Overview

Active Sampling
In active sampling, the air/gas sample is actively pumped or drawn into or through sampling media. Media can be filters and cassettes, or adsorbent tubes (including solvent desorption tubes and thermal desorption tubes). In addition to capturing analytes of interest from the air, the active sampling device must ensure minimal background interference, exhibit sufficient capacity or breakthrough volume for the intended application, and provide an acceptable pressure drop during sampling. Specialty tubes for mercury vapor sampling, color-indicating MSA/Auer detector tubes for direct concentration measurement of target analytes, and the ATIS adsorbent tube injector system complete the range of active sampling products.

Passive Sampling
Passive/diffusive sampling relies on the unassisted molecular diffusion of gaseous agents (analytes) through a diffusive surface onto an adsorbent. Unlike active sampling, passive samplers require no electricity (pumps), have no moving parts, are simple to use and offer results comparable to active samplers but without the added cost.

Whole Air Sampling
A whole air sample is collected when the air is drawn into some sort of containment vessel such as a Tedlar® bag or “Summa” canister. The method of collection is easy and the compounds of interest are recovered directly from the vessel. Recovery is a function of several factors which include, the surface area of the vessel, the chemistry and vapor pressure of the contaminants, the influence of various matrix effects, and the ability to begin with a vessel free of contamination. Supelco offers Tedlar® Gas Sampling Bags and Bulbs to meet your whole air sampling needs.