User Manual Q&AAnswer
Feb 21, 2025 - 10:39 PM
To use the MACHEREY-NAGEL Visocolor HE Total Hardness H2 Test Kit to measure total hardness in water, follow these steps:
1. Rinse the test tube several times with the water sample you want to test and fill it up to the ring mark.
2. Add 2 drops of the indicator solution H2 to the test tube and shake it. The test sample should turn red. If the sample turns green, it indicates that the hardness is less than 0.05 °d.
3. Attach the plastic dropping tip to the titration syringe. Press down the plunger and dip the tip into the titration solution TL H2. Slowly draw up the plunger until the lower rim of the black plunger O-ring aligns with the value 0 on the barrel scale. The small air pocket below the plunger tip does not affect the determination.
4. Start adding the titration solution drop-wise to the test tube while smoothly shaking it. It is recommended to hold the syringe in your left hand and the test tube in your right hand. As soon as the red color starts to lighten, drop the solution more slowly until it turns completely green.
5. Read off the total hardness in °d or mmol/L from the syringe barrel, specifically the lower rim of the black plunger O-ring. You can easily observe the color change by holding the test tube in front of a light background, such as a sheet of white paper. If you wish to express the result in °e, multiply the value in German degrees by 1.25.
6. If the first filling of the syringe is not enough to reach the color change (indicating hardness greater than 2 °d), refill the syringe with the titration solution TL H2 and repeat the titration process. For each additional syringe filling used, add 2 °d to the total hardness value.
It is important to note that this method cannot be used for the analysis of sea water. If you have copper pipes, it is recommended to let the water run for a sufficient amount of time before taking the sample to avoid interference from copper(II) ions. If you need to determine total hardness in the presence of copper ions, please contact MACHEREY-NAGEL for special working instructions.
For any further questions or assistance, you can contact MACHEREY-NAGEL GmbH & Co. KG at the provided contact information.
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