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Products shown here are related to the application of thermal desorption for defence and forensic. Or find out more about defence applications and forensic applications.

Passive sampling

Passive sampling (diffusive sampling) onto sorbent media uses the principle of Fick’s first law of diffusion to target known sample environments. Using this approach, analytes migrate to the surface of a sorbent bed at a rate that depends on the conditions.

As no power source is required, passive samplers can be used for long-term, time-weighted-average monitoring to determine exposure levels in line with occupational health guidance. When used for environmental

air monitoring, their relatively low cost makes them suitable for large-scale deployment.

  • Axial diffusive samplers are used for measuring volatile organic compounds (VOCs) in air over a wide concentration range. Depending on the concentration of the target analytes, axial samplers are exposed for periods between 8 hours and 4 weeks.
  • Radial diffusive samplers are constructed so that the orientation of the diffusion path is parallel to the radius of the sorbent cartridge. They have a cylindrical diffusive surface area, and so have an effective sampling rate typically 100 times that of axial samplers. Because of this, radial samplers are often used for short-term deployment (4 hours to 1 week), and are not always suited to sampling high-concentration atmospheres.
  • Speciality passive samplers are available for certain non-volatile organic compounds.