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Determination of Water Content in Alkyl-2-cyanoacrylate Using Karl Fischer Titration

Product Group

Esters of carboxylic acids, Technical products

General Information concerning the product group

Esters of carboxylic acids

Esters of carboxylic acid can be analysed analogously to the hydrocarbons according to standard Karl Fischer methods. Long-chain compounds require the addition of solubilisers, e.g. long-chain alcohols or chloroform. Unsaturated compounds can usually be titrated in the same way. Recommended methods are both the volumetric titration with one or two component reagents, as well as the coulometric analysis. The latter is predominantly applied for low water concentrations (< 0.1 %).

Technical products

This product group comprises the most diverse products. Depending on solubility, their behaviour in the KF solution and water content, different Karl Fischer methods apply.

Special Information concerning the sample and the methods

Cyanoacrylates polymerise if they come into contact with air. For KF titration the addition of solubilisers is necessary. Toluene is particularly suitable here. In addition the hygroscopic properties of these substances should be taken into account. Water determination of methyl-2-cyanoacrylate, the most reactive of these substances, poses some difficulties. Here polymerisation already commences with addition of the KF solvent. Agglomeration and coagulation of the sample coat the electrode and lead to dragging end points and overtitration.

Titration one component system

Reagents:

Titrant
188002 Aquastar™ - CombiTitrant 2 - One component reagent for volumetric Karl Fischer titration, 1 mL = approx. 2 mg water
or
188001 Aquastar™ - CombiTitrant 1 - One component reagent for volumetric Karl Fischer titration, 1 mL = approx. 1 mg water

Solvent
50 mL 188020 Aquastar™ - CombiSolvent oils - Solvent for volumetric Karl Fischer titration with one component reagents for oils

Titration Parameters:
Stirring time: 60 sec.
Default titration settings, e.g.:
I(pol) = 20 - 50 µA, U(EP) = 100 - 250 mV
Stop criterion for fast titration: drift < 30 µL/min

Sample size:
0.5 - 2 g

Procedure:
The titration medium is first placed into the titration cell and titrated dry by means of the titrant. Then the sample is added with a syringe (exact sample weight determination by weighing of syringe before and after injection) or directly from the sample flask and the titration is started. Titration is carried out to fast end point. After the determination both the cell and the electrode should be thoroughly cleaned.

Materials

     
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