Hach DR/700 Procedures Manual page 302

PLATINUM,
4.
Add the contents
of one Chromium 1
Reagent Powder
Pillow to each bottle.
Swirl to dissolve.
Place a hollow
polyethylene stopper
loosely in to each
bottle.
7.
Add the contents
of one Sodium
Metabisulfite
Reagent Powder
Pillow to each bottle.
Swirl to dissolve.
continued
5.
Place both bottles
in a boiling water
bath for five minutes.
Note: The sample may
become turbid upon
heating. The turbidity
will clear when
hydrochloric acid is
added in Step 8.
8.
Using a 10-mL
Mohr pipet bulb,
carefully add 10 mL
of concentrated
hydrochloric acid to
each bottle. Swirl to
mix. The bottles will
become warm to the
touch.
50-52
6.
Cool both bottles
under tap water to
about room
temperature.
9.
Using the 1-mL
calibrated dropper,
add 1.0 mL of N,N'-
Dimethyldithioox-
amide Indicator
Solution to each
bottle. Swirl to mix.