Hach DR/850, Procedures Manual, Page: 203 / 460

203
Method 8365
IRON, TOTAL
(0 to 1.80 mg/L)
For cooling water with molybdenum-based treatment
FerroMo
™
Method
*
1.
Enter the stored
program number for
iron (Fe).
Press:
PRGM
The display will show:
PRGM ?
Note: For most accurate
results, perform a Reagent
Blank Correction using
deionized water (see
Section 1).
Note: Adjust the pH of
stored samples before
analysis.
2.
Press:
38 ENTER
The display will show
mg/L, Fe and the
ZERO icon .
Note: Determination of
total iron requires
digestion; see Section 2.
3.
Fill a 50-mL
graduated mixing
cylinder with 50 mL
of sample.
Note: Sample pH is
important in the test; see
Interferences.
Note: Rinse glassware with
1:1 Hydrochloric Acid
Solution. Rinse again with
deionized water. This
removes iron deposits
which can cause slightly
high results.
4.
Add the contents of
one FerroMo Iron
Reagent 1 Powder
Pillow to the graduated
cylinder. Stopper and
invert several times to
mix. Remove the
stopper. This is the
prepared sample.
5.
Transfer 25 mL of
the prepared sample to a
sample cell.
6.
Add the contents of
one FerroMo Iron
Reagent 2 Powder
Pillow to the sample
cell. Cap the cell and
shake for 30 seconds.
This is the prepared
sample.
7.
Press:
TIMER ENTER
A three-minute reaction
period will begin.
Note: A blue color will
develop if iron is present.
8.
Fill a second sample
cell with 25 mL of the
prepared sample from
Step 4 (the blank).
* Adapted from G. Frederic Smith Chemical Company, The Iron Reagents , 3rd ed. (1980).