INFICON HAPSITE Smart Plus Chemical Identification System - Manual (Page 34)

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HAPSITE Smart Plus Operating Manual
Figure 1-2 Total Ion Chromatogram
The performance of the column is affected by temperature, therefore, the column
is housed in a temperature controlled oven.
The gas chromatograph performs many operational functions, including injecting
the sample, analyzing the sample, flushing the system, and tuning the system.
GC/MS measurement begins with the Sample Pump drawing the gas to be
analyzed into the Sample Loop. It then uses the pressure of the Carrier Gas to flush
the sample from the Sample Loop on to the pre-column and the analytical column.
This step is termed injection.
When the analytes have passed through the pre-column, the Carrier Gas is
directed to the junction of the two columns where the Carrier Gas continues to
transport the analytes through the analytical column while back-flushing the
pre-column to prepare the pre-column for the next analysis sequence. This
back-flush continues throughout the next filling of the Sample Loop.
1.6.1.1 Membrane Isolation Valve
Gas exiting the analytical column crosses the face of a membrane mounted in the
membrane isolation valve. This membrane has the special characteristic of
transmitting the flow of organic compounds to the Mass Spectrometer, while
effectively blocking the flow of inorganic gases (such as the Nitrogen Carrier Gas).
When the membrane isolation valve is opened, the appropriate gases are
permitted to enter the Mass Spectrometer for analysis while the Mass
Spectrometer remains under vacuum. The membrane’s performance is affected by
temperature fluctuations and requires housing in a temperature-controlled zone.