Simple Field Screening Method for
White Phosphorus (P4) In Sediment
MARIANNE E. WALSH, CHARLES H. RACINE, CHARLES M. COLLINS,
CARL BOUWKAMP AND PHILIP G. THORNE
meter-size particles of white phosphorus. The
INTRODUCTION
method was designed so that many samples could
Analytical methods have been developed for
be tested for white phosphorus in the field with-
white phosphorus (WP, P4) residues in sediment
out the use of organic solvents or sophisticated
and water (Walsh and Taylor 1993 and Walsh
equipment. In addition, a screening procedure
1995). These methods require that a field sample
based on solid phase micro-extraction (SPME)
be brought to a laboratory where a subsample is
(Zhang and Pawliszyn 1993) was tested. This
extracted with solvent and the extract analyzed
SPME procedure, however, requires the use of a
by gas chromatography. The cost of this analysis
field-portable gas chromatograph.
is approximately 0 per sample. These meth-
ods have been used to analyze several thousand
samples from Eagle River Flats (ERF), the impact
METHODS
area on Fort Richardson, Alaska (Racine et al.
1992, 1993) and from 24 other Army sites (Sim-
Materials
mers et al. 1994).
White phosphorus (P4) and isooctane were ob-
WP contamination coincides with areas of nu-
tained from Aldrich Chemical Company.
merous impact craters with standing water (Ra-
In the laboratory, white phosphorus particles
cine et al. 1993). Within these areas, high concen-
with diameters ranging from 0.3 to 1.8 mm were
trations of WP are distributed in areas less than a
produced under water from molten white phos-
meter in diameter, which presumably correspond
phorus using a Gilson Microman Positive Dis-
to the point of impact of a WP projectile. Imme-
placement Pipet (size M25) equipped with dispos-
diately surrounding the impact points are large
able capillaries and pistons. The diameter of each
areas where WP is at very low concentration
particle was measured using a SPI (Swiss Preci-
(<0.001 g/g) (Walsh and Collins 1993). Samples
sion Instruments) 6-in. caliper with 0.1-mm gra-
with high concentrations were found to contain
dations.
Solid phase micro-extraction fiber (100-m
WP particles ranging in size from less than 0.1 to
5 mm (Racine et al. 1993, Walsh and Collins 1993).
polydimethylsiloxane) assemblies were obtained
Since Army training areas tend to be large (sever-
from Supelco.
al square kilometers) and WP tends to be hetero-
geneously distributed in discrete and relatively
Collection of
small (less than 1-m2) areas, the number of sam-
sediment samples
Sediment samples were collected from Eagle
ples required to screen an area for contamination
River Flats, Ft. Richardson, Alaska, a site contam-
can be unrealistically large. Depending on the
inated from white phosphorus munitions (Racine
objectives of a sampling effort, the costs and time
et al. 1992, 1993). Sediment samples were collect-
required for laboratory analyses may be unac-
ed by two methods. For the first method, a sam-
ceptable.
ple site was chosen, and then several small sam-
The objective of this work was to develop a
ples of the surface sediment within a 0.5-m radius
quick and easy, low cost method to detect milli-
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