MACHEREY-NAGEL Visocolor HE Total Hardness H 2 Test Kit User Manual
- June 3, 2024
- MACHEREY-NAGEL
Table of Contents
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
- Rinse test tube several times with the test sample and fill to ring mark.
- Add 2 drops indicator solution H 2 and shake. The test sample turns red. If sample turns green, the hardness is < 0.05 °d.
- 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.
- 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.
- 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
- 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.
| °d | °e | °f | mg/L CaO | mg/L CaCO₃ | mmol/L H⁺ |
|---|---|---|---|---|---|
| 1 | 1.3 | 1.8 | 10 | 18 | 0.36 |
| 2 | 2.5 | 3.6 | 20 | 36 | 0.71 |
| 3 | 3.8 | 5.4 | 30 | 54 | 1.07 |
| 4 | 5.0 | 7.1 | 40 | 71 | 1.43 |
| 5 | 6.3 | 8.9 | 50 | 89 | 1.78 |
| 6 | 7.5 | 10.7 | 60 | 107 | 2.14 |
| 7 | 8.8 | 12.5 | 70 | 125 | 2.50 |
| 8 | 10.0 | 14.3 | 80 | 143 | 2.86 |
| 9 | 11.3 | 16.1 | 90 | 161 | 3.21 |
| 10 | 12.5 | 17.8 | 100 | 178 | 3.57 |
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