What Substances Interfere with Karl Fischer Moisture Analyzer Testing?

Many factors affect Karl Fischer moisture analyzer (trace moisture analyzer) testing. Beyond the method itself, we must consider whether the sample is suitable: some substances are unsuitable, and during testing some substances distort the data and accuracy. It is therefore essential to understand these interfering factors.

1. Salts, hydroxides, and oxides.

For example:Na2CO3+HI→NaI+CO2+H2O, Ca(OH)2+H2SO4→CaSO4+H2O, MgO+HI→MgI2+H2, and other substances such as Ag2O, HgO, MnO2, PbO2, and ZnO.

2. Ketones and aldehydes combine with the methanol in Karl Fischer reagent, forming ketals and acetals and releasing water.

Such substances are not easily measured byKarl Fischerbut can be measured byKarl Fischervolumetric titration. By changing the composition of theKarl Fischerreagent—for example, replacing methanol with ethylene glycol monomethyl ether or2-methoxyethanol—good results can be obtained. Note that not all ketones and aldehydes are unsuitable for coulometric determination; substances such as formaldehyde, diisopropyl ketone, acetophenone, and benzoin do not react to release water when they enterKarl Fischerthe reagent. Given that the volumetric Karl Fischer method of the Karl Fischer moisture analyzer can achieve an accuracy of10-4 level, for enterprises producing ketones and aldehydes, the volumetric Karl Fischer method is still recommended as long as it meets their requirements.

3. Strong acids react withKarl Fischerthe methanol in the reagent, releasing water2CH3OH+H2SO4→（CH3O）SO2+H2O，CH3OH+HOOCH→CH3O-OCH+H2O。

4. In a Karl Fischer moisture meter, boron compounds, boric acid, and methanol can also produce water through esterification.

Iodine-consuming substances.These substances react with the iodine in iodine-containing reagents, leading to falsely high water content—examples include iron salts, copper salts, nitrites, thiosulfates, and related products: volumetric moisture analyzers, Karl Fischer moisture analyzers, coulometric moisture analyzers, halogen moisture analyzers.

Karl Fischer moisture analyzers can test many substances, but not all of them. Before testing, we need to understand what the substance is, so that accurate results can be obtained.For more, the VicoMeter moisture analyzer website will continue to update for you, with more content available on the VicoMeter moisture analyzer websitehttps://www.weikemeituo.com/Halogen Moisture Analyzers_Karl Fischer Moisture Analyzers_Density Meters_Electronic Balances_Moisture Analyzers for Lithium Batteries, Wood, Wood Chips, Gases, Solids and Liquids—VicoMeter | Jiangsu Victor Instrument Meter Co., Ltd.!