Sample preparation for Karl Fischer Titrandos and Titrino Coulometers

KF Titrando Sample Preparation

The water content of some samples cannot be determined directly with titration.

For such cases, Metrohm offers various techniques that allow you to prepare samples for coulometric or volumetric water determination.

Key features

  • If your samples don’t dissolve easily, use the oven method.
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  • If the water is difficult to extract from the sample, use azeotropic distillation.
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  • If your samples are solid, use the Polytron homogenizer.
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  • If you have a high sample throughput, automate sample preparation and analysis.
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For difficult samples: the oven method

The oven method allows you to analyze samples that cannot be titrated directly.

For instance, if your samples have poor solubility or if side reactions with the KF reagent occur, then the oven method may be a suitable solution. In this method, the samples are heated and the evaporated water is transferred to the titration cell with a dry carrier gas. As a result, only the water gets in contact with the cell, thus preventing contamination of the cell and the electrode.

Manual, automated, or software-controlled: your choice

You can implement the oven method just the way you need it.

The 860 KF Thermoprep: This manually operated instrument offers you a simple, straightforward, and affordable solution.

The 885 Compact Oven Sample Changer: This automated sample changer combines the oven method with time savings and ease of use. Thanks to the integrated control panel, complicated parameter settings are not required. You just have to set the gas flow, the temperature, and the number of samples and you’re ready to go.

The 874 USB Oven Sample Processor: Like the titrator, this automated sample processor is controlled with the tiamo software. This enables you, for instance, to record the heating curve of an unknown sample to determine the optimum temperature for the analysis. Moreover, with this instrument, you can automate reagent exchange and thus make your work safer, as you don’t get in contact with the toxic reagent.

Azeotropic distillation with the KF Evaporator

For some samples, such as crude oil, tar, turpentine, resins, or terpenes, simple evaporation does not work.

In such cases, azeotropic distillation with the KF Evaporator can be applied. A solvent is added to the sample, the sample is heated, and the evaporated mixture is transferred to the titration cell and analyzed. As the sample does not enter the titration cell, contamination of the cell or the electrode is prevented.

Homogenization for analyzing solid samples

If you need to analyze solid samples, then you can use the high-quality Polytron homogenizer.

This homogenizer enables you to achieve thorough homogenization and consistent results.

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