Hach DR/700 Procedures Manual page 546

SILVER,
continued
4.
Add the contents
of one Silver 1
Powder Pillow to a
dry 50-mL mixing
graduated cylinder.
Note: If the Silver 1
Powder Pillow is wetted
with water at this point,
the powder will not
dissolve completely, and
color development will
be inhibited.
7.
Fill a 10-mL cell
to the 10-mL line
with the mixture (the
blank). Add the
contents of one
Thiosulfate Powder
Pillow. Swirl for 30
seconds to mix.
Note: It is important to
have a blank for each
sample.
5.
Add the contents
of one Silver 2
Reagent Pillow to the
cylinder. Swirl to
completely wet the
powder.
Note: If clumps of dry
powder are present
when the sample is
poured in, the powder
will not dissolve
completely, and color
development will be
inhibited.
8.
Fill a second
10-mL cell to the 10-
mL line with the
mixture (the prepared
sample).
57-40
6.
Using a 50-mL
graduated cylinder,
add 50-mL of sample
(adjusted to pH 9-10)
to the mixing cylinder
from Step 5. Stopper
and invert repeatedly
for one minute to mix.
Note: For proof of
accuracy, use a
0.50 mg/L silver
standard solution
(preparation given in
Accuracy Check) in
place of the sample.
2 minutes
9.
Wait 2 minutes.