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Chapter 3: Variations of Karl Fischer Titration
Reagents: Aldehydes & Ketones
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Historically, aldehydes and ketones have posed problems for Karl Fischer titration as they react with some conventional reagents to produce acetals and ketals [1]. The water formed in this reaction is also titrated, leading to erroneously high results and vanishing end points. Additionally, a second side reaction, the well-known bisulfite addition, can occur during the titration of aldehydes. This unwanted side reaction consumes water and leads to erroneously low results [1].
We have developed and patented HYDRANAL® reagents for aldehydes and ketones that do not produce side reactions and therefore eliminate or significantly reduce these sources of error. These innovations include specific amines and alcohols not found in competitive Karl Fischer reagent formulations.
These HYDRANAL® reagents can also be used for determination of water in substances other than aldehydes and ketones. HYDRANAL®-Medium K, HYDRANAL®-Working Medium K and HYDRANAL®-KetoSolver can act as solvent for determination of water in any substance where methanol interferes with the titration and must be avoided.
HYDRANAL®-Composite 5 K can be used as a universal titration agent. It does, however, show a slower titration rate than HYDRANAL®-Composite 5. In many cases, HYDRANAL®-Medium K can be used in conjunction with the standard volumetric reagent, HYDRANAL®-Composite 5. For determination of water in aldehydes and certain reactive ketones the use of HYDRANAL®-Composite 5 K is strongly recommended.
HYDRANAL®-Coulomat AK is an anolyte for the coulometric determination of water in ketones. It contains imidazole, sulfur dioxide and iodide dissolved in a suitable solvent mixture. Its capacity is approximately 100 mg of water per 100 mL. HYDRANAL®-Coulomat CG-K is the corresponding catholyte, free of halogenated hydrocarbons.
Product range HYDRANAL® reagents for aldehydes and ketones
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