Hach DR/850, Procedures Manual, Page: 216 / 460

216
Sampling and Storage
Collect samples in acid-washed plastic bottles. Manganese may
be lost by adsorption to glass container walls. Adjust the pH to
less than 2 with nitric acid (about 2 mL per liter). Preserved
samples may be stored up to six months at room temperature.
Adjust the pH to 4 to 5 with 5.0 N sodium hydroxide before
analysis. Do not exceed pH 5, as manganese may be lost as a
precipitate. Correct the test result for volume additions; see
Correction for Volume Additions in Section 1 for more
information. If only dissolved Mn is to be determined, filter
before acid addition.
Accuracy Check
Standard Additions Method
a) Snap the neck off a Manganese Voluette Ampule Standard
Solution, 250 mg/L Mn.
b) Use the TenSette Pipet to add 0.1, 0.2 and 0.3 mL of
standard, respectively, to the three 25-mL water samples.
Swirl to mix.
c) Transfer only 10 mL of each solution to the 10-mL sample
cells.
d) Analyze each standard addition sample as described in the
procedure. The manganese concentration should increase
1.0 mg/L for each 0.1 mL of standard added.
9.
Place the prepared
sample into the cell
holder. Tightly cover the
sample cell with the
instrument cap.
10.
Press:
READ
The cursor will move to
the right, then the result
in mg/L manganese will
be displayed.
Note: Standard Adjust may
be performed using a
prepared standard (see
Section 1).
MANGANESE, High Range,
continued