Passive/Diffusive Sampling

Passive/diffusive sampling relies on the unassisted molecular diffusion of gaseous analytes through a diffusive surface onto an adsorbent. Unlike active sampling, passive samplers require no electricity (expensive pumps), have no moving parts, and are simple to use (no pump operation or calibration). After sampling, the adsorbed analytes are desorbed off the adsorbent by solvent or thermal desorption.

Benefits of passive/diffusive sampling:
  • Compact, portable, unobtrusive, and inexpensive
  • Offers indication of average pollution levels over time periods of 8 hours to weeks/months
  • Requires no supervision, is non-flammable, and noiseless
  • Low cost allows for sampling at multiple locations (e.g., for highlighting pollution "hotspots"; or determining long term data trends in a specific geographical area)
  • Amenable to personal monitoring (breathing zone), indoor air analysis, and outdoor ambient air analysis