Hach DR/850, Procedures Manual, Page: 236 / 460

236
5.
Press:
TIMER ENTER
A one-minute reaction
period will begin. Shake
the sample cell
vigorously until the
timer beeps.
Note: It is important to
shake the cell vigorously.
Shaking time and technique
influence color
development. For most
accurate results, do
successive tests on a
standard solution and
adjust the shaking time to
obtain the correct result.
6.
After the timer beeps,
the display will show:
5:00 TIMER 2
Press:
ENTER
A five-minute reaction
period will begin.
Note: A deposit will remain
after the reagent dissolves
and will not affect test
results.
Note: An amber color will
develop if nitrate nitrogen
is present.
7.
Fill another cell with
10 mL of sample (the
blank). Wipe off any
fingerprints or liquid.
8.
Place the blank into
the cell holder. Tightly
cover the sample cell
with the instrument cap.
9.
When the timer
beeps, press
ZERO.
The cursor will move to
the right, then the
display will show:
0.0 mg/L NO3-N
Note: If Reagent Blank
Correction is on, the
display may flash “limit”.
See Section 1.
10.
Place the prepared
sample into the cell
holder. Tightly cover the
sample cell with the
instrument cap.
11.
Press:
READ
The cursor will move to
the right, then the result
in mg/L NO
3
-N (or
alternate form) will
be displayed.
Note: Use of the Standard
Adjust feature for each new
lot of reagent is highly
recommended. See
Accuracy Check .
Note: Rinse the sample cell
immediately after use to
remove all cadmium
particles. Save the spent
sample for proper
hazardous waste disposal
for cadmium.
NITRATE, High Range,
continued