Hach DR/700 Procedures Manual page 523

IRON, TOTAL,
10.
Insert the
AccuVac Vial
Adapter into the cell
holder.
SAMPLING AND STORAGE
Collect samples in acid-washed glass or plastic bottles. Adjust the
sample pH to 2 or less with Nitric Acid (about 2 mL per L). Store
samples preserved in this manner up to six months at room temperature.
If reporting only dissolved iron, filter the sample immediately after
collection and before addition of nitric acid.
Before testing, adjust the pH of the stored sample to between 3 and 4
with 5.0 N Sodium Hydroxide Standard Solution. Do not exceed pH 5
as iron may precipitate. Correct the test result for volume addition; see
Sampling and Storage, Volume Additions (Section I).
continued
11.
Within 30
minutes after the 3-
minute waiting
period, place the
prepared sample in
the cell holder.
Note: In bright sunlight
it may be necessary to
close the cell
compartment cover.
57-17
12.
Press:
READ
The display will
count down to 0.
Then the display will
show the results in
mg/L iron (Fe).
Note: For most accurate
results, run the
procedure using iron-
free demineralized
water, instead of
sample, in Step 4.
Subtract the value
obtained in Step 12 from
all later tests. Repeat
for each new lot of
AccuVac reagent.