WP-089
Water content determination in ketones using Hydranal™ NEXTGEN FA reagents
Summary
Ketones react with the alcohol component in Karl Fischer (KF) reagents forming ketals. This reaction releases water, thereby increasing the water content and falsifying the titration results. This side reaction is even more pronounced in coulometric KF titration.
Previous generation coulometric KF reagents only suppress this side reaction to an extent. The Hydranal™ NEXTGEN FA reagents do not contain any alcohol; here, FA is an abbreviation for «free of alcohol». With Hydranal™ NEXTGEN FA reagents, the water content in ketones can be determined quickly and reliably. Compared to other existing KF reagents for ketones on the market, the side reactions are measurably better suppressed when using Hydranal™ NEXTGEN FA reagents.
This White Paper explains the reaction mechanism of these alcohol-free Karl Fischer reagents and which points have to be considered when working with these reagents, such as light influence or ideal titration parameters. Furthermore, the water content in a range of samples was determined using the NEXTGEN FA reagents. Aside from two different water standards, several ketones (including acetone, 1-methyl-2-pyrrolidone, and acetylacetone) were tested. The water content determination in various ketones is shown to be fast and reproducible.