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TID - SRI Instruments
TID - Thermionic Ionization Detector
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selective to nitro functional groups
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Also responds to chlorinated phenols
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Detects down to 1 ppb
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Convenient bead design
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Can be operated gasless
The Thermionic Ionization Detector is similar in design to the
and
. The electrically heated thermionic bead
(TID bead) is positioned so that the column effluent contacts the hot bead surface. Analyte molecules containing NO
2
(nitro) functional groups such as TNT (trinitrotoluene) undergo a catalytic surface chemistry reaction. The resulting ions
are attracted to a collector electrode, amplified, then output to the data system.
The TID is extremely selective, having little or no response to most aromatic and aliphatic hydrocarbons. This detector
also responds to chlorinated phenols, such as pentachlorophenol (PCP), at slightly less sensitivity.
For optimum sensitivity, the TID requires air for operation. If air is used as the carrier gas, no other detector gases
are required. An air makeup gas is provided so that nitrogen or another gas can be used as a carrier. The TID can also
be operated in a nitrogen only environment with similar but not identical response characteristics.
This chromatogram shows the
separation of a 10ppm explosives
sample.