Journal or ChromalograOh,eSc:ltlnce. Vor. 24. F6/)r",ary 1986
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8ASE NEUTRALS 200
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CF IO
16xlO- 10
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response to many hydrocarbon compounds. However, when
heteroatoms, such as 0,
Cl,
or P, arepresent in the sample com–
pounds, the FlO respons e is frequently significantly lower than
its response to hydrocarbons. In contrast, the CFID appears
10
yield more uniform response to all organic compounds
ir-
TI 0 - 1- 02
1 .. 10- 10
.'
\..
TID-%-H 2 , ...I .
16 .. 10-'
k
15
pg
e
IN ITR
OrOlUE
NES
tion provides very specific responses only to a ni tro-compound
(2,6-diniuotoluenej and a chlorinated compound (3,3 '-dichloro–
benzidene],
The lack of significant TID·j ·N, response
10nino–
benzene. bis(2-chloroethyl}ether, bis(2-chloro isopropyl}elher,
ora-bromcphenyt-pnenvl-erher
demonstrates that
the
TID-I·N,
response depends on how the electronegative funct icnallties are
bound up in the molecular structure of the sample compound.
When the detector gas environment of the TID·I source is
changed fromN, to
0 ..
the TID-I-O, mode provides enhanced.
relative responses to the chlorinated compounds and a diminished
relat ive response to the nitro-compound. The TlD-I·O, mode
continues to provide good discrimination
in
favor ofchlorinated
compounds with respect to hydrocarbons, while exhibitingsome
low level responses to phthalate compounds. TheTlD.2.H,/air
mode responds to all the N-compounds, with some small inter–
ferences fromchlorinated compounds . The FTID· I mode uses
a TID-I source and provides responses [0 all the nitrogen and
halogen compounds in [he sample. The FTIO-2 mode uses a
TID-2 source which produces responses to the halogenatedcom.
pounds but suppressed responses to nitrogen compounds in
comparison
10
FTIO-l . This set ofsix chromatograms provides
a good illustration of how the detector response can
be
varied
through simple changes in the composition of the detector gas
environment.
Figure g'shows chromatograms ofa samplemixtureconsisting
of 75 ng each of 2-chlorophenol, 2-nitrophenol. phenol, 2,4-di–
methlyphencl, and 2,4 dichJorophenol; 2IS ng each of 2,4,6-tri–
chlorophenol. and 2.4-dinitrophenol; and 375 ng each of
4–
cblcro-e-crescr,
4.6-dinitro-o-cresol. pentachlorophenol. and
4-nitrophenol. The CFIDprovides a relativelyunifonn response
of 0.004 coul/ge for aUthese compounds . (Note; The flame
tip orifice for these CFIO data was 0.062 in. instead of 0.031
in., which is nonnally used. The smaller orifice usually provides
improved sensitivities of approximately 0.01 coul/gC.)
The CFIO data providea good illustration ofa principal dlf–
terence in the responses of a CFID vs. a convent ional FID.
It
iswell known that conventional FIDs provide relat ivelyuniform
1 X
10- 12
2,"
N
3 . 2 '"
2,"
FTI O- 2
FlQure6
Cnrcmatoqrams
etlmparingthe responses
01
the
TID·
I-N2mode and
tne
T1D·2·H
2/
alr (NP)mode totraces
0'
dlMrotoluenes.Column:SP·2100. 160°
to 2OO"Cat 10o/mill.
Figure
7.
Chromatograms shOW1ng
six
diHerent modes
01
uetectcr response
toasampleo!
base
neutral compounds, !nincreaSIng order
01
retention
lime.
thecomponents
01
thesample are bls(2·chlofoethy!)etner: bls(2-chlorClSOpro–
py!\etller:
mtrotereene:
acenaphlhylene: dimetnyrpl'ill'lalate:2.6-tlinitrotl)/uene:
4-bromophenyl·phenyl ether: dl·ll·butylphthalate: blS/2-etllyll'lexyllpl'ilhalate:
3.
3··dlc/lorobenzu:lIne: and benlO(bl"lIOranthent Column: SP-2250; l00"C. held
lor 4min. then 10 " to 270"C
at
16°/mln.
46
