Hach DR/700 Procedures Manual page 564

COBALT,
continued
4.
Measure 25 mL of
sample in a 25-mL
graduated mixing
cylinder (the prepared
sample).
Note: If sample is less
o o
than 10 C (50 F),
warm to room
temperature prior to
analysis.
Note: For proof of
accuracy, use a 1.0 mg/L
cobalt standard solution
(preparation given in
Accuracy Check) in
place of the sample.
7.
Add 1.0 mL of
0.3% PAN Indicator
Solution to each
cylinder. Stopper and
invert several times to
mix.
Note: Use plastic
dropper provide to add
PAN solution.
5.
Measure 25 mL of
demineralized water
in a second 25-mL
cylinder (the blank).
3 minutes
8.
Wait 3 minutes.
Note: During color
development, the
sample solution color
may vary from green to
dark red, depending on
the chemical make-up of
the sample. The
demineralized water
blank should be yellow.
61-8
6.
Add the contents
of one Phthalate-
Phosphate Reagent
Powder Pillow to
each cylinder.
Stopper and
immediately shake to
dissolve.
Note: If sample contains
3+
iron (Fe ), it is
important that all of the
powder be dissolved
completely before
continuing with Step 7.
9.
Add the contents
of one EDTA Reagent
Powder Pillow to
each cylinder.
Stopper and shake to
dissolve.