Transcript No Slide Title

Effects of Aging on Surface Inertness
and Analyte Recoveries in SUMMA
Passivated and Fused Silica Lined
Canisters
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Objectives
• Test Canisters from 4 Manufacturers for the
Relative Aging Effects of Repeated Sampling on
TO14 Standard Recoveries
• Repeat Test After Exposure to 1% Ozone for 8
hours
• Test Aged Canisters using a Spectra Gas TO15
Mixture
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Canisters in Study
• 4 Manufactures - 2 SUMMA, 2 Fused Silica Lined
• 2 Cans from Each Manufacturer
• SUMMA cans labeled S1 - S4
• Fused Silica Lined Canisters Labeled FS1-FS4
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Silonite Coated 6L Canisters
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SiloniteTM Coating of Canisters
• Improves Recovery of
Reactive Compounds
• Increases Range of
Compounds Amenable
to Canister Sampling
and Analysis
• Compounds Containing:
– Sulfur
– Nitrogen
– Oxygen
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40 Day Formaldehyde Stability in Silonite Coated MiniCan
Analysis of Cylinder - 9 December 1999
2.52 ppm
2.65 ppm
2.54 ppm
Analysis of Mini Canister #1086 - 10 December 1999
2.56 ppm
2.44 ppm
Analysis of Mini Canister #1087 - 10 December 1999
2.57 ppm
2.56 ppm
Let time pass....
Analysis of Mini Canister #1086 - 20 January 2000
2.46 ppm
2.53 ppm
Analysis of Mini Canister #1087 - 20 January 2000
2.37 ppm
Data Courtesy of
Dr. Daniel Riemer,
NCAR
2.47 ppm
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10 PPB TO14 Std
1-Day TO14 Stability Test @ 10PPB
5 PSIG
Holding Time - 1 Day
Abun dan ce
A bu nd an ce
TI C: 9912 1002. D
TI C: 9912 1004. D
400 0000
400 0000
350 0000
350 0000
300 0000
300 0000
250 0000
250 0000
200 0000
200 0000
150 0000
150 0000
100 0000
100 0000
500 00 0
50 000 0
5.0 0
10 .0 0
15. 00
2 0. 00
25. 00
Ti m e-- >
5.0 0
10 .00
15. 00
2 0. 00
25. 00
30 .0 0
T im e ->
New Silonite Canister
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30 .0 0
Used SUMMA Canister
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Clean up Test
Blank Test After 100 PPB TO14 Exposure
New Silonite Canister
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Used SUMMA Canister
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Canister Study
• Test all Canisters at the Beginning of Study
– Fill Canister with 10 PPB TO14 Mix
– Equilibrate 1 Day and Analyze
• Clean All 8 Canisters Together (3 cycles at 100 C)
• Fill Canisters with Ambient Air using Glass
Filtered Grab Sampler
• Wait 1 Day, then Repeat Cleaning
• Perform Operation 30 Times
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8 Canister Cleaning System
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Glass Filtered Grab Sampling
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Standard Introduction and Analysis
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7100 3-Stage Preconcentrator
•Automates the GC
analysis of gas phase
samples
•Complete heating of
sample flow path. Easily
accessed for trap and
tubing replacement
•Multiple trapping
stages allow matrix to be
eliminated before GC
injection
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7100 Preconcentrator
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7100 Preconcentration and Matrix Management
3-Stage Preconcentration
MFC
PUMP
N2, O2
H20, CO2
Helium Carrier
Helium
To
GC
Focuser
Sample
Headspace
Internal
Standard
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Calibration Sample
Standard
Glass Beads
Tenax
Cryogen in
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Fast Injection and Proper Water Management
Minimizes Tailing of Polar Compounds
26000
75000
25000
24000
70000
65000
60000
55000
Methanol
m/z 31
3.67 min.
0.49 ppb
50000
23000
22000
21000
20000
19000
18000
Column: HP1,
60m, 0.32mm ID,
1um film.
Flow rate: 1.5 ccm
17000
16000
45000
Ethanol
m/z 45
4.35 min
0.17 ppb.
Carrier: He
15000
14000
40000
13000
12000
35000
11000
30000
10000
9000
25000
8000
7000
20000
6000
5000
15000
10000
4000
3000
2000
5000
1000
0
3.50 3.55 3.60 3.65 3.70 3.75 3.80 3.58 3.90 3.95
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New SILONITE Coated Canister Before Study
Concentration - 10 PPB
Pressure - 10 PSIG
Volume - 400 CC
Water Management - Microscale Purge and Trap
Instrumentation 7100/5973
Column - DB1
Starting Temperature - 35 deg. C
Scan - 30-185, 6 min, then 34-270 amu
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10 PPB/10 PSIG TO14 , 1 Day Stability - SUMMAs
S1
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S3
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10 PPB/10 PSIG TO14 , 1 Day Stability - FSL Cans
FS 1
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FS 3
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10 PPB/-4 PSIG TO14 , 1 Day Stability - SUMMAs
S1
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S3
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10 PPB/-4 PSIG TO14 , 1 Day Stability - FSL Cans
FS 1
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FS 3
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10 PPB/-4 PSIG TO15 , 1 Day Stability - SUMMAs
FS 1
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FS 3
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10 PPB/-4 PSIG TO14 , 1 Day Stability - FSL Cans
FS 1
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FS 3
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Possible Reasons for Poor Recoveries in Canisters
• Coating or Surface Treatment was not Initially
Inert
• Welds have Active Surfaces
• Contaminants have been Introduced
– Particulates
– Semi-Volatiles
– Reaction Products
– Dirt
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Pressurized Field Sampling
• Causes Condensation of Water in transfer lines
and Canisters
• Water can Promote Polymerization Reactions
• White Deposits Found in Bottom of Canisters
which were Repeatedly Sampled to Positive
Pressure in the Field
• Not Required for Today’s Samplers / Analyzers
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Removing Heavy Contaminants from Canisters
• Evacuate Canisters
• Use Vacuum to Draw in 200 cc of DI Water
• Heat to 60 deg. C for 8 Hours (or Overnight)
• Pressurize Cans to 20 psig
• Shake Canister Well, Invert, Blow out Water
• Perform Normal Cycle Cleaning
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Conclusion
• Both SUMMA and Fused Silica Lined Canisters Showed no
Detectable Loss of Inertness after 30 Samplings of Ambient
Air
• Although Individual Recoveries of TO15 Standard Varied,
Both Canister Types Provided Good Recoveries of Spectra
Gas TO15 Compounds
• Ozone Exposure did not Change Recoveries
• Canister Cleanliness is Extremely Important. Canisters
Should be Checked Regularly for Analyte Recovery
• If Recoveries are Found to be Low, Enhanced Cleanup
Techniques are Available to Remove Adsorbing / Absorbing
Contaminants
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