Macherey-nagel Visocolor He Total Hardness H 2 Test Kit User Manual

MACHEREY-NAGEL Visocolor HE Total Hardness H 2 Test Kit

Method

Complexometric titration
Contents of test kit (*refill pack)

• sufficient for 200 tests with an average hardness of 1.0 °d
• 15 mL indicator solution H 2* 100 mL titration solution TL H 2*
• 1 test tube with ring mark
• 1 titration syringe 0–2.0 °d resp. 0–0.36 mmol/L
• (1 graduation mark ≜ 0.05 °d resp. 0.01 mmol/L)
• 2 plastic dropping tips

Hazard warning
Information regarding safety can be found on the box’ label and in the safety data sheet. You can download the SDS from www.mn-net.com/SDS.

Procedure

1. Rinse test tube several times with the test sample and fill to ring mark.
2. Add 2 drops indicator solution H 2 and shake. The test sample turns red. If sample turns green, the hardness is < 0.05 °d.
3. Put dropping tip onto the titration syringe, press down plunger, dip the tip into the titration solution TL H 2 and draw up plunger slowly, until the lower rim of the black plunger O-ring agrees with value 0 on the barrel scale. The small air pocket below the plunger tip does not disturb the determination.
4. Addition of the titration solution: We recommend taking the syringe in the left hand and the test tube in the right hand (see drawing) and adding titration solution drop-wise while smoothly shaking the test tube. As soon as the red color turns lighter, drop more slowly until the solution turns completely green.
5. Read off total hardness in °d or mmol/L from the syringe barrel (lower rim of the black plunger O-ring). Color change is followed easily when holding test tube before a light background (e.g. sheet of white paper). For the expression in °e, multi ply
6. the result in German degrees with 1.25.
   If the first syringe filling isn’t enough to reach color change (hardness > 2 °d), fill syringe once more with titration solution TL H 2 and titrate to color change (as above). Read off total hardness and add for each used syringe filling 2 °d.

This method cannot be applied for the analysis of sea water.
Disposing of the samples
Information regarding disposal can be found in the safety data sheet. You can down-load the SDS from www.mn-net.com/SDS.
Interferences
Copper(II) ions may delay the indicator change, or even block this change if higher levels are present. Therefore, in the case of copper pipes, let the water run for a sufficient amount of time before taking the sample.
Note
For the determination of total hardness in the presence of copper ions, please con-tact MACHEREY-NAGEL for special working instructions.

MACHEREY-NAGEL GmbH & Co. KG
Valencienner Str. 11
52355 Düren Germany
Tel: +49 24 21 969-0
[email protected]
www.mn-net.com

References

• MACHEREY-NAGEL Webshop | MACHEREY-NAGEL