MACHEREY-NAGEL visocolor HE Total Hardness H2 Test Kit User Manual
- June 3, 2024
- MACHEREY-NAGEL
Table of Contents
MACHEREY-NAGEL visocolor HE Total Hardness H2 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 dropwise while smoothly shaking the test tube. As soon as the red color turns lighter, drop more slowly until the solution turns completelygreen. Read off total hardness in °d or mmol/L from the syringe barrel (lower rim of the black plunger O-ring). Color changes followed easily when holding test tube before a light background (e.g. sheet of white paper). For the expression in °e, multiply 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 totalhardness 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 download 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 copperpipes, let the water run for a sufficient amount of time beforetaking the sample.
Note:
For the determination of total hardness in the presence of copper ions, please contact MACHEREY-NAGEL for special working instructions
MACHEREY-NAGEL GmbH & Co. KG · Valencienner Str. 11 · 52355 Düren · Germany
Tel.: +49 24 21 969-0 · info@mn-net.com · www.mn-
net.com
References
Read User Manual Online (PDF format)
Read User Manual Online (PDF format) >>