- Hewlett-Packard Reference Manual

Inlet Systems
Split/splitless capillary inlet
122
2. Wipe excess solvent from the syringe needle.
3. Without introducing air, draw in excess sample.
4. Position the syringe plunger for the required injection volume. Wipe
excess sample from the needle.
5. Draw in air until the sample/solvent is entirely within the syringe
barrel. The sample is ready for injection.
This method results in the syringe filled as shown in Figure 6•13.
Air
Sample
Solvent
Plunger
Properly Filled Syringe for Split or Splitless Sampling
Figure 6-13
Solvent following the sample (about 0.7 l) helps to wash sample
components from the syringe and needle bore.
For split sampling, with high gas velocity through the inlet, injection
must be made in a continuous, rapid manner. Any lack of smooth motion
may cause multiple injections.
For splitless sampling, with low gas velocity through the inlet, injection
may be at a slower pace, but must also be done smoothly. Also, note that
retention times depend upon amount injected, so total sample volume
injected should be kept constant.
Note: In analyzing samples containing heavy components (e.g., C
with
a boiling point of 391
C), it may be necessary to leave the needle in the
inlet for up to 10 seconds after injection. This reduces needle
fractionation occurring with such components.