Agilent Technologies 6890 Series Service Manual page 110

240 Programmed Temperature
Vaporization Inlet (PTV)
Theory of operation
The Programmed Temperature Vaporization (PTV) Inlet collects each portion
of an injected sample inside a 120 microliter liner until the entire quantity of
sample is obtained. During the hold, the sample is held at a programmable
temperature as low as –60°C using CO
liquid nitrogen. When the complete sample is collected, the PTV heats and
delivers the sample onto the column.
The PTV can be used with either a septum or septumless head, operating in
either split, splitless, or solvent vent modes.
In the solvent vent mode, analytes are thermally trapped in the liner while
the solvent is removed. With the solvent gone, the liner volume can be used
for another injection. Injection can be repeated several times to concentrate
the analytes from a large sample volume. After injection and solvent removal,
the analytes are transferred to the column. This can replace the need for
offline reconcentrating and minimize loss of sample.
Operating modes
The Agilent Programmed Temperature Vaporization (PTV) Inlet System has
five operating modes:
• The split mode is generally used for major component analyses.
• The pulsed split mode is like the split mode, but applies a pressure pulse
to the inlet during sample introduction to speed the transfer of material
onto the column.
• The splitless mode is used for trace analyses.
• The pulsed splitless mode provides a pressure pulse during sample
introduction.
• The solvent vent mode collects analyte in the liner while venting solvent,
and is used for large volume injection. Either single or multiple injections
can be made for each run.
Jun 2001
Inlets
Agilent 6890 Gas Chromatograph Service Manual
cooling, or as low as –160°C using
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