Inlet Systems

Split/splitless capillary inlet

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.

Figure 6-13

Solvent

Sample

Plunger

Air

Properly Filled Syringe for Split or Splitless Sampling

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.

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