Hach DR/700 - Page 214

45-42
POTASSIUM, continued
4. After 2 seconds,
the display will show
a program number,
the concentration
units, decimal
position and the zero
prompt. Press
PROGRAM once or
twice until the lower
display shows
program number
45.000
The upper display
will show the
concentration of a
previous calibration
standard. If desired,
press the
UP ARROW
key to display the
other standard.
5. Make the
displayed standard.
For each mg/L
displayed, pipet 1 mL
from a 250-mg/L
Potassium Voluette
Ampule into a
250-mL volumetric
flask. Add
demineralized water to
the mark. Cap and
invert 10 times to mix.
Note: For example, to
make a 4 mg/L standard,
pipet 4.00 mL of the
250-mg/L standard
solution into the flask.
To make a 0-mg/L
standard, use only
demineralized water.
6. Fill a 25-mL
graduated mixing
cylinder with 25 mL
of the displayed
standard.
7. Add the contents
of one Potassium 1
Reagent Powder
Pillow and the
contents of one
Potassium 2 Reagent
Solution Pillow to
each cylinder. Stopper
and invert several
times until the powder
dissolves.
8. After the solution
clears, add the
contents of one
Potassium 3 Reagent
Powder Pillow to
each cylinder.
Stopper and shake for
30 seconds.
9. Wait 3 minutes.
Note: Complete Steps
10-14 within 7 minutes
after the 3-minute
waiting period.
3 minutes