INFICON HAPSITE Smart Plus Chemical Identification System - Manual (Page 31)

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HAPSITE Smart Plus Operating Manual
Internal Standards Gas Use-Rate . . . . . . . 1 canister per 24 hours of operation
(This depends on the details of the
method being used.)
Battery Life . . . . . . . . . . . . . . . . . . . . . . . . Approximately 2 to 3 hours.
1.3 Serial Number Location
The serial number of the HAPSITE is located on the inside of the front panel and
on the touchscreen. Touch the HAPSITE icon, followed by the HAPSITE System
icon, and then touch HAPS to locate it.
1.4 Theory of Operation
The HAPSITE combines two analytical techniques, Gas Chromatography and
Mass Spectrometry, to separate, identify, and measure the organic components in
a gas phase sample. Using a flow of inert Nitrogen Carrier Gas, the Gas
Chromatograph (GC) performs a time separation (Retention Time) of the sample
compounds. The separation order is primarily based on increasing compound
boiling point. The Mass Spectrometer (MS) detects and identifies the eluting
compounds by breaking the molecules apart and detecting the fragments. The
resulting mass spectrum is compared to a library of mass spectra to identify the
compound.
The Gas Chromatography technique cannot always separate compound mixtures
into individually eluting compounds. Some of the eluting responses or peaks may
contain two, three, or more compounds which have taken the same time to
progress (elute) through the Gas Chromatograph. GC identification of compounds
is limited to matching the retention time of the unknown compound to that of a
known standard. See
section 1.6.1, Gas Chromatograph, on page 1-5 for more
information on how the GC works. In order to further identify and measure the
individual components of such mixtures, the gas stream is directed into the Mass
Spectrometer.
In the Mass Spectrometer, the gas stream of eluting compounds is bombarded with
electrons. The electrons fracture the molecules into a characteristic combination of
smaller molecules or mass fragments. The Mass Spectrometer (MS) measures
and plots the response of these mass fragments to display a mass spectrum. See
section 1.6.2, Mass Spectrometer, on page 1-7 for more information on how the
MS works.
The introduction of a mixture of many compounds directly to the MS would produce
a very complex and uncharacteristic mass spectrum. However, because the GC
has largely separated the gases, the MS can usually differentiate between the few
co-eluting compounds. This differentiation provides very precise identification and
measurement of the quantity of each compound. Qualitative identification can be
made by comparing the unknown compound spectrum to the NIST mass spectral