Determination of free ethanolamine and ester amine

The free ethanolamine is particularly important in Kritchevsky materials. The ethanolamine (and DHEP if present) is extracted into an aqueous solution, leaving any ester amine in the organic layer [22]. If free fatty acid is present it is extracted as soap, but it does not interfere. This is a simple and direct approach for use when the more comprehensive analysis described in the next two sections is not required. 

Weigh a 5 g sample in a 250 ml separating funnel. Add 100 ml diethyl ether and 100 ml 10% sodium chloride. Shake and allow to separate. Re-extract the aqueous layer with 50 ml ether and collect the aqueous layer in a 400 ml beaker. Wash the ether layers in turn with 50 ml of the salt solution, collecting the washings in the same beaker. 

Make the aqueous solution just alkaline to phenolphthalein and titrate potentiometrically with 0.5 M hydrochloric acid through two endpoints at high and low pH, or first to phenolphthalein and then to bromophenol blue. 

Evaporate the ether to dryness (caution flammable vapour). Dissolve the residue in glacial acetic acid and titrate with 0.1 M perchloric acid (see section 6.6.4). 

The titration at step 2 determines the free ethanolamine and the titration at step 3 the ester amine. 

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