Soil Vapour Forum- Charcoal Tubes and Miscellaneous Sampling Methods - - PowerPoint PPT Presentation

soil vapour forum charcoal tubes and miscellaneous
SMART_READER_LITE
LIVE PREVIEW

Soil Vapour Forum- Charcoal Tubes and Miscellaneous Sampling Methods - - PowerPoint PPT Presentation

ANALYTICAL CHEMISTRY & TESTING SERVICES Soil Vapour Forum- Charcoal Tubes and Miscellaneous Sampling Methods Right solutions. presented by Kari Mulroy .Right partner ANALYTICAL CHEMISTRY & TESTING SERVICES Charcoal Tubes


slide-1
SLIDE 1

ANALYTICAL CHEMISTRY & TESTING SERVICES

Soil Vapour Forum- Charcoal Tubes and Miscellaneous Sampling Methods

presented by Kari Mulroy

Right solutions…. ….Right partner

slide-2
SLIDE 2

ANALYTICAL CHEMISTRY & TESTING SERVICES

Charcoal Tubes

slide-3
SLIDE 3

Charcoal Tubes

  • Active sampling with mechanical pumps
  • 15 minutes to 8 hours typical
  • Flow rate can vary, typically 200mL/min
  • Sample time and flow rate dependant on compound

and method selection

  • OSHA/NIOSH methods provide guidelines
  • Following these guidelines helps prevent breakthrough

problems & over saturation

  • Modifications to reference methods must be validated
slide-4
SLIDE 4

Charcoal Tubes

  • Charcoal extracted/desorbed in solvent

– Commonly carbon disulfide (CS2) but chosen according to compound of interest and method being run, i.e. NIOSH/OSHA methods – 1-2 µL injected into GC/FID or GCMS – 1/500th to 1/1000th of total sample analyzed

slide-5
SLIDE 5

Charcoal Tubes

  • DL & Sampling Volume Considerations

– DLs are dependant on total sampling volume (sampling time x flowrate). – Typical detection limits for discretes:

  • 1 ppmv for 15 minutes x 100 mL/min
  • 0.05 ppmv for 8 hours x 100 mL/min
  • Lower DLs achievable by GCMS

– Upper limits dependant on breakthrough volume and charcoal tube capacity

  • Lighter hydrocarbons breakthrough earlier
  • Upper limit ~10,000ppmv for 15 minutes x 100 mL/min,
  • r ~200 ppmv for 8 hours x 100 mL/min
slide-6
SLIDE 6

Charcoal Tubes

  • Advantages

– Reanalysis of samples is possible

  • Facilitates dilutions for high samples
  • Confirmation by alternate detector possible

– Easily transported – “Back” tube sampled for every sample

  • Breakthrough checks always possible

– Moisture is not typically a problem – Tubes and pumps are readily available – Sample stability (≥ 14 days) – Control capacity / max sampling volume by tube size selection – Lower cost method

slide-7
SLIDE 7

Charcoal Tubes

  • Disadvantages

– Less sensitive than some of other methods – Require higher sampling volume – Shorter list of applicable compounds than TO15/17 – Requires a pump in the field – Note: Speak to the lab about DL requirements. When applying potential attenuation factors charcoal may be appropriate.

slide-8
SLIDE 8

Miscellaneous Tubes - XAD

slide-9
SLIDE 9

Miscellaneous Tubes - XAD

  • PAHs may be sampled on XAD tubes using

NIOSH methods.

  • Achievable DLs vary with sampling volume.
  • Same advantages / disadvantages as

charcoal method.

slide-10
SLIDE 10

Miscellaneous Tubes - DNPH

slide-11
SLIDE 11

Miscellaneous Tubes - DNPH

  • Acetaldehyde and acrolein can be collected
  • n DNPH tubes.
  • Analyzed by NIOSH 2018 or EPA TO-11
  • Both methods require HPLC analysis and

typically have a DL of 0.5ug per tube.

  • Acrolein can be unstable on this media.
slide-12
SLIDE 12

Miscellaneous Media – Filter Cassettes / XAD / Silica Gel

slide-13
SLIDE 13

Miscellaneous Media – Treated Filters

  • Filter cassettes maybe used to collect some

compounds such as chlorine

  • Treated filter, analyzed by NIOSH 6011
  • Disadvantages:
  • Large air volume and flowrate required
  • Media is less readily available
slide-14
SLIDE 14

Miscellaneous Media – Impingers / Bubblers

slide-15
SLIDE 15

Miscellaneous Media – Impingers / Bubblers

  • Bubblers can be used as an alternate media

for some substances:

  • Acrolein can be collected by a modified CARB 430

which uses toluene in the bubbler to extract the reacted acrolein away from the DNPH solution.

  • Hydrogen Cyanide may be collected using a

bubbler, following NIOSH S288

  • Alternate method is NIOSH 7904 (soda lime tube)
slide-16
SLIDE 16

Miscellaneous Media – Impingers / Bubblers

  • Advantages*:
  • Typically used only where necessary
  • Disadvantages:
  • Equipment is fragile
  • Handling chemical solutions in the field
  • TDG issues

* In some cases, may be the only option to meet required detection limits.

slide-17
SLIDE 17

Questions?