8
SPME Holder
6
4
SPME Phase
Headspace
2
y = 0.80875 + 3.9172x
40 g Sediment
r2 = 0.90301
Plus Water
Figure 7. Solid phase micro-extrac-
0
0.5
1.0
1.5
2.0
WP, Particle Diameter (mm)
tion (SPME) of a sediment sample
to test for the presence of white phosphorus. Follow-
Figure 6. Diameters of orange residue left by WP
ing exposure to the headspace above the sample, the
particles of known diameter after placement in a
SPME phase is transferred directly to the injection
smear of mud on an aluminum pie plate and heating
port of the gas chromatograph.
until water evaporates.
The orange residue produced from WP is acid-
tained. Following analysis by headspace SPME, a
ic and rich in orthophosphate. However, the sed-
10-mL aliquot of isooctane was added to each
iment at ERF is highly buffered and is also rich in
sample jar, and the samples shaken for 18 hours.
A 1-L aliquot of the isooctane extract was inject-
orthophosphate. Therefore efforts were unsuc-
cessful to confirm a positive field test measuring
ed into the gas chromatograph. The mass of white
pH or orthophosphate.
phosphorus detected per injection by each meth-
od was calculated based on external calibration
standards. The mass found in the 1 L of isooc-
SPME and future work
The field screening approach described in this
tane was also used to calculate the concentration
in g/g (Table 3). For the three samples where
report is simple, quick and unsophisticated. Posi-
tive results were obtained for samples where the
the white phosphorus concentration was greater
than 0.5 g/g, two additional 40-g subsamples
laboratory method indicated WP concentrations
above 1 g/g. We next tested a SPME procedure
were spread across the bottom of an aluminum
(Fig. 7) to allow detection of lower concentrations
pie plate and heated.
of WP without solvent extraction. This procedure
The amount of WP detected in the headspace
does require the use of a gas chromatograph; there-
of each sample by SPME correlated well with that
fore, field personnel would need to be trained in
found by solvent extraction. Of the 19 samples
GC setup and maintenance. A series of discrete
tested, 13 were negative by both methods. For the
sediment samples were collected from Eagle
six positive samples, the amount of WP detected
River Flats. For each sample, a 40-g wet subsam-
by SPME was proportional to that found by sol-
ple and 10 mL of reagent grade water were placed
vent extraction, i.e., the highest masses of WP
in a 120-mL jar equipped with a septum cap. The
detected were for those samples with the highest
jars were sealed and manually shaken 10 times so
concentration. Both methods were comparable in
that the sample was well mixed and coated the
detection capability. The certified reporting limit
sides of the jar. Samples stood at room tempera-
(CRL) of the solvent extraction procedure is
ture (20C) for one hour, and then each sample
0.00088 g/g. The lowest concentration detected
was analyzed as follows. The jar was shaken an
in the positive samples was slightly greater than
the CRL (0.00094 g/g), and SPME also gave a
additional 10 times, and the SPME fiber was ex-
posed to the headspace for 5 min. Immediately
positive result for this sample. Future work on
following exposure to the headspace, the SPME
the SPME procedure will be to attempt to cali-
fiber was inserted into the injection port of the
brate for quantitative results.
gas chromatograph, and a chromatogram ob-
For those samples that were subjected to the
6
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