61-68
OXYGEN DEMAND, CHEMICAL, continued
4. Hold the vial at a
45-degree angle.
Pipet 2.00 mL
(0.2 mL for 0 to
15,000 range) of
sample into the vial.
Note: To ensure a
uniform sample aliquot,
stir sample with
magnetic stirrer while
drawing sample aliquot
into the pipet.
Note: For greater
accuracy, three
replicates should be
analyzed and the results
averaged. This is
especially important for
the High Range Plus test.
Note: Spilled reagent
will affect test accuracy
and is hazardous to skin
and other materials. Do
not run tests with vials
which have been spilled.
If some spills, wash with
running water.
Note: For proof of
accuracy, use COD
standard solutions
(preparation given in
the Accuracy Check) in
place of the sample.
5. Replace the vial
cap tightly. Rinse the
COD vial with
demineralized water
and wipe the vial
clean with a paper
towel.
Note: When using High
Range Plus COD vials,
tighten the vial cap with
the COD cap tool
provided.
6. Hold the vial by
the cap and over a
sink. Invert several
times to mix the
contents. Place the
vial in the preheated
COD Reactor.
Note: The vial will
become hot during
mixing.
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