Sulfurs inSilcoCan
™
Canisters
Long-TermStabilityofVeryLow-Level
(1-20ppbv)ReactiveSulfurs
APPLICATIONS
NOTE
Introduction
Collection andmeasurement of sulfur-containing volatile organic compounds (VOCs), such as hydro-
gen sulfide,methylmercaptan, ethylmercaptan, anddimethyl disulfide in the atmosphere is verydiffi-
cult because of their low concentrations andhigh reactivity. SulfurVOCs can react not onlywith each
other, but alsowith the vessels inwhich they are collected.This causes low recoveries. InTedlar
®
bags,
the stabilityof low-level (100ppbv) sulfurVOCs is poor, evenwithin24hours of sampling.
1
Sulfur
compounds reactwith themetal surface in electropolished canisters, so these canisters areunsuitable
for collecting and storing low-level sulfurVOCs.
2
When youneed toperform sensitive airmonitoring analyses, use SilcoCan
™
canisters to collect and
store samples. SilcoCan
™
canisters,which feature a Siltek
®
-treated surface, offer superior storage stability.
We evaluated the stabilityof sulfurVOCs inSilcoCan
™
canisters at very low levels (1–20ppbv) for six
days, under dryor humid conditions, todemonstrate the excellent abilityof SilcoCan
™
canisters to store
low-level sulfurVOCs (Figure 1).Hydrogen sulfide,methylmercaptan, and ethylmercaptan rapidly
degraded in electropolished canisters.
AnalyticalSystem
High resolution capillary gas chromatography (GC) in conjunctionwith sensitive, selective detectors
such as sulfur chemiluminescence detectors (SCD) or flame photometric detectors (FPD) offersmany
advantages for trace analysis of sulfurVOCs. For this study,weused anRtx
®
-1 capillary column, a
Siltek
®
treated six-portValco
®
valve, and a Siltek
®
treated1mL sample loop and
1
/
16
" sample pathway.A
representative chromatogram for the sulfur compounds is shown inFigure 2.
Figure1
Stabilitydatademonstrateabilityof SilcoCan™ canisters to store low-level
organic sulfur compounds in real-world conditions.
Rtx
®
-1, 60m, 0.53mm ID, 7.0µm (cat.# 10193)
GC:
Agilent 5890GC
Det.:
SieversModel 355 SCD
Oven temp.:
30°C (hold 1.0min.) to
180°C@ 10°C/min. (hold 5min.)
Flow rate:
8.5mL/min.
Sample:
11ppbv in 1mL sample loop
Standards: Dry standardsweremade by adding 2mL of a 100ppm stock sulfur standard to each precleaned and evacuated canister, then
pressurizing to 30psigwith ultra-pure nitrogen.The resultant concentrations are listed inTable 1. Humidified standardsweremade by injecting
100µL deionizedwater into the evacuated canisters prior to adding 2mL of stock standard.This produced 50%RH.
Dry SilcoCan
™
(n=18)
HumidifiedSilcoCan
™
(n=5)
Electropolished (n=2)
●
◆
▲
Time (Days)
Time (Days)
Time (Days)
Time (Days)
Time (Days)
Percent Recovery
Percent Recovery
Percent Recovery
Percent Recovery
Percent Recovery
2
H S
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10 ppbv COS
11 ppbv H
2
S
11 ppbvMethyl Mercaptan
11 ppbv Dimethyl Disulfide
11 ppbv Ethyl Mercaptan
tech
tip
AlternativeAnalytical
Techniques
Trace level sulfur compounds
also can be analyzed using
Restek’s Rt-XLSulfur
™
packed
ormicropacked columns.The
specially designed packing
material is optimized for low
ppbv sulfur compoundanalysis.
For an example chromatogram,
visit ourwebsite and enter
GC_PC00436 in the search
function.
