Hanna Instruments HI 83099 User Manual

Page 30

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 at 25 °C

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,

edition, EDTA colorimetric method. The reaction between magnesium and reagents

causes a reddish-violet tint in the sample.

REQUIRED REAGENTS

Code

Description

Quantity

HI 93719

A-0

Mg indicator

0.5 mL

HI 93719

B-0

Alkali solution

0.5 mL

HI 93719

C-0

EDTA solution

1 drop

HI 93719

D-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 132.

MEASUREMENT PROCEDURE

• Select the

Magnesium Hardness method using the procedure

described 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.

Hardness Ca

Note: This test will detect any calcium contamination in the beaker, measuring syringes or sample cells. To

test cleanliness, repeat the test multiple times until you obtain consistent results.

Note: For better accuracy wash glassware with HCl 6N.

SAMPLE DILUTION

This meter is designed to determine low levels of hardness, typically found in water purification systems.
When testing some other sources of water, it is not uncommon to come across levels of hardness that are
greater than the range of this meter.
This problem can be overcome through dilution. Dilutions must be performed with hardness-free water or the
readings will be erroneous.
A dilution to reduce the level of hardness by a factor of one hundred is performed as follows:
• Fill a 1 mL syringe with the sample.
• Place the syringe in a 50 mL beaker, making sure that the beaker is clean and empty, and inject

0.5 mL into the beaker.

• Fill the beaker up to the 50 mL mark with hardness-free water.

INTERFERENCES

Interference may be caused by excessive amounts of heavy metals.

• Press the

Unit key to change the current measurement unit. The results can be converted to French

degrees (°f), German degrees (°dH) and English degrees (°E).

• Press ▲ or ▼ to return to the measurement screen.