Thermo Scientific FOCUS GC Instruction Manual page 95

S/SL Overview
For both split and splitless applications, the sample is injected through a septum
into a glass liner in the vaporization chamber.
The technique used, either split or splitless, determines the choice of the glass
liner and the length of the syringe needle. You can control the injector
temperature from ambient to 375 °C, although the actual injector temperature you
use depends on the solvent choice and thermal stability of the samples.
The Digital Pressure Flow Control (DPFC) controls the split flow, while the
septum purge flow is kept constant by a calibrated flow regulator.
The S/SL injector is also equipped with electronically actuated On/Off valves for
split and septum purge lines.
Volatile components given off by the hot septum can produce ghost peaks in a
chromatogram. The septum purge system can continually purge the septum with a
flow of gas. This prevents the volatile components given off by the septum from
entering the column. Figure 5-2 shows the septum purge system.
Figure 5-3 shows the S/SL injector components.
Instruction Manual
1. Spring
2. Septum
3. Septum Holder
4. Septum Support
5. Liner Cap
6. Graphite Liner Seal
7. Glass Liner
A. Carrier Gas Inlet
B. Septum Purge Line
C. Split Line
Figure 5-2. Septum Purge System
Chapter 5
Split/Splitless Injector (S/SL)
95