Hach DR/700 Procedures Manual page 312

POLYACRYLIC ACID,
5 minutes
7.
Immediately
place the cylinders in
the dark. Begin
timing a 5-minute
period.
continued
8.
After the 5-
minute period, fill a
10-mL cell to the
10-mL line with the
blank. Cap and label
the cell "reagent
blank".
Fill a 10-mL cell to
the 10-mL line with
the prepared sample.
Cap and label the cell
"sample".
50-62
9.
Place the cell
labeled "reagent
blank" in the cell
holder.
Note: In bright sunlight,
it may be necessary to
close the cell
compartment cover.