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
Available in literature
Dependent on Sampler Geometry
Recorded in the field

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. Analytical Sensitivity
Passive Samplers
Sampler Geometries
Tube
Membrane
Badge
Radial
Analytical Sensitivity
Sorbent
Sampling Rate
Solvent
WMS®-
Charcoal
SKC 575
3M OVM
Radiello®130
Thermal
Desorption
ATD
WMS®- TD
SKC ULTRA
Radiello®145
Lowest
Highest

8. Passive Samplers Sampler Geometries Tube Membrane Badge Radial Sorbent
Solvent
Radiello®130
Thermal
Desorption
SKC ULTRA
Radiello®145

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 <0.1 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.