Method for determining the moisture content in a sample using sulfonic acid

By adding a sulfonic acid reagent system to the Karl Fischer titration method, the problem of unstable stoichiometry in alcohol solutions and aprotic solutions was solved, and high-precision water determination in different solvents was achieved.

CN116324404BActive Publication Date: 2025-10-24SOZOTEX PERFORMANCE MATERIALS AMERICA INC
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Patent Information

Application Number
CN202180068489.4
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Priority Date
2021-10-22
Filing Date
2021-10-28
Publication Date
2025-10-24
Estimated Expiration
2041-10-28

AI Technical Summary

Technical Problem

The existing Karl Fischer titration method suffers from stoichiometric instability in alcoholic and aprotic solutions, leading to inaccurate water determination results, especially due to unwanted side reactions affecting the stoichiometric ratio of iodine to water.

Method used

A reagent system comprising sulfur dioxide or its derivatives, a base, a hydrogen halide donor, a solvent and a sulfonic acid is used. The sulfonic acid is added to stabilize the stoichiometry of the Karl Fischer reaction, inhibit unwanted side reactions, and ensure that the stoichiometric ratio of iodine to water is 1:1.

Benefits of technology

It achieves highly accurate moisture determination in alcoholic and non-alcoholic solvents, improving the accuracy and stability of moisture content determination.

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Abstract

A first method for determining moisture content in a sample includes the steps of providing a reagent comprising sulfur dioxide or a derivative thereof; a base; optionally a hydrogen halide or a hydrogen halide donor; a solvent; and a sulfonic acid; and titrating the sample with the reagent. A second method for determining moisture content in a sample includes the steps of providing the reagent described above, mixing the sample with the reagent; and adding an iodine source to the sample and / or the reagent. The reagent can alternatively consist essentially of sulfur dioxide or a derivative thereof; imidazole and / or a derivative thereof; optionally a hydrogen halide or a hydrogen halide donor; acetonitrile; methanesulfonic acid; and methanol and / or ethanol.
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