Mercury SPOT Kit Field Trial at Oak Ridge National Laboratory
Correlation of EPA Method 7471
with the Mercury SPOT Kit
Summary of Results
|
|
METHOD |
Mercury |
SPOT |
Kit |
|
SAMPLE |
7471 |
1 ppm |
4 ppm |
400 ppm |
|
ID |
(ppm) |
RESULT |
RESULT |
RESULT |
|
127 |
2850 |
POS. |
|
POS. |
|
324 |
2060 |
INVALID |
POS. |
POS. |
|
223 |
2020 |
POS. |
|
POS. |
|
524 |
1830 |
INVALID |
POS. |
POS. |
|
621 |
1360 |
INVALID |
POS. |
POS. |
|
424 |
1190 |
INVALID |
POS. |
POS. |
|
5102 |
1100 |
POS. |
|
POS. |
|
729 |
804 |
INVALID |
POS. |
|
|
920 |
589 |
POS. |
|
POS. |
|
810 |
454 |
POS. |
|
POS. |
|
8102 |
400 |
POS. |
|
|
|
025 |
376 |
INVALID |
POS. |
POS. |
|
5201 |
360 |
POS. |
|
POS. |
|
7601 |
310 |
POS. |
|
|
|
211 |
281 |
POS. |
|
NEG. |
|
115 |
258 |
INVALID |
POS. |
NEG. |
|
7509 |
250 |
POS. |
|
|
|
5107 |
240 |
POS. |
|
|
|
9402 |
240 |
POS. |
|
|
|
312 |
226 |
POS. |
|
NEG. |
|
717 |
183 |
POS. |
|
NEG. |
|
5105 |
160 |
POS. |
|
NEG. |
|
7905 |
160 |
POS. |
|
|
|
7209 |
150 |
POS. |
|
|
|
9308 |
150 |
POS. |
|
|
|
4607 |
140 |
POS. |
|
NEG. |
|
7801 |
120 |
POS. |
|
|
|
9502 |
110 |
POS. |
|
|
|
4604 |
100 |
POS. |
|
NEG. |
|
8301 |
100 |
POS. |
|
|
|
4107 |
73 |
POS. |
|
|
|
512 |
64.8 |
POS. |
|
NEG. |
|
7107 |
57 |
POS. |
|
|
|
918 |
56.2 |
POS. |
|
NEG. |
|
4203 |
38 |
POS. |
|
NEG. |
|
5106 |
36 |
POS. |
|
|
|
013 |
29 |
POS. |
|
NEG. |
|
822 |
21.4 |
POS. |
|
NEG. |
|
8408 |
21 |
POS. |
|
|
|
8001 |
19 |
POS. |
|
|
|
8808 |
18 |
POS. |
|
|
|
4101 |
17 |
NEG. |
|
|
|
7704 |
15 |
POS. |
|
|
|
8205 |
9.2 |
POS. |
|
|
|
8906 |
3 |
POS. |
|
|
|
9506 |
1 |
NEG. |
|
|
|
8705 |
0.4 |
NEG. |
|
|
Description
A total of 47 soil samples were tested using the Mercury SPOT Kit. The
samples came from the East Fork Poplar Creek floodplain in Oak Ridge,
Tennessee. The samples were dried, pulverized, and the contamination of
mercury determined by Cold Vapor Atomic Absorption Spectrometry (CVAAS).
The samples contained mercury between 0.4 and 3000 ppm (mg/kg). The
predominant forms of mercury in these samples were elemental mercury and
mercury sulfide.
1 ppm Detection Level Results
* All 47 samples were tested using the Mercury SPOT Kit at the 1 ppm
detection level.
* Thirty seven of the 45 samples containing mercury at concentrations
greater than 1 ppm gave a positive result.
* Seven of the highly contaminated samples caused the Mercury SPOT pad
to become clogged resulting in slow flow rates of the sample, wash, and
substrate solutions. The signal generated in these tests had a high
background signal (the entire surface of the Mercury SPOT pad turned dark
blue) which prevented an interpretation of the test result.
* Two samples contained 1 ppm mercury or less and gave negative
responses in the SPOT test.
* One of the soils contained 17 ppm mercury and gave a false negative
result. This soil was found to contain an interferant which prevented the
detection of mercury by the Mercury SPOT Kit.
4 ppm Detection Level Results
Note: By placing only one drop of extract into the enzyme
reagent tube instead of four, the test detection level becomes 4 ppm.
When the seven extracts giving invalid results were retested at the 4 ppm
detection level, the flow rates of solutions through the Mercury SPOT pad
was normal and positive results were observed.
400 ppm Detection Level Results
In order to demonstrate the utility of the Mercury SPOT Kit in monitoring
mercury contamination at levels greater than 1 ppm, twenty three extracts
were diluted 1:400 into deionized water (making the detection level 400 ppm)
and tested.
* The eleven samples containing 360 ppm mercury or greater gave
positive results.
* The twelve samples containing 281 ppm mercury or less gave negative
results.
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