, the split line opens to flush the
vaporization chamber of any remaining solvent vapors. Figure 5-6 shows the
split/spliless injector when used for splitless injection.
During splitless injection, when the split valves are closed, the flow of gas through
the injector is relatively low. It is equal to the column flow only a few mL/min.
The injector can accept and quantitatively transfer to the column sample volumes
of up to 5
μ
L (depending on the solvent type).
With injection volumes higher than 4-5
μ
L, the recovery of the sample injected is
generally improved by closing the septum purge together with the split valve
during the splitless period.
You can program this in the
INLET
menu when you select the
Splitless
mode.