Hach DR/850 Procedures Manual page 227

Nitrogen, Free Ammonia and Chloramine (Mono), continued
FA
17.
Add the contents
of one pillow of
Monochlor F to the cell
for the Free Ammonia
measurement.
Cap and shake the cell
about 20 seconds to
dissolve the reagent.
Note: The reaction period
indicated in step 11 must be
complete before the
addition of Monochlor F to
the cell for free ammonia
measurement.
FA
Tab
Slot
21.
Place the Free
Ammonia cell into the
instrument so that the
cell tab is at the
two-o'clock position.
Make sure the sample
cell tab is completely
seated in the cell holder
slot.
Tightly cover the sample
cell with the instrument
cap.
18.
Cap and shake the
cell about 20 seconds to
dissolve the reagent.
A green color will form
if ammonia or
monochloramine is
present.
22.
Press:
READ
The cursor will move
to the right, then
the result in mg/L free
ammonia as nitrogen
(NH –N) or chosen units
3
will be displayed.
19.
Press:
TIMER ENTER
A five-minute reaction
period will begin.
Note: The color
development time depends
on the sample temperature.
See Table 1.
227
20.
After the timer has
expired, press:
EXIT