Hach DR/700 - Page 258

50-8
IRON, FERROUS, continued
4. Fill a 25-mL cell
to the 25-mL line
with sample.
Note: For proof of
accuracy, use a
1.00 mg/L ferrous
standard solution
(preparation given in
Accuracy Check) in
place of the sample.
5. Add the contents
of one Ferrous Iron
Reagent Powder
Pillow to the sample
cell (the prepared
sample). Cap and
invert to mix.
Note: An orange color
will develop if ferrous
iron is present.
Note: Undissolved
powder does not affect
accuracy.
6. Wait 3 minutes.
Note: Steps 7 and 8 can
be completed during
this reaction period.
7. Fill a 25-mL cell
to the 25-mL line
with sample (the
blank). Cap.
8. Place the blank in
the cell holder.
Note: In bright light,
put 10 mL in a 10-mL
cell, insert it and close
the cell compartment
cover.
9. Press: ZERO
The display will
count down to 0.
Then the display will
show 0.00 mg/L and
the zero prompt will
turn off.
3 minutes