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Jun 2001
Inlets
Agilent 6890 Gas Chromatograph Service Manual
Programmed Temperature Vaporization Inlet (PTV) 240
Solvent vent mode
Solvent vent mode
Stage 1: Sample and vent
In solvent vent mode, the sample is injected into a cold inlet. During sampling,
and for the duration of the venting, the solenoid valve is open. The solvent
vaporizes and is swept out the vent, while the sample deposits on the liner
walls or packing. If conditions are properly chosen and the sample is suitable,
analytes deposit in the inlet liner while the solvent evaporates and is swept
out. Large or multiple injections can be used to concentrate sample in the
inlet before transferring it to the column for analysis. Figure 240-4 shows the
inlet flow control with the septum head installed.
In the septumless head, the flows are the same as in the septum head except
the septum purge vent is bypassed directly to the carrier flow through the
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