Karl Fischer Titrators

The C20 and C30 are available with two different coulometer cells – with or without a diaphragm. For most applications, we recommend the cell without the diaphragm because it is almost maintenance-free. Due to its innovative design, this diaphragm-free cell from METTLER TOLEDO can even be used for the determination of water in oils.

The version of the cell with a diaphragm is recommended for applications such as the determination of moisture in substances containing ketones. It is also recommended if the best possible accuracy is required.

The most practical solution to this question is to add some blue silica gel to the top of the drying tube to serve as an indicator. As soon as the first trace of pink appears in this gel layer, it is time to change or regenerate the molecular sieve. Naturally, an increase in background drift can also indicate that it is time to replace the molecular sieve.

The first and most obvious answer to this question is that the solvent should be replaced as soon as the sample no longer dissolves. This, however, is only one of the reasons for changing the solvent. A second less obvious reason applies in the case of two component reagents where the titrant contains iodine, and the solvent contains all the other components necessary for the Karl Fischer reaction. One of these other components is sulfur dioxide and this can become depleted long before the dissolving capacity of the solvent is exceeded. As a general rule the solvent in these two component systems has an approximate water capacity of 7mg of water per mL of solvent. This means that in theory 40mL of solvent can accommodate 280mg of water before the solvent needs to be changed. As the typical titrant has a concentration of 5mg/mL, 280mg of water would require 56mL of titrant.

No, the InMotion™ KF oven can only be used with the Compact V30S as well as the T7 and T9 Excellence titrators

To reduce the drift value, make sure all the openings on the titrator have been greased (e.g. tube inserts, electrodes, adapters, etc.) and that you use dry and fresh molecular sieves and silica gel in your drying tubes. We recommend exchanging your molecular sieves every 6 weeks. If you still have high values, try to gently shake the titration vessel to collect traces of water from the glass walls.

The Compact C10/20/30SX Karl Fischer titrators do not possess a diaphragm. Without it, there’s no risk of getting it clogged and, hence receiving incorrect results. The C10/20/30SD Compact titrators possess a diaphragm, which can improve the drift value.