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Field Evaluation of Diffusive Samplers for Indoor Air VOC Measurements

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Presentation on theme: "Field Evaluation of Diffusive Samplers for Indoor Air VOC Measurements"— Presentation transcript:

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.

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