Table 4. Methods of analysis used by the reference laboratory.
TPH
Sample
EPA SW-846
Quantitation
Approx. boiling
fraction
location
method
range
point range
BTEX*
GRO plume
8020
NA
NA
60 to 170C
GRO
GRO plume
8015B
C6 to C12
160 to 540C
DRO/RRO
DRO/bunker C
8015B**
C10 to C40
plume and plots
*Benzene, toluene, ethyl-benzene, and the xylenes.
**Methylene chloride extraction.
minative method used by the QA laboratory was simi-
QA laboratory for the samples contaminated with GRO.
lar to that used by the reference laboratory, i.e., Meth-
Instead, this laboratory only reported concentrations for
ods 8020 and 8015 (U.S EPA 1986).
the benzene, toluene, ethyl-benzene, and the xylenes
(BTEX). The reference laboratory and CRREL also
reported the total BTEX concentration in all the samples
RESULTS
contaminated with GRO compounds. The BTEX val-
ues determined by these three laboratories are shown
Table 5 gives the TPH results for this technology
in Table 6.
demonstration. The results presented for the technol-
Lastly, the values reported in these tables for the
ogy developer only include the values reported for the
soil samples are based on moist weight and all values
visual and HM 2000 measurement methods because the
were rounded to two significant figures, or less. A single
HM 2010 system is not ready for evaluation. Prior to
significant figure value was reported when it was lim-
recording the reference laboratory results given in Table
ited by the instrument display on the HM 2000 or by
5a, the data had to be manipulated to change the units
the concentration provided with the visual comparison
and to address the presence of surrogate compounds.
chart. For completeness, the percent dry weights deter-
This alteration was necessary for the methanol extracts,
mined for the all of the soil samples and the background
because the reference laboratory had not been informed
soil used for the matrix spike samples are presented in
of the volume of extraction solvent used, and that two
Table 7.
surrogate compounds were present. As a result, they
A close inspection of the values for the water
initially reported TPH values on a mg/L basis and had
samples contaminated with GRO compounds shows
concentrations (low) for the matrix blank and trip blanks
that these samples may not have had stable analyte con-
that were in reality the surrogate compounds. All of the
centrations. These samples were handled following the
values were changed to mass per mass basis by multi-
procedure recommended by the State of California;
plying the reported value by the volume of methanol
therefore, they were not preserved by acidification. The
divided by the weight of the soil sample (a default value
holding times for the majority of these samples, with
of 5.0 g was used for all QA samples). To address the
the exception of WG-11, -10, -12, and -13, which were
surrogate contribution to the TPH values reported, an
analyzed after 6 days, was 9 to 14 days, or longer.
average concentration based on the two trip blanks and
Moreover, three water samples that were apparently
soil matrix blank was subtracted from samples that were
misplaced by the reference laboratory were held for 29
prepared and analyzed with the same dilution factor.
days prior to analysis (Table 5b), while those analyzed
This latter correction affected only two samples. All of
by the QA laboratory were held for about 40 days (Table
the other samples were diluted further by at least a fac-
6). As a results, all of the matrix spike recoveries were
tor of 10, thereby making this correction unnecessary.
lower than expected and, in general, there is a trend
Failure to inform the reference laboratory of the sample
showing that the samples held for longer periods had
preparation procedure was an oversight by the technol-
lower determined analyte concentrations. So, all of the
ogy demonstration program.
groundwater samples, with the exception of the PE
Another problem, which resulted from inadequate
samples, may have lost analytes from biodegradation
communication, was that some of the samples sent to
during refrigerated storage. The PE samples were not
the QA laboratory were not analyzed for the appropri-
affected by this loss mechanism because HPLC grade
ate parameters. No TPH values were reported by the
water is abiotic.
8
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