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Chemical/Petrochemical
GC Analysis of Total Reduced Sulfurs at ppbv Levels
Using an
Rxi™-l
ms Column and Sulfur Chemiluminescence Detection
by Silvia Martinez, In novations Chemist
• Reliable results for ppbv concentrations of highly active sulfur compounds.
Inert, low bleed column resolves all analytes.
• Column compatible with SCD and other sulfu r-specific detectors.
Through the Clean Air Act, the United States Environmental Prot ection Agency (US EPA) regulates and lim its the emission of toxic
air pollutants. The determinat ion of total redu ced sulfurs, as requ ired by CFR Title 40, requi res the use of methods and equipment
capable of providing full resolution as well as high sensitivity. Method s TO- IS, TO -I 6 and TO-I 6A describe GC proced ures that
apply to th e determination of redu ced sulfurs from stat iona ry sources, such as recovery furn aces, lime kilns, smelt dissolving tanks,
fuel gas combustion devices, tail gas contro l units, and others. Method TO - I6 specifies detectable conc entrations of ppbv levels for
dimethyl disulfide, dimethyl sulfide, hydrogen sulfid e, and me thyl merca pt an. Wh ile th ese meth ods do not specify th e ana lytical GC
column to use, they do state that the column must resolve the sulfur compoun ds.
Our new 100% dimethylpolysiloxane column, th e
Rxi' ">Ims column, provides th e ult ra-low bleed
required for low level detection and quant ification
of sulfur compounds. Its exceptional inertne ss
allows complete sepa ratio n of th ese very reactive
compoun ds, with excellent peak shape, at ppbv
levels. Wh en thi s colum n is coupled wit h a sulfur
chemiluminescence detector (SCD), th e analysis is
fast and simple.
For our examp le ana lysis, we collected a 20mL
sample of a gaseo us mixture of hydrogen sulfide,
carbo nyl sulfide, met hyl me rcaptan, ethyl mercap
tan, and dimeth yl sulfide in helium, using a
Sulfinertw-treated stainless steel sample loop. We
transferred the sample to a SilcoCa n" air moni
toring caniste r and press ur ized the can to 30psig
with d ry nitrogen. The
Sulfinertw
passivation
treatment on both the sample loop and canister
prevent ed adsorption losses of the highly active
sulfur compo unds. We intro duced a ImL aliquot
of the diluted gaseous mixture int o th e Rxi™-I ms
column via a second
Sulfinertv-treated
stainless
steel sample loop, using helium as a carr ier, and
analyzed the sample isotherma lly at 30°C.
Figure I shows the chromatography for the
red uced sulfu r compounds, demon strating full
resolution in less than S minutes. For collecting,
storing, and analyzing active sulfur compounds at
levels as low as single parts per billio n, the per
forma nces of
Sulfinertw
passivated containers and
transfer systems, and inert RxiTM_ Ims columns,
simply can't be equaled.
Rxi™-1ms Columns (fused silical
(Crossbond 100%dimethyl polysiloxane)
ID
df
Ipm)
temp.limits
length
cat
#
price
0.32mm 4.00 -60 to
330/350'C
30-Meter 13396
$460
2006.03
Figure 1 Total resolution of reduced sulfur compounds, in lessthan
5 minutes, using an Rxi™-l ms column .
1. hydrogensulfide
2. carbonylsulfide
3. methyl mercaptan
4. ethyl mercaptan
5. dimethyl sulfide
Iii" iii iii i i" " i' i I i i ' i' " ii i'
i '
i " ii' I ' i i " ii ' ' I
U
W
~
~
~
Time(min)
GC AR00861
Column:
Rxi™ -lms, 30m, 0.32mm 10,
4.00/lm
(cat.# 13396)
Sample:
hydrogensulfide, carbonyl sulfide, methyl mercaptan,ethyl mercaptan,
dimethylsulfide,100ppbveachin helium
Inj.:
1.mLsplitless, direct
Sample looptemp.: 30' C
Carrier gas:
helium, constant pressure
Linear velocity:
48cm/sec.
@
30'C
Oven temp.:
30'C
Del.:
sulfur chemiluminescence detector
Del.temp.:
800'C
Sample storage
&
transfer:
SilcoCan' air monitoringcanister withSiltek
O
treated1/4" valve(cat.# 24182-650); Sulfinert"
treatedgas sample loop, l ee(cat.# 22848); Sulfiner!" treatedgas sample loop, lOcc (custom
order)
for
more
info
SilcoCan™Canisters
Thebest alternative for ambient air monitoring
Recovery data for low ppb levels of active sulfur-containing compounds
show why
Silcocan"
canisters are the best choice for monitoring
TO-14,TO-IS, or reactive sulfur compounds. lit cat# S90llA
800-356-1688 °
www.restek.com• 20 •
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