DETector Engineering
&
Technology, inc.
486N.Wiget Lane,Walnut Creek,CA 94598USA
telephone: (925) 937-4203
fax: (925) 937-7581
DEI
e-mail:
innovations in chemical detection
Reactor Thermionic Ionization Analysis (RTIA)
selective TID/NPD transducer screening ofvapors evolved from
THERMAL DESORPTION/OXIDATION
of
,~onvo
latile
liquid residues or solid sample constituents
Background:
Thermal desorption continues to be an
HEATING
increasinglypopularmeansof preparing realworldsamples
CURRENT
for subsequent analysis by gas chromatography. Among
the many different types of GC detectors, TID and NPO
detectors have the distinctive characteristic that they can
provide chemical species selectivity using Air as the
primary detector gas. Consequently, these detectors are
well suited to non-GC chemical screening applications
where the gas environment is simply ambient Air drawn
through aTIO/NPO transducer by a sampling pump. In an
RTIA configuration, such a transducer is preceded by a
heated reactor chamber into which are inserted solid
samples packed intoaglass tube or liquidsample residues
on a ceramic rod. The TID or NPO transducer provides
selective responses to vapors evolved from thermal
desorption and/or.oxidation of the samples. At low reactor
temperatures, thermal desorptionusuallyaccounts formost
detected signals, while at high tempera tures oxidative
sampledecompositionproducts often provide large signals.
Good examples of the oxidative detection processes are
large T10-1 signals from oxidation of sugars and proteins.
For T10-1 and T10-3 thermionic detection, only Air is
AIR
required as theoperating gas,while for NPOasmall flow of
Hydrogen has to also be introduced into the incoming Air.
THERMIONIC
SOURCE
HEATED
REACTOR
GLASSWOOL
ORFRIT
GLASS TUBE
._ HYDROGEN (NPD)
OR CAPPED (TID-1)
i-Propanol Wipe Transfer of Surface Residue to 1/16 in.
Ceramic Rod - Rod inserted into 140 deg C Reactor
TID-1-Air
80
pA f.s.
Air-GOOmUmin
Wipe of Clean
Table Top
I
Wipe of
/ TNT residue
on Table Top
rod taken
out of
reactor
I
2nd Wipe of
/ Residual TNT
on Table Top
rod out of
reactor
I
Malathion Residue on Quartz Rod
NPD, 160 pA f.s., Hydr.=4.3, Air=200
Malathion
in Methanol
rod dipped into sample Methanol evaporated rod residue inserted into
140deg C reactor
- 0.1
mg/mL
dried
TNT
residue on a table top wiped with an small quartz rod dipped into a
O.1mg/mL
solution
iso-propanol pad and transferred to ceramic rod. of Malathion in Methanol.
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E-mail :
TelNo : 03 9762 29034 . . . inAUSTRALIA
