chart (i.e., GRO, DRO, or RRO, for a soil or water
threne, asphaltines, etc.). Carbon tetrachloride also
matrix), about 4 minutes after the catalyst had been
serves as a solvent to quantitatively remove the hydro-
added to the solvent extract. The technology developer
carbons from soil and water sample matrices. The team
prepared these color charts using commercial petroleum
that prepared and analyzed the field samples for this
technology demonstration was made up of John Hanby,
products that represented the different hydrocarbon
the developer of the Hanby Test Kits and three meth-
ranges (i.e., GRO, DRO, etc.) and taking them through
ods of measurement, and one of his employees. Hence-
the various preparation steps for either a soil or water
forth, this team will be called the "technology devel-
sample. However, because each sample was also to be
oper." The following steps were used to prepare soil
analyzed by the HM 2010 and 2000, a correction factor
and water samples for sequential analysis by the visual
was necessary for the visual determinations because
and spectrophotometric methods.
both of the spectrophotometric methods specify that
For soils contaminated with GRO compounds, 5.0
only 0.5 g of the catalyst be used to produce the color.
0.2 g was transferred to a VOA vial containing 10
This is half the amount that was used when the visual
mL of an extraction solvent composed of 20% carbon
color charts were produced. To correct for the decreased
tetrachloride/80% n-heptane (v/v). For the DRO and
volume of catalyst, which remains as a separate phase,
RRO contamination, 5.0 0.2 g of soil was first trans-
the concentrations indicated by the photo charts were
ferred to an empty VOA vial and then the extraction
divided by two after the sample's color intensity was
solvent was added. The sample vial was agitated until
matched to the chart.
the sample was completely dispersed. In the case of a
The HM 2010 and HM 2000 are both in the early
clay that would not disperse by manual shaking, the
stages of development, and this field exercise was a
cap of the VOA vial was removed and a clean
beta test. For spectral analysis, the developer claims
metal spatula was used to break apart the soil matrix,
that the HM 2010 transmits (by reflectance) a single
exposing as much surface area as possible. Extraction
wavelength of energy through the 1- to 2-cm layer of
was performed over a 4- to 5-minute period, then the
catalyst, and that the amount of transmitted energy is
sample was allowed to sit until 4.2 mL of a clear sol-
inversely proportional to the concentration of TPH
vent layer could be decanted into a specially designed
present in the sample. In its current design, the light
optical cuvette (a mark on the wall of the vessel
source is located above the cuvette and the detector is
denoted the 4.2-mL volume that was required). Then,
centered beneath the cuvette. For the light energy to
0.5 g of AlCl3 (a strong Lewis acid catalyst) was added
pass through the sample, the cap of the cuvette must be
to the cuvette containing the sample extract. The
removed before it is placed in the optical cell. The HM
cuvette was capped and shaken repeatedly for periods
2000 measures reflectance in the visible region (400
of 15 seconds, over a 2- to 3-minute span, to fully
750 nm) of the energy spectrum, using a charged-couple
develop the color resulting from the Friedel-Crafts alky-
device (CCD) array detector. In a way that is similar to
lation reaction.
the single wavelength system, the developer claims that
For water samples, a separatory funnel was filled to
the amount of reflectance is inversely proportional to
a 500-mL mark, and 5 mL of carbon tetrachloride was
the TPH concentration. A tungsten-halogen continuum
added. The capped separatory funnel was then agitated
light is focused on the catalyst and the energy that is
to completely intersperse this immiscible solvent
not absorbed by the sample is reflected back to the
throughout the aqueous sample, while any pressure
detector for measurement. Both the light source and
buildup was periodically vented. This extraction step
detector are located beneath the cuvette in this spectro-
took 2 to 3 minutes, after which the denser solvent was
photometer. As the detector is capable of measuring an
allowed to settled to the bottom of the funnel. While
energy spectrum, the developer may include, in the
the carbon tetrachloride was separating, the drain tube
future, a qualitative analysis of the unique spectrums
of the separatory funnel was dried with a clean, rolled-
of chromophoric (color-producing) Friedel-Crafts
up piece of paper towel, then the clear solvent layer
reaction products that are created for different petro-
was drained into a cuvette, filling it to the 4.2-mL mark.
leum fuels, oils, and solvents.
After the cuvette was checked for water droplets cling-
Currently, both spectrophotometric instruments are
ing to the walls (if they were present, the solvent was
only capable of reporting TPH values relative to cali-
transferred to a second optical tube), 0.5 g of AlCl3
bration curves that are developed in the same fashion
was added, the tube was capped, and then it was shaken
as for the visual method of analysis. Therefore, the cali-
repeatedly for periods of 15 seconds, over a 2- to 3-
bration models consisted of instrumental responses to
minute span, to fully develop the color.
standards prepared from commercial petroleum prod-
The TPH concentration was visually interpreted by
ucts using either soil or water sample matrix procedures.
comparing the intensity of color to the appropriate color
These calibration models can currently be stored as an
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