Table 5. Recommended solvent rinses for soluble contaminants (from
U.S. EPA 1991).
Solvent
Soluble contaminants
Water
short-chain hydrocarbons
inorganic compounds
salts
some organic acids
some polar organic compounds
Dilute acids
basic (caustic) compounds
amines
hydrazines
Dilute bases (detergent, soap)
metals
acidic compounds
phenols
thiols
some nitro and sulfonic compounds
Organic solvents, e.g., alcohols,
nonpolar organic compounds
ethers, ketones, aromatics,
straight-chain alkanes (e.g.,
hexane), common petroleum
products (e.g., fuel oil, kerosene)
thoroughly with potable water, 3) rinse with deion-
instead of a dilute nitric acid rinse when cleaning
ized or distilled water, and 4) air dry. For grossly
stainless steel. They stated that this was because
contaminated equipment they recommended the
nitric acid may oxidize steel. However, any acid
following protocol: 1) wash with detergent solu-
solution can corrode a stainless steel surface
tions and rinse with potable water, 2) rinse with
(Driscoll 1986). For glass and polymeric surfaces,
an organic solvent (preferably isopropanol), 3)
the purpose of an acid rinse is to remove sorbed
wash with a detergent solution a second time and
metal ions from the surface. This procedure
rinse with potable water, 4) rinse with deionized
would be of questionable effectiveness for any
or distilled water, and 5) air dry. They cautioned
metal surface.
that this equipment should not be used to sample
Region IV of the U.S. EPA (U.S. EPA Region IV
water suspected of being contaminated at low or
1991) recommended different protocols for clean-
trace levels. However, they did not supply any
ing equipment used to collect samples for trace
data to back up either of these recommended
organic compounds and metals, depending upon
methods.
the material being cleaned. For fluoropolymers
The U.S. EPA (1991) gives different recommend-
(Teflon) and glass they recommended an acid
ed solvent rinses for various contaminants (Table
rinse, but for stainless steel and other metal sam-
5). However, the list of recommended organic sol-
pling devices they did not. They did not explain
vents for removing nonpolar organic contami-
why these methods differed. They also gave dif-
nants is general, and it is doubtful whether a num-
ferent protocols for precleaning various types of
ber of the solvents they recommend should be
sampling tubings. They recommended that stain-
used. For example, fuel oil or kerosene can both
less steel tubing receive a detergent wash and rinse
be target analytes.
with high-quality water and a rinse with (an un-
When sampling for organics, draft guidance by
specified) organic solvent. Silastic rubber tubing
the U.S. EPA for RCRA sites (U.S. EPA 1992) rec-
would receive a similar wash but would not be
ommends two solvent rinses: one with hexane or
rinsed with organic solvent. In this case, the rea-
methanol, followed by a rinse with acetone, fol-
son is probably because the rubber tubing would
lowed by a rinse with organic-free reagent water.
be degraded by most organic solvents. The glass
When sampling for metals, this document also rec-
and Teflon tubings receive only an organic sol-
ommended using a dilute hydrochloric acid rinse
vent rinse, followed by air drying for the glass
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