Hach DR/850, Procedures Manual, Page: 337 / 460

337
Method 10076
pH
(6.5 to 8.5 pH units)
Colorimetric pH Determination Using Phenol Red
For water and wastewater
1.
Enter the stored
program number for the
pH method.
Press:
PRGM
The display will show:
PRGM ?
2.
Press:
75 ENTER
The display will show
PH and the ZERO icon.
3.
Fill a sample cell
with 10 mL of sample
(the blank).
4.
Place the blank in the
cell holder. Tightly
cover the sample cell
with the instrument cap.
5.
Press:
ZERO
The cursor will move to
the right, then the
display will show:
6.0 PH
6.
Fill another cell with
10 mL of sample.
Note: Sample temperature
must be 21-29 °C.
7.
Using a disposable
dropper, add 1 mL of
Phenol Red Indicator
Solution to the cell (the
prepared sample). Cap
the sample cell and
invert twice to mix.
8.
Place the prepared
sample into the cell
holder. Tightly cover the
sample cell with the
instrument cap.