Optimizing Sampling and Analytical Parameters for Soil Vapour Samples using Automated Thermal Desorption / Gas Chromatography / Mass Spectrometry (ATD/GC/MS) Stephen Varisco, Technical Manager, CARO Analytical Services Lee Marotta, GC/MS Product Specialist, PerkinElmer LAS Miles Snow, GC/MS Product Specialist, PerkinElmer LAS Copyright 2009 PerkinElmer LAS and CARO Analytical Services, Inc.
Outline Objective: Soil Vapour Tube 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
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/m 3 (dry cleaning site) Benzene 1.5 ug/m 3 (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 Air Toxics Charcoal Tubes 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
State 1: Sample Tube Desorption IS and/or surrogate spike Optional inlet split Desorb flow Temperature Flow Time xxxxxx Peltier-cooled trap no need for liquid cryogen Inert gas
Stage 2: Transfer of Sample to Instrument Optional outlet split or Recollect on same tube or new tube Column Flow = 2.5mL/min Recollect Flow = 10mL/min %Recollected = 80% GC Detector heated trap Carrier gas in Analytical column
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 Linearity AT_032609_09 100 Mass Range: 35 to 300 AMU Conc: 20ng on Column Broad Boiling Point Range: Chloromethane to Naphthalene 22.97 23.59 27-Mar-2009 + 01:37:40 25.82 Scan EI+ TIC 3.23e8 21.34 15.02 19.51 18.73 18.42 20.52 21.28 25.66 26.18 % 17.81 26.30 10.95 2.97 5.57 7.99 9.53 6.99 8.32 8.89 7.33 10.75 12.62 12.33 13.58 14.59 15.37 16.74 19.72 23.89 3.27 4.02 4.69 5.00 5.67 6.55 6.01 10.34 11.16 15.65 16.02 13.14 0 2.77 4.77 6.77 8.77 10.77 12.77 14.77 16.77 18.77 20.77 22.77 24.77 26.77 Time
Tube Design and Adsorbent Optimization
Thermal Desorption Tube Multiple Adsorbents accommodate wide boiling point range sample Weaker Adsorbent Strong Adsorbent Strongest Adsorbent Sample Stream Carrier for Desorption DESORB ADSORB
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 Instrumentation: PerkinElmer TurboMatrix 650 Thermal Desorber PerkinElmer Clarus 600 GC/MS Compound Class # Comp Precision (%RSD) Dynamic Range Reporting Limit Outliers n=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 CHCl 3 =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
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 100 100 PAH Compounds % Carryover (very low) 1-Methyl Napthalene 0.3 Anthracene 0.2 Fluorene 0.6 Phenanthrene 1.2 AT_040809_07 % 0 AT_040809_11 % 0 Spiked Tube 10.59 Re-inject of spiked tube 11.87 12.53 13.99 09-Apr-2009 + 14:13:55 Scan EI+ 153+166+142+178 2.06e8 9.44 9.94 10.44 10.94 11.44 11.94 12.44 12.94 13.44 13.94 14.44 14.94 15.44 14.07 Scan EI+ 153+166+142+178 2.06e8 Time
Tube Robustness Diesel Carryover <1% new 650_040809_08 100 10,000ng Diesel spiked tube 24.55 25.87 26.98 27.96 08-Apr-2009 + 16:57:46 Scan EI+ TIC 6.96e8 % 22.91 20.72 24.01 17.71 21.34 22.37 0 new 650_040809_10 100 Reanalysis of this tube to determine Carryover 25.54 26.78 28.06 28.83 29.64 Scan EI+ TIC 6.96e8 % 0 28.82 27.95 9.00 11.00 13.00 15.00 17.00 19.00 21.00 23.00 25.00 27.00 29.00 31.00 33.00 Time
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 Nitrogen carrier gas Spiked Clean water bubbler Sample Tube spiked 300ng of 79 components Total = 23,700ng on tube Passed humidified N 2 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 VOC gasses: 10L of sample 70% humidity Component % BT Dichlorodifluoromethane 1.0 Chloromethane 5.4 Vinyl Chloride nd Bromomethane nd Chloroethane nd Trichlorofluoromethane nd
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? Mass Spectrometer (detector) problems Signal quenching Increased maintenance Poor chromatography Can cause false negatives AT_050609_BT_14 100 3.05 With Dry Purge 3.54 Water 07-May-2009 + 03:49:07 Scan EI+ Sum 1.85e7 AT_050209_BT_22 100 No Dry Purge 2.96 3.04 3.22 3.38 3.49 3.67 3.78 3.86 3.97 4.60 4.21 4.30 4.54 03-May-2009 + 04:04:33 Scan EI+ Sum TIC 1.59e9 1.85e7 4.81 4.96 5.02 5.51 5.25 5.605.76 5.90 5.96 6.12 6.25 6.42 6.50 2.63 2.11 2.22 2.43 2.82 3.26 4.25 2.95 3.70 % 6.43 % 3.49 4.04 3.02 3.22 4.22 3.66 5.16 5.96 6.11 1 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 4.98 Time 01 Time 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 6.00 6.50 7.00
Real World Sample Petroleum Contamination (Tank Pull Site) Abundance 1700000 Component Result (ug/m3) 1,2,4-trimethylbenzene 72.7 1,3,5-trimethylbenzene 16.2 Benzene 1.6 Dichlorodifluoromethane 9.1 Ethylbenzene 12.3 Naphthalene 20.9 Tetrachloroethene 9.9 Toluene 45.7 900000 Trichlorofluoromethane 1.2 800000 Xylenes (total) 80.0 nc6-nc13 9950 1600000 1500000 1400000 1300000 1200000 1100000 1000000 700000 TIC: 090515a-39.D 600000 500000 400000 300000 200000 100000 Time--> 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 26.00 28.00 nc6 nc10 nc13
Summary Thermal Desorption Technology Tubes well-suited for vapour intrusion investigations Instrumentation Advancements Analytical Integrity Team developed new Thermal Desorption Tube that Achieves 1. Broadest Analytical Range 2. Protection of the Strong Adsorbents 3. Good Safe Sampling Volumes 4. 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.