USING DIFFUSIVE SAMPLERS FOR MONITORING FOR PPB LEVELS OF VOLATILE ORGANIC COMPOUNDS IN AIR

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USING DIFFUSIVE SAMPLERS FOR MONITORING FOR PPB
LEVELS OF VOLATILE ORGANIC COMPOUNDS IN AIR

• Linda S. Coyne
• Cindy A. Kuhlman
• Bruce J. Pacolay

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HISTORY OF DIFFUSIVE SAMPLERS

• Diffusive samplers were developed in the late
  1970s
• IH Professionals were skeptical about their
  ability to accurately monitor concentrations in
  the workplace
• Face Velocity
• Reverse Diffusion
• Sampling Rate

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BADGE SUPPORTERS

• Testing continued on many compounds
• Recognition of their value and potential in the
  workplace

• Advantages
• Required little training
• Small and quiet
• Unobtrusive to the worker

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MAJOR DEVELOPMENTS

• OSHA PUBLISHED FIRST VALIDATED METHOD IN 1998
• THEIR STUDIES INDICATED THAT DIFFUSIVE SAMPLERS
  COULD ACCURATELY MONITOR VOCS IN THE WORKPLACE
• PUBLISHED SEVERAL METHODS
• BENZENE
• MEK AND MIBK
• XYLENES

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CONTINUING DEVELOPMENTS

• AS BADGES WERE ACCEPTED, THEY WERE INVESTIGATED
  FOR OTHER DISCIPLINES
• Indoor Air Quality
• Ambient Air

• THESE DISCIPLINES WERE QUITE DIFFERENT FROM
  INDUSTRIAL HYGIENE
• Low face velocity
• High face velocity
• Extended sampling times
• Desorption efficiency at low microgram levels

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ENVIRONMENTAL PROTECTION AGENCY

• PUBLISHED AN ARTICLE IN DECEMBER 1999 ON INDOOR
  AIR QUALITY
• EPA LISTED THE 10 MOST FREQUENTLY MEASURED VOCs
  IN OFFICE BUILDINGS
• Dichlorodifluoromethane ? Trichloroethane
• Toluene ? Ethanol
• Acetone . ? 2-Propanol
• n-Hexane ? Xylenes
• Benzene ? Chloromethane

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TESTING PLAN

• Extend the original validation to include
  parameters typical of indoor and ambient air
• 24-hour sampling
• Lower concentration range 10-150 ppb
• Face velocity 10-20 cm/sec
• Desorption efficiency 0.2 to 10 micrograms
• Long-term reverse diffusion 1-5 days

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DIFFUSIVE SAMPLERS TESTED

• 575-001
• -350 mg of activated charcoal
• -In-situ desorption
• -Analysis by GC/FID
• -Detection limits in the 200-500 ng range,
  depending on chemical

• 590-100(Ultra)
• -265 mg of Tenax TA
• -Thermal desorption with heated nitrogen
• -Analysis by GC/FID or GC/MS
• -Detection limits in the
• 1-2 ng range

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575-001 Sampler
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590-100 Sampler
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VAPOR GENERATION APPARATUS
Syringe Pump
Flow
Air Compressor
Drier
Charcoal Trap
Humidifier
Flow
Exposure Chamber
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DETECTION LIMIT IN PPB(BASED ON A 24-HOUR SAMPLE)

• 575-001 SAMPLER
• TOLUENE 3 PPB

• 590-100 SAMPLER
• TOLUENE 10 PPT

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DESORPTION EFFICIENCIES FOR THE 575-001 SAMPLER
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DESORPTION EFFICIENCIES FOR THE 575 SERIES BADGES
FOR ACETONE, HEXANE, AND p-XYLENE
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SAMPLING RATES(SR) FOR 24-HOUR SAMPLING
OFACETONE, HEXANE, AND p-XYLENEON THE 575
SERIES PASSIVE SAMPLERS10-100 ppb, 80 RH, 25 C
a) Validated by either SKC Inc. or OSHA Salt Lake
Technical Center for 8 hour sampling of compounds
in air.
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SAMPLING RATES(SR) FOR 24-HOUR SAMPLING OF
BENZENE, TOLUENE, AND o-XYLENEWITH THE 590-100
ULTRA SAMPLER10-100 ppb, 80 RH, 25 C
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5-DAY REVERSE DIFFUSION DATA WITH THE 575 SERIES
PASSIVE SAMPLER RECOVERY
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REVERSE DIFFUSION EXPERIMENT FOR BENZENE AND
XYLENE WITH THE 575-001 SAMPLERMicrograms