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Stephen Varisco, Technical Manager, CARO Analytical ServicesLee Marotta, GC/MS Product Specialist, PerkinElmer LASMiles Snow, GC/MS Product Specialist, PerkinElmer LAS
Optimizing Sampling and Analytical Parameters for Soil Vapour Samples using Automated Thermal
Desorption / Gas Chromatography / Mass Spectrometry (ATD/GC/MS)
© Copyright 2009 PerkinElmer LAS and CARO Analytical Services, Inc.
Outline
Background• CARO Analytical Services• Soil Vapour Regulations
Thermal Desorption Technology• Advantages• Operation
Tube Design and Adsorbent Optimization• Limitations of current tubes for soil vapour samples• Objectives of new tube
New Tube Performance Characteristics
Objective: Soil Vapour Tube
Background information on CARO Analytical Services
British Columbia based• Full Service Environmental Testing Capabilities
Technical Leadership in Soil Vapour• Co-authored BC SV Reference Methods• ISO 17025 Accreditation for SV (www.cala.ca)
Client Collaboration• Knowledgeable & Accessible Staff• Equipment Rentals, Client Training
SR&D Projects• VOC Artifacts in Tubing (www.caro.ca/soilvapour)• Custom TD Tube Development• VOC Sorption on Tubing – in progress
Regulatory Background
23 US States regulate Soil Vapour Intrusion
British Columbia Contaminated Sites Regulations, Schedule 11• Effective January 1, 2009• 118 regulated parameters: >90% via TD• Stringent regulations
– Trichloroethene (TCE) – 1.0 ug/m3 (dry cleaning site)– Benzene – 1.5 ug/m3 (gasoline site)
Why is soil vapour important?• Protection of Human Health
Test water and soil first? Or … Test vapour first?
Advantages and Operation of Thermal Desorption
Technology
Advantages of Thermal Desorption Technology
1. Established methodology
2. Convenient transport
3. Easy to clean … immediate reuse …fast turnaround
4. Cost effective
5. Large sample volumes
6. Suitable for non-polar and polar compounds
7. Inherent Water Management
8. Enables Recollection to preserve sample
Air Toxics ≠ Charcoal Tubes
State 1: Sample Tube Desorption
xxxxxx
OptionalOptionalinlet splitinlet split Desorb flowDesorb flow
PeltierPeltier--cooled trap cooled trap no need for liquid cryogenno need for liquid cryogen
IS and/or surrogate spike
– Temperature
– Flow
– Time
Inert gas
Stage 2: Transfer of Sample to Instrument
GCGCDetectorDetector
Carrier gas inCarrier gas in Analytical columnAnalytical column
Optional ‘outlet’ split or Recollect on same tube or new tube
heated trapheated trap
Column Flow = 2.5mL/min
Recollect Flow = 10mL/min
%Recollected = 80%
Optimizing Sample Integrity with Thermal Desorption
Automatic Internal Standard addition
Recollection onto the same tube or new tube
Automated Leak Checking
Impedance Testing
Excellent Water Management
Total Ion Chromatogram of a 74 TO-15 and TO-17 Component Mix
27-Mar-2009 + 01:37:40Linearity
2.77 4.77 6.77 8.77 10.77 12.77 14.77 16.77 18.77 20.77 22.77 24.77 26.77Time0
100
%
AT_032609_09 Scan EI+ TIC
3.23e8
21.34
19.5115.02
10.95
9.537.996.99
5.57
2.97
4.69
3.27
4.02
5.00
5.676.55
6.01
7.338.898.32 10.75
10.34
12.6212.33
11.16
13.58
13.14
14.59
18.73
18.42
17.81
15.37
16.74
15.65
16.02
20.52
19.72
21.28
23.59
22.97
25.82
25.66
23.89
26.18
26.30
Mass Range: 35 to 300 AMU
Conc: 20ng on Column
Broad Boiling Point Range: Chloromethane to Naphthalene
Tube Design andAdsorbent Optimization
Thermal Desorption Tube
Multiple Adsorbents accommodate wide boiling point range sample
SampleStream
ADSORBDESORB
StrongestAdsorbent
WeakerAdsorbent
StrongAdsorbent
Carrier for Desorption
Goal – Optimize a Tube for Soil Vapour Intrusion Sampling
Soil vapour differs from other air sampling applications:
• Higher moisture• Greater analyte range• Wider concentration range
Limitations of current industry-standard sorbent tubes:
• Lack of a weak adsorbent prevents release beyond nC12• Ensure Safe sampling volumes for the low boilers
Characteristics of New Thermal Desorption Tube
Broadest Analytical Range• dichlorodifluoromethane to phenanthrene• nC3 – nC22+
Protects the Strong Adsorbents• Prevents irreversible adsorption • Clean after one desorption cycle
Good Safe Sampling Volumes
Optimal Water Management
Soil Vapour Intrusion Tubes Performance Characteristics
Precision, Linearity (average for Class) and Reporting Limits
Compound Class # Comp Precision (%RSD) Dynamic Range Reporting Limit Outliersn=8 0.2 to 200 ng 10 liter sample (FS) on RL
Gasses 6 6.9% 0.9952 0.05 ug/m3
non-Aromatic Halogens 33 2.7% 0.9985 0.02 ug/m3 CHCl3=0.05ppb
Aromatics 15 1.4% 0.9995 0.02 ug/m3
Halogenated Aromatics 9 1.4% 0.9997 0.02 ug/m3
Others 10 2.7% 0.9965 0.05 ug/m3
Instrumentation:
PerkinElmer TurboMatrix 650 Thermal Desorber
PerkinElmer Clarus 600 GC/MS
Recovery Results EXCELLENT
79 components investigated • 400ng VOC mix + 250ng PAH• Range: difluorodichloromethane
to phenanthrene
Recovery procedure• Analyzed spiked tube• Analyzed blank tube• Re-analyzed spiked tube which
should be clean
Non-detectable carryover• Slight carryover of 4 heaviest
PAHs• Significantly below method
criterion
PAH Compounds % Carryover(very low)
1-Methyl Napthalene 0.3Anthracene 0.2Fluorene 0.6Phenanthrene 1.2
09-Apr-2009 + 14:13:55
9.44 9.94 10.44 10.94 11.44 11.94 12.44 12.94 13.44 13.94 14.44 14.94 15.44Time0
100
%
0
100
%
AT_040809_07 Scan EI+ 153+166+142+178
2.06e810.59
11.8712.53 13.99
14.07
AT_040809_11 Scan EI+ 153+166+142+178
2.06e8
Spiked Tube
Re-inject of spiked tube
Tube Robustness – Diesel
Carryover <1%
08-Apr-2009 + 16:57:46
9.00 11.00 13.00 15.00 17.00 19.00 21.00 23.00 25.00 27.00 29.00 31.00 33.00Time0
100
%
0
100
%
new 650_040809_08 Scan EI+ TIC
6.96e826.98
25.87
24.55
22.91
20.72
17.71 22.3721.34
24.01
25.54 26.78
27.96
28.83
28.0629.64
new 650_040809_10 Scan EI+ TIC
6.96e8
28.8227.95
10,000ng Diesel spiked tube
Reanalysis of this tube to determine Carryover
What is Breakthrough?
Goal: Regulated compounds do not break through
EPA TO-17: “The volume sampled when the amount of analyte collected in a back-up sorbent tube reaches a certain percentage (typically 5%) of the total amount collected by both sorbent tubes”
Calculation: BT / (BT+spiked)*100%• BT = concentration of back tube• Spiked = concentration of front tube
Safe Sampling Volume (SSV): 2/3 of Breakthrough Volume
Assessing breakthrough in the real-world:• Sampling in series• Sampling in parallel (distributed volume pairs)
Manifold used for determining breakthrough & moisture retention
Injector
water bubblerwater bubbler
Nitrogen “carrier” gas
Spiked Clean
Sample Tube spiked• 300ng of 79 components• Total = 23,700ng on tube• Passed humidified N2 through tube
– flow rate = 100mL/min– Time = 100min– Mimic 10L sampling– All studies performed in triplicate
Slight Breakthrough of only two Components out of 79 VOCs
Component % BT
Dichlorodifluoromethane 1.0Chloromethane 5.4Vinyl Chloride ndBromomethane ndChloroethane ndTrichlorofluoromethane nd
VOC gasses:
•10L of sample
•70% humidity
Water Management
Methods of Water Removal
1. Nafion Drier / Desiccants
Polar Compounds Removed - Cannot be used
2. Hydrophobic adsorbents
3. Minimize sampling volumes while maintaining regulated detection limits
4. Dry Purging
Typically not required for indoor air
Why Remove Moisture?
03-May-2009 + 04:04:33
2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 6.00 6.50 7.00Time0
100
%
AT_050209_BT_22 Scan EI+ Sum
1.85e7
6.43
3.49
3.023.22
4.223.66 5.165.96 6.11
03-May-2009 + 04:04:33
2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 6.00 6.50 7.00Time1
100
%
AT_050209_BT_22 Scan EI+ TIC
1.59e93.38
3.223.042.96
2.632.432.222.11 2.82
3.673.49 3.78 3.864.603.97
4.21 4.544.30 5.604.964.81 5.515.255.02 6.125.965.905.76 6.25 6.42 6.50
07-May-2009 + 03:49:07
2.18 2.38 2.58 2.78 2.98 3.18 3.38 3.58 3.78 3.98 4.18 4.38 4.58 4.78 4.98Time1
100
%
AT_050609_BT_14 Scan EI+ Sum
1.85e73.543.05
2.95
3.264.25
3.70
4.04
Water
Mass Spectrometer (detector) problems• Signal quenching• Increased maintenance
Poor chromatography • Can cause false negatives
With Dry PurgeNo Dry Purge
Real World Sample – Petroleum Contamination (Tank Pull Site)
2.00 4.00 6.00 8.00 10.0012.0014.0016.0018.0020.0022.0024.0026.0028.00
100000
200000
300000
400000
500000
600000
700000
800000
900000
1000000
1100000
1200000
1300000
1400000
1500000
1600000
1700000
Time-->
Abundance
TIC: 090515a-39.D
nC6 nC10 nC13
Component Result (ug/m3)1,2,4-trimethylbenzene 72.71,3,5-trimethylbenzene 16.2Benzene 1.6Dichlorodifluoromethane 9.1Ethylbenzene 12.3Naphthalene 20.9Tetrachloroethene 9.9Toluene 45.7Trichlorofluoromethane 1.2Xylenes (total) 80.0nC6-nC13 9950
Summary
Thermal Desorption Technology• Tubes well-suited for vapour intrusion investigations• Instrumentation Advancements → Analytical Integrity
Team developed new Thermal Desorption Tube that Achieves1. Broadest Analytical Range2. Protection of the Strong Adsorbents3. Good Safe Sampling Volumes4. Optimal Water Management
Presentation available for download at www.caro.ca or www.perkinelmer.com
Acknowledgements
Project Team:
CARO Analytical Services:• Stephen Varisco, Technical Manager• Luba Tsurikova, Senior Analyst• Patrick Novak, Business Manager• Brent Mussato, President
PerkinElmer:• Lee Marotta, Senior Product Specialist• Miles Snow, Senior Product Specialist
© Copyright 2009 PerkinElmer LAS and CARO Analytical Services, Inc.
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