Hach DR/850 Procedures Manual page 250

NITRITE, Low Range,
5.
Press:
TIMER ENTER
A 15-minute reaction
period will begin.
Note: A pink color will
develop if nitrite is present.
9.
Place the prepared
sample into the cell
holder. Tightly cover the
sample cell with the
instrument cap.
continued
6.
When the timer
beeps, fill an empty
sample cell with 10 mL
of sample (the blank).
10.
Press:
READ
The cursor will move to
the right, then the result
in mg/L nitrite nitrogen
(or an alternate form)
will be displayed.
7.
Wipe the outside of
the sample cell with a
towel. Place the blank
into the cell holder.
Tightly cover the sample
cell with the instrument
cap.
Note: Wiping with a damp
cloth, followed by a dry
pne, removes fingerprints
and other marks.
250
8.
Press:
ZERO
The cursor will move to
the right, then the
display will show:
0.000 mg/L NO2-N
Note: If Reagent Blank
Correction is on, the
display may flash "limit."
See Section 1.