Hach DR/850, Procedures Manual, Page: 237 / 460

237
Using AccuVac Ampuls
1.
Enter the stored
program number for
high range nitrate
nitrogen (NO
3
¯–N)
AccuVac Ampuls.
Press:
PRGM
The display will show:
PRGM ?
Note: For most accurate
results, perform a Reagent
Blank Correction using
deionized water (see
Section 1).
2.
Press:
50 ENTER
The display will show
mg/L, NO3-N and the
ZERO icon.
Note: For alternate forms
(NO
3
), press the
CONC key.
3.
Collect at least 40
mL of sample in a
50-mL beaker. Fill a
NitraVer 5 Nitrate
AccuVac Ampul with
sample. Place a stopper
over the tip of the ampul.
Note: Keep the tip immersed
while the ampul fills. The
ampul will not fill
completely.
Note: Adjust the pH of
stored samples before
analysis.
4.
Press:
TIMER ENTER
A one-minute mixing
period will begin. Invert
the ampul repeatedly
back and forth until the
timer beeps. Wipe off
any liquid or fingerprints.
Note: Mixing time and
technique influence color
development. For most
accurate results, do
successive tests on a
standard solution and
adjust the mixing time to
obtain the correct result.
5.
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 results.
Note: An amber color will
develop if nitrate nitrogen
is present.
6.
Fill a sample cell
with at least 10 mL of
sample (the blank).
7.
When the timer
beeps, place the blank in
the cell holder. Tightly
cover the sample cell
with the instrument cap.
8.
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.
NITRATE, High Range,
continued