What is radiello^® diffusive sampling?

In the mid 1990's, Dr. Vincenzo Cocheo, director of the Fondazione Salvatore Maugeri, Padova, Italy, in collaboration with the European Commission's Joint Research Center and other institutions, developed and patented a revolutionary diffusive/sampling design: Radial symmetry now registered trademarked as radiello (Figure 1). It consists of a radial diffusive body made of porous polypropylene in which a cartridge with adsorbent is positioned. The adsorbent bed is selected for application and can consist of a pure adsorbent material or a chemically coated support. Due to this symmetry analytes can access the adsorbent material throughout the 360° surrounding diffusuive barrier/body resulting in a significant higher uptake rate. By virtue of radial symmetry, the uptake rates with the same dimensions, radiello's are at least three times higher than for any axial diffusive sampler (Figure 2).

Figure 1. Radial Design of radiello

Figure 2. Uptake/Sampling rates are higher for radial samplers than axial (e.g. Benzene @25°C <10mL/min vs. >70mL/min)

Due to the tortuous nature of the diffusive path inside the micro-porous diffusive membrane, the uptake rate is not affected by wind or air currents. The stiffness of the diffusive wall and cartridge, together with the close tolerances characterizing all of the radiello^® components, greatly reduces uptake rate variation. The uptake rates are not calculated, but are experimentally measured in a controlled atmosphere chamber over a wide range of concentration, temperature, relative humidity, air speed, and with and without interferences. The high capacity of the cartridge adsorbents provide a high capacity and minimal reverse diffusion.

Figure 3. Atmospheric Chamber Used to Measure Uptake Rates for radiello^® Cartridge

Features and Benefits of radiello^® Samplers

• The radiello design offers high uptake rates resulting in faster sampling
• Greater adsorbent capacity offers minimal reverse diffusion and greater uptake rate consistency resulting in more reproducible results.
• All uptake rates are precisely measured (not calculated) resulting in more precise measurements.
• The water repellent diffusive body makes radiello amenable to bad weather
• All cartridge adsorbents undergo a complex conditioning and QC procedure resulting cartridge background levels three times lower than instrument noise.
• The combination of low detection limits, high uptake rates and high capacity allowing for sampling time ranges from 15 min. to 30 days (1 ppb – 1000 ppm).
• Other benefits include, but are not limited to:
  • Predominately solvent/chemical desorption which does not require thermal desorption equipment
  • Amenable to thermal desorption & GC/MS with low interferences resulting in precise and very sensitive measurements
  • Touch and chemically inert making the sampler robust in use
  • Reusable hardware for more economic sampling
  • Available accessories (shelter) for ambient air analyses making radiello samplers amenable for a wide range of application areas