Environmental Sampling Techniques - Fundamentals of Environmental Sampling and Analysis - page 82

(a) (b)

Filter

Acceleration jet
Inlet cover

Flow
collection
shim

Inlet
Vent'tube
Fraction zone
Bug screen

Air in

Air
pump

Air
flow

Filter

Pressure tab
VFC

Hl-Vol blower

Air out

Figure 4.8 Common sampling equipments used for air. (a) Total suspended particulate matter (TSP)
sampling system (Girard, JE, principles of Environmental Chemistry, 2005, Jones and Bartlett
publishers, sudbury, MA. WWW. jbpub. com. Reprinted with permission.), and (b) PM-10 sampling
system (Norwegian Institute for Air Research, 2001)

5-10 cfm. This system is excellent for measuring low concentrations of SVOCs,
PCBs, pesticides, or chlorinated dioxins in ambient air. The personal sampling
pumps are portable sampling devices that draw air through a number of sampling
media including adsorbent tubes, impingers, and filters (discussed below).
Air sampling collection media and device shown in Figure 4.9, in principle, can
be divided into four major categories: (1) by the collection of an air sample in a
container such as a canister or Tedlar bag, (2) by filtration of air using filter cassette,
(3) by chemical reaction or absorption through the bubbling of air in a liquid
medium in an impinger, and (4) by adsorption of chemicals in the air on the
adsorbing materials. The SUMMA canister (6 or 15 liters) uses the SUMMA electro-
polishing process to form chromium and nickel oxides on the internal surface so that
adsorption of VOCs is minimized. Air samples are collected by allowing air to bleed
into or be pumped into the canister. SUMMA canisters are used to measure low to
ultra low concentration of gaseous compounds, typically in the ppt-ppb range. The
Tedlar bag, albeit with the same principle, are simple and effective means for
contaminants of high concentrations ( 10 ppm v ). An impinger is used to collect

compounds in condensable concentrations or those that can be readily retained by
absorption or reactions with the liquid in the impinger. Sorbent tubes are used
primarily in industrial hygiene. There are two types of sorbing materials - the
thermally desorbed media including Tenax and carbonized polymer and the solvent-
extracted media such as XAD-2 polymer, activated carbon, and Tenax. Air sampler
using PUF is a combination of filter (glass or quartz) and a polyurethane foam to

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