Hot Needle Thermo Spray Injection Technique

The hot needle injection can be used with hot SSL injectors both in spht and splitless modes, using an empty inlet liner. Common to the hot needle techniques is that the sample plug is pulled up into the barrel of the syringe. A short delay of 3-5 s is used after the syringe needle entered the injector for heating up the 

Understanding the relationships between inlet liner geometry, carrier gas flow, injection volume and solvent vapour volume is essential for optimizing splitless injections. Especially the expansion volume of the solvent used must be taken into account. The maximum liquid injection volume needs to be adjusted in the hot 

Injection volume ( iL) H OliiL) CSj (lit) CHjClj (lit) Hexane ( iL) Iso-Octane ( iL) 

The expansion volumes given here refer to an injection temperature of 250 °C and a column pressure of 0.7 bar (10 psi). The values for other temperatures and pressures can be calculated according to = lIP-tfR T, 

To determine the time required to flush the contents of the injector completely on to the column at least twice the insert volume is applied, corresponding to a yield of 90 - 95 %. During transfer of the sample and solvent vapor cloud into the column the re-condensation on the column head exploiting the solvent effect is required. The minimum isothermal time of the oven temperature to stay below the effective solvent boiling is calculated from twice the inlet liner volume by the set carrier gas flow rate, see also Table 2.22. 

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Figure 2S7 Hot needle thermo spray injection technique (in splitless mode).

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