Hach DR/850, Procedures Manual, Page: 185 / 460

185
Method 8030
HARDNESS
(0 to 4.00 mg/L Ca and Mg as CaCO
3
) For water, wastewater, seawater
Calcium and Magnesium; Calmagite Colorimetric Method
1.
Enter the stored
program number for
magnesium hardness
(as CaCO
3
).
Press:
PRGM
The display will show:
PRGM ?
Note: Adjust the pH of
stored samples before
analysis.
Note: For most accurate
results, perform a Reagent
Blank Correction using
deionized water (see
Section 1).
2.
Press:
30 ENTER
The display will show
mg/L, CaCO3 and the
ZERO icon .
Note: For alternate forms
(Mg, MgCO
3
), press the
CONC key.
3.
Pour 100 mL of
sample into a 100-mL
graduated mixing
cylinder.
Note: The sample
temperature should be
21-29 °C (70-84 °F).
4.
Add 1.0 mL of
Calcium and
Magnesium Indicator
Solution using a 1.0-mL
measuring dropper.
Stopper. Invert several
times to mix.
5.
Add 1.0 mL of Alkali
Solution for Calcium
and Magnesium Test
using a 1.0-mL
measuring dropper.
Stopper. Invert several
times to mix.
Note: If the sample turns
read after adding Alkali
Solution, dilute sample 1:1
and repeat analysis.
6.
Pour 10 mL of the
solution into each of
three sample cells.
Note: The test will detect
any calcium or magnesium
contamination in the mixing
cylinder, measuring
droppers or sample cells. To
test cleanliness, repeat the
test multiple times until you
obtain consistent results.
7.
Add one drop of
1 M EDTA Solution to
one cell (the blank).
Swirl to mix.
8.
Add one drop of
EGTA Solution to
another cell (the
prepared sample).
Swirl to mix.