Determination of fatty acid, taurine and methyltaurine

The amide is acid-hydrolysed and the hydrolysis products are separated and determined. Amides resist hydrolysis and require prolonged boiling at high temperature with a high concentration of acid. The fatty acid is extracted and the amino acid determined by acid titration. The same procedure can also be used for sarcosinates. 

Place 5g sample in a pressure vessel with 50 ml 6M hydrochloric or 5M sulphuric acid, seal and heat in an oven at 160-180°C for 6h. Allow to cool to room temperature before cautiously opening the pressure vessel. 

Transfer the solution quantitatively to a separating funnel and extract the fatty acid with petroleum ether. Keep the aqueous layer. 

Evaporate the petroleum ether extract to dryness. Dry, cool and weigh the fatty acid. 

Neutralise the aqueous layer to phenolphthalein with 5 M alkali, then make just alkaline. (Caution the solution will become hot during neutralisation. Add the alkali a little at a time, with continuous cooling.) 

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