IAAI, Washington State Chapter
9116 E Sprague Ave. #186
Spokane, WA 99206-2301
RESEARCH & PROTOCOL
Absorbent collection of ignitable liquid residue from
Prepared by Noel Putaansuu and Dale Mann of MDE
Keep in mind that the surfaces to be sampled can not have
any standing water on them (wet surfaces are problematic to powder saturation).
Allow any standing water to dissipate/evaporate naturally to dryness prior
to applying the absorbent. Do not heat the concrete to dry it. 60 minutes
is sufficient time to allow the absorption to take place. Sweep the powder
up with a new disposable brush and place in an appropriately sized can for
laboratory analysis. Take the time to vigorously sweep up the fines as they
have had the most intimate contact with the surface of interest.
A comparison sample should be prepared as well. Select an
area well separated from the area of interest and repeat the sampling process.
Remember it is imperative to also send a control sample of the absorbent to
the laboratory for comparison purposes.Unscented clay cat litter was found
to be a readily available, inexpensive and an effective absorptive media.
The cat litter can be lightly ground to reduce the particle size. (Finer particles
increase the exposed surface and are more effective in the absorption process
on concrete.) Prepare the cat litter by heating several pounds at 121°C
(250°F) overnight in a shallow dish. After cooling, package quantities
in one-quart cans (or other vapor-tight container) for future use. This is
a convenient quantity and generally will provide sufficient material for a
single fire scene.
Pre-conditioned cat litter (unscented)
Clean cans to contain samples
New paint brushes (one for each sample)
Disposable scoops (stiff paper is adequate)
Clean plastic tenting material to protect the site during the waiting period (optional)
Clean and dry the area to be sampled
Photograph/document the sample area
Spread the absorbent powder over the area to be sampled
Record the time that the absorbent is applied
Photograph/document the sample area and absorbent
Wait a minimum of 60 minutes
Sweep up the sample on to the collection tray (clean brush and tray)
Record the time
Deposit into the can, seal and label.
Dispose of the brush and tray
Samples going to the lab
Subject area (area of origin)
Comparison area (representative of site but outside the area of origin)
Control sample of absorbent powder (clean/unused)