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5.
Repeat steps 3 and 4 one more time.
6.
Add 25mL of methanol to the reservoir. Apply a
light vacuum (~5in. Hg) and pull approximately
1mL through the disk. Vent the vacuum and allow
the disk to soak for 1 minute.
7.
Apply vacuum and pull methanol through the disk
until the methanol surface is 1–2mm above the
surface of the disk or prefilter.
8.
Add 10mL of reagent-grade water to the reservoir.
Apply a light vacuum and pull the water through
the disk until the surface is covered with about
1–2mm of water.
9.
Repeat steps 7 and 8 one more time.
Note:
It is important that the disk is not allowed to
dry out before introducing the sample. Drying of
the disk at this point could lead to decreased
yields.
SampleExtraction:
1.
Pour or decant the sample into the reservoir and apply
vacuum. Decant and extract as much liquid as possible
before adding sediment to the reservoir. Do not let the
disk dry before adding sediment.
Note:
Use an appropriate vacuum to keep the extraction
time to more than 10 minutes, as faster extraction times
will reduce recoveries.
2.
After sample extraction is complete, remove as much
residual water as possible from the disk by applying
vacuum to dry the disk for 10 minutes.
SampleDrying:
1.
Use acetone (5–6mL) to remove any remaining water
from the disk.
2.
Leaving an open vacuum, add 5mL acetone around the
lower portion of the reservoir and to the top of the disk.
Apply maximum vacuum to dry the disk for 5 minutes.
Note:
Do not allow acetone to sit in the reservoir.
3.
If 5mL does not remove all remaining water, try an
additional 1mL, but do not exceed a total of 6mL.
Note:
Acetone may reduce yields if used in large
quantities or for long durations.
SampleElution:
1.
Put receiving vessel in place. Elute twice with 25mL of
n
-hexane. Smaller volumes of solvent may be used if the
elution techniques have been validated. When adding
elution solvent, rinse down the sides, washing the walls
of the reservoir in the process.
2.
Carefully apply vacuum to pull a few drops of
n
-hexane
through the disk, and then release the vacuum. Allow
the
n
-hexane to soak the disk for two minutes before
applying full vacuum to remove residual
n
-hexane and
dry the disk.
3.
Repeat the process in steps 1 and 2 with a second
aliquot of eluting solvent.
*
Optional Step: It may be desirable to further dry and
filter the combined hexane eluates before transferring
them to a pre–weighed vaporation dish. Pass the hexane
through a small or large sodium sulfate-containing Dry
Prep tube (cat.# 26075 or 26076), and a 0.45µm PTFE
syringe tip filter (cat.# 26073), connected to the outlet of
the Dry Prep tube.
4.
Transfer eluted hexane sample to the pre-weighed
evaporating dish. Rinse collection vessel with two
additional 5mL aliquots of n-hexane, add rinse to
evaporating dish.
5.
Evaporate the
n
-hexane, at a temperature of 30–40°C,
from the pre-weighed dish until a constant weight is
reached.
End Note:
When using glass filter beads instead of the
prefilter, modifications to the procedure are required. Due to
the difference in physical properties, it is necessary to
reduce all quantities of the solvents used to 10mL instead of
25mL during the disk conditioning and sample elution. In
the sample drying process, start with 4–5mL of acetone. If
any water remains in the sample, try using up to 6mL.
Product Listing:
Description
cat. #
Oil &Grease SPEDisk, 47mm (20pk.)
26022
Flow Filter, 47mm (20pk.)
26024
Resprep
™
Maxi-Manifold, Complete Station 26026
Resprep
™
Maxi-Manifold, 1-Station
26025
Individual Maxi-Manifold Station
26027
Replacement Reservoir, 1L
26028
Dry Prep I
Sodium sulfate drying tube - small (50pk.)
26075
Dry Prep II
Sodium sulfate drying tube - large (50pk.)
26076
25mm Syringe Tip Filter, PTFE, 0.45µm 26073
US EPAMethod 1664 Oil &Grease ReferenceMix
Each
5-pk.
10-pk.
31457
31457-510
w/data pack 31457-500 31457-520 31557
RestekTrademarks:
Resprep
OtherTrademarks:
Freon (E.I.duPontdeNemours&Co., Inc.)
