Diffusive Sampling Device

The POD sampler was designed to improve sampling and storage while remaining compatible with thermal desorption analysis systems. Design improvements included: (i) increasing the relative diffusion surface with the adsorbent by combining axial and radial diffusion; (ii) providing a dynamic range of diffusion rates through application of diffusion bodies with different porosities; (iii) reducing blank levels by minimizing the amount of adsorbent within a certain analytical range; (iv) enabling a high level of reusability by using inert material that can be cleaned with short temperature treatment; (v) providing a strong hermetic seal for storage during transport; and (vi) availability of different porous materials, which can enhance durability (i.e., stainless steel diffusive bodies), act as an scrubber for reactive compounds (i.e., bronze diffusive bodies) or provide inert sampling (i.e. Teflon).

Application areas

Ambient air sampling, workplaces and indoor pollution sampling, exposure sampling

Innovative aspects and main advantages

• The sampler is easy to handle and the adsorbent cartridge can be used in current thermal desorption systems
• The sampler use minimum amount of adsorbent by taking advantages of the highest sensitivity of the thermal desorption analysis.
• The accurate sampler design provides a high reproducibility in replicated samples.
• The sampler combines axial and radial diffusion
• The sampler has been characterized by a low effect of environmental variables on the sampling rate (i.e. wind velocities, temperature).
• The POD sampler has been validated for the measurement of volatile organic compounds
• Expanded uncertainties for analysis of benzene in ambient air has been calculated to be under 20 %.
• The sampler has also been used for the analysis of HCB and lighter PAHs