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.