the pesticide solution and given a decontamina-
were determined following the procedure outline
tion treatment (Table 3). Following decontamina-
in the Federal Register (1984).
tion, the two test pieces were placed in a 40-mL
Primary certified standards were purchased
from Ultra Scientific (100 g/mL in hexane) and
clean borosilicate glass vial containing 30 mL of
each was diluted to 10 g/mL with pesticide-
DI water, capped, and allowed to desorb for a
specified time (Table 3). The test pieces were then
grade hexane. A combined standard was made by
removed from the water and the DI water was
adding a volume of each of the diluted pesticide
solvent extracted so that it could be analyzed for
standards into a volumetric flask containing hex-
ane (1 g/mL). Working standards were made
pesticides. Vials with the test solution but no cas-
ing served as sorption controls. To show that
each sampling day by serial dilution of the com-
these materials did not leach pesticides or con-
bined standard into hexane (600, 400, 200, 100, 20,
taminants that interfered with these analyses, one
and 4 ng/mL). All standards were kept in the
set of well casing materials was placed in DI wa-
dark in the freezer.
ter for 24 hours and then the water was solvent
extracted and analyzed (i.e., blanks or desorption
First pesticide study--No treatment
controls).
The purpose of this study was to determine
Extraction of pesticides from the 30 mL of aque-
what concentrations of pesticides would be car-
ous solution followed a modified EPA method
ried over if the test pieces received no treatment
#505 pr ocedure (US EPA 1991) as follows: nine
at all (Table 3).
grams of reagent sodium chloride was added to
each vial, which was then shaken to dissolve the
Second pesticide study--Effect of rinsing
salt; 3 mL of pesticide-grade hexane was added,
The purpose of this study was to eliminate any
and the vial was recapped and shaken hori-
carryover of pesticides that might be contained in
zontally for three hours on a shaking table. The
the droplets of test solution that clung to the test
vials were allowed to stand vertically for approx-
pieces. This was done by briefly rinsing the test
imately 10 minutes to allow separation of the two
pieces with DI water (Table 3).
phases. The hexane layer was drawn off with a
Pasteur pipet and placed in a 1.8-mL amber au-
Third pesticide study--Effect of a hot
tosampler vial. The autosampler vials were
detergent wash and rinse
stored in the refrigerator (4C) until analyzed.
The purpose of this study was to see how effec-
Analyses were run on a Hewlett-Packard (HP)
tive a hot detergent water wash and hot DI water
5890 series II gas chromatograph (GC) using an
rinse would be for removing pesticides (Table 3).
electron capture detector and equipped with an
HP 6890 series autosampler injector, all under the
Fourth pesticide study--Effect of a hot
control of HP-Chemstation software. The operat-
detergent wash on other polymers
The purpose of this study was to determine if a
ing parameters are given in Table 4. The MDLs
hot detergent wash and DI rinse would also be
effective for removing pesticides from three poly-
Table 4. Operating parameters for GC analyses of
pesticides.
meric tubing materials (tubings): polyvinylidene
fluoride (PVDF), low-density polyethylene (LDPE),
Mode: Splitless
and a copolymer of vinylidene fluoride and
Column: J & W Scientific DB-5.625,
30-m 0.255-mm i.d., 0.50-m film.
hexafluoropropylene [P(VDF-HFP)].
Injector temperature: 250C
The procedure was the same as the previous
Detector temperature: 300C
experiment except that four pieces of the tubing
Purge time: 1.0 min
were placed in each of the glass vials containing
Oven parameters:
30 mL of the pesticide solution (Table 3). The tub-
Initial temperature: 150C
ing surface area/solution volume ratio was 1.33
Initial hold time: 2 min
Ramp rate and final oven temperature: 10/min to 250C
cm2/mL. Desorption controls (blanks) consisted
Final hold time: 8 min
of vials that contained 30 mL of deionized water
Carrier gas: nitrogen
and four test pieces.
Makeup gas: nitrogen
Column flow rate: 1.0 mL/min
Fifth pesticide study--Effect of various
Purge rate: 2.5 mL/min
Makeup gas flow rate: 60 mL/min
decontamination treatments on LDPE
Injection volume: 1 L
The purpose of this study was to determine
8
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