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Field Evaluation of Diffusive Samplers for Indoor Air VOC Measurements

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Field Evaluation of Diffusive Samplers for Indoor Air VOC Measurements AIHce 2011 Heidi Hayes, Technical Director Robert Mitzel, Vice-President Business Development – PowerPoint PPT presentation

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Title: Field Evaluation of Diffusive Samplers for Indoor Air VOC Measurements


1
Field Evaluation of Diffusive Samplers for Indoor
Air VOC Measurements
  • AIHce 2011
  • Heidi Hayes, Technical Director
  • Robert Mitzel, Vice-President
  • Business Development

1201
2
Outline
  • Introduction
  • Study Objectives
  • Sampler Selection
  • Field Sampling
  • Results
  • Conclusions

3
Conventional Air Sampling
Summa Canisters
Pumped Sorbent Tubes
  • Possible equipment failure
  • Requires experienced field sampler
  • Short duration (24 hours)
  • Expensive to ship
  • Requires experienced field sampler
  • Short duration (8 hours)
  • Sorbent type and sample volume selection is
    critical

4
Passive Sampling
  • Practical Advantages
  • Reliable deployment with little training required
  • Unobtrusive
  • Inexpensive to ship
  • Technical Advantages
  • Capable of generating trace level RLs
  • Long-term time-integrated measurements

More representative indoor air concentrations and
increased sensitivity are advantageous to health
risk assessments.
5
Passive Sampling Concepts
Measured in lab
Analytical Result (µg)
1000 mL 1L
1000 L m3
X
X
Concentration (µg/m3)
Uptake Rate (mL/min)
Sampling duration (min)
X
Recorded in the field
Available in literature Dependent on Sampler
Geometry
6
Project Objectives
  • Sample integration of 1 to 7 days
  • Measurement of a wide VOC suite
  • Petroleum and chlorinated compounds
  • Reporting limits comparable to TO-15 SIM (0.1
    µg/m3)
  • Measured concentrations correlate with TO-15

7
Passive Samplers
Sampler Geometries
Tube
Membrane
Radial
Badge
Analytical Sensitivity
Sorbent
Sampling Rate
Solvent
SKC 575 3M OVM
Radiello130
WMS- Charcoal
Thermal Desorption
SKC ULTRA
Radiello145
WMS- TD
ATD
Lowest
Highest
8
Passive Samplers
Sampler Geometries
Tube
Membrane
Radial
Badge
Sorbent
Solvent
Radiello130
Thermal Desorption
SKC ULTRA
Radiello145
9
Field Sampling Case 1
  • Indoor air samples collected
  • Duration 3, 4, and/or 7 days
  • Concurrent deployment
  • Radiello 130 Charcoal
  • Radiello 145 TD Sorbent
  • ULTRA III TD sorbent

10
Results
Good comparability was observed when detections
on each sampler were sufficiently above their
respective reporting limits.
11
Results
  • ULTRA III 5-20 times greater sensitivity than
    the RAD-Charcoal.
  • ULTRA III had validated sampling rates for
    chlorinated breakdown products whereas RAD-TD
    required estimated rates.
  • Diffusive adsorption on the RAD-TD sorbent did
    not behave as predicted for these light VOCs
    (chloroform, 1,1-DCE) resulting in low bias.
    Stronger TD sorbent is required for these VOCs.

12
Results
  • One indoor air location was severely impacted
    with chlorinated solvents (100 to 10,000 µg/m3)
  • Sampling duration was 3 days.
  • Both Radiello-TD and ULTRA III exceeded capacity
    TD-GC/MS.
  • Radiello-Charcoal had a higher capacity, and
    solvent extraction allowed for easy dilutions.

13
Field Sampling Case 2
  • Indoor air samples collected
  • 13 sites
  • Concurrent TO-15 cans ULTRA III
  • Chlorinated solvents,petroleum products
  • 1 to 3 day duration

14
Results
Strong correlation between ULTRA III and TO-15
concentrations across 3 orders of magnitude and
at concentrations lt0.1 µg/m3
15
Conclusions
  • Each passive sampler evaluated provided
    quantitative VOC indoor air measurements for TCE
    and PCE over a period of up to 7 days.
  • The larger surface area of charcoal provided an
    advantage over TD-sorbents when sampling high
    concentrations over multiple days.

16
Conclusions
  • ULTRA III-TD and Radiello-TD provide greater
    sensitivity than the Radiello-Charcoal over the
    1-7 day period.
  • ULTRA III-TD provides a wider range of VOCs than
    Radiello-TD.
  • ULTRA III has a built-in blank correction
    allowing for improved accuracy at trace levels.
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