The PTV Injection Procedures

The splitless injection for the injection of a maximum sample equivalent on to the column is the standard requirement for residue analysis. The sample is taken up in a suitable solvent and injected at a low temperature. The split valve is closed. The PTV temperature at injection should correspond to the boiling point of the solvent at ambient pressure. During the injection phase, the oven temperature is kept below the PTV temperature. It must be below the boiling point of the 

At the same time, this front migrates and evaporates in the carrier gas flow, (b) The 

Filling the insert with silanized glass wool has proved effective for the absorption of the sample hquid and for rapid heat exchange. However, the glass wool clearly contributes to enlarging the active surface area of the injector and should therefore be used only in the analysis of noncritical compounds (alkanes, chlorinated hydrocarbons, etc.). For the injection of polar or basic components special care is required keeping the glass wool deactivated by frequent replacements, an empty deactivated insert is recommended. 

All other PTV adjustments of time and temperature are completely unchanged compared with total sample transfer Of particular importance for the split injection using the PTV cold injection system is the fact that the sample is injected into the cold injector (see also Section 2.2.7.5). The choice of start temperature of the G C oven is now no longer coupled to the boiling point of the solvent because of the solvent effect and is chosen according to the retention conditions (Tipler and Johnson, 1989). 

To inject larger sample volumes (from about 2pL to well over 100 pL), it is advantageous for the insert to be filled at least with silanized glass wool or packing of Tenax, Chromosorb, Supelcoport or another inert carrier material about 0.5-1cm wide. The split valve is open during the injection phase. The PTV is kept at a temperature that corresponds to the boiling point of 

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