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GCDetectors
TID - Thermionic IonizationDetector
• HighlySelective toNitroFunctional Groups
• Also responds tochlorinatedphenols
• Detectsdown to 1ppb
• Convenient beaddesign
• Canbe runGasless in thefield!
Thischromatogramshows
the separationof a10ppm
explosives sample.
TIDbead
The TID is similar in design to the FID and NPD. The electrically
heated thermionic bead (TID bead) is positioned so that the column
efluent contacts the hot bead surface. Analytemolecules 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, ampliied, andoutput to thedata system.
TIDbead
TheThermionic IonizationDetector isextremely selective, having littleor no response tomost aromaticand
aliphatic hydrocarbons. The TID also responds to chlorinatedphenols such as pentachlorophenol (PCP) at
slightly less sensitivity.
Forbest sensitivity, theTID requiresair for operation. If air isusedas thecarrier gas, nootherdetector gases
are required.Anairmakeupgas isprovidedso that nitrogenor another gascanbeusedasacarrier. TheTID
can alsobe operated in a nitrogenonly environment with similar but not identical response characteristics.
(ETV) program formeasuringexplosives in soil!
Testedby theEPA’sEnvironmental TechnologiesVerification
Download theETV report and veriication statement at
Also, download “On-SiteCharacterizationof ExplosiveResidues inSoils andonRangeScrapUsingGC-TIDAnalysis”
byAlanHewitt of theUSArmyCorps of Engineers at
8690-0017
TIDdetector
