62 63
Hardness Mg
• Fill both cuvettes up to the 10 mL mark.
• Add 1 drop of HI 93719C-0 EDTA solution to one cuvette (# 1),
replace the cap and invert the cuvette several times to mix. This is
the blank.
• Add 1 drop of HI 93719D-0 EGTA solution to the second cuvette
(# 2), replace the cap and invert the cuvette several times to
mix. This is the sample.
• Place the blank (# 1) into the holder and close the lid.
• Press ZERO key. The meter will show “-0.0-” when the meter is zeroed and ready for measurement.
• Remove the blank (# 1), insert the sample (# 2) into the instrument,
and close the lid.
• Press READ to start the reading. The instrument displays concentration
in mg/L of magnesium hardness, as CaCO
3
.
10 mL 10 mL
# 1
# 1
# 1
# 2
# 2
# 2
Hardness Mg
MAGNESIUM HARDNESS
SPECIFICATIONS
Range 0.00 to 2.00 mg/L
Resolution 0.01 mg/L
Accuracy ±0.11 mg/L ±5% of reading
Typical EMC ±0.02 mg/L
Deviation
Light Source Tungsten lamp with narrow band interference filter @ 525 nm
Method Adaptation of the
Standard Methods for the Examination of Water and Wastewater,
18
th
edition,
EDTA colorimetric method. The reaction between magnesium and reagents
causes a reddish-violet tint in the sample.
REQUIRED REAGENTS
Code Description Quantity
HI 93719A-0 Mg indicator 0.5 mL
HI 93719B-0 Alkali solution 0.5 mL
HI 93719C-0 EDTA solution 1 drop
HI 93719D-0 EGTA solution 1 drop
REAGENT SETS
HI 93719-01 Reagents for 100 tests
HI 93719-03 Reagents for 300 tests
For other accessories see page 128.
MEASUREMENT PROCEDURE
• Select the
Magnesium Hardness
method using the procedure de-
scribed in the
Method Selection
section (see page 12).
• Rinse a graduated beaker several times with unreacted sample,
before filling it to the 50 mL mark with the sample.
• Add 0.5 mL of HI 93719A-0 Magnesium indicator solution, then
swirl to mix.
• Add 0.5 mL of HI 93719B-0 Alkali solution and swirl to mix. Use
this solution to rinse 2 cuvettes.
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