Hach DR/850, Procedures Manual, Page: 186 / 460

186
Sampling and Storage
Collect samples in acid-washed plastic bottles. Adjust the sample
pH to 2 or less with nitric acid (about 5 mL per liter). Preserved
samples can be stored up to six months. Adjust the sample pH to
9.
Place the blank into
the cell holder. Tightly
cover the sample cell with
the instrument cap.
10.
Press:
ZERO
The cursor will move to
the right, then the
display will show:
0.00 mg/L CaCO3
Note: If Reagent Blank
Correction is on, the
display may flash “limit”.
See Section 1.
11.
Place the prepared
sample into the cell
holder. Tightly cover the
sample cell with the
instrument cap.
12.
Press:
READ
The cursor will move to
the right, then the result
in mg/L magnesium
hardness (as CaCO
3
)
will be displayed.
13.
Without removing
the cell, press:
PRGM 29 ENTER
The display will show:
PRGM ?
Note: For alternate forms
(Ca) press the CONC key.
14.
Press:
ZERO
The cursor will move to
the right, then the
display will show:
0.00 mg/L CaCO3
15.
Place the third
sample cell into the
cell holder.
16.
Press:
READ
The cursor will move to
the right, then the result
in mg/L calcium
hardness (as CaCO
3
)
will be displayed.
Note: Standard Adjust may
be performed using a
prepared standard (see
Section 1).
Note: mg/L total hardness
= mg/L Ca as CaCO
3
+
mg/L Mg as CaCO
3
.
HARDNESS,
continued