The free fatty acids (FFA) in edible oils can be determined by thermometric titration. Since the exothermic reaction between the FFA and alcoholic TBAOH is too weak, a catalytically enhanced thermometric titration is used. The catalyst acts as an indicator for the endpoint. For the FFA titration, paraformaldehyde is used as a catalyst due to the endothermic hydrolysis of the paraformaldehyde in the presence of excess hydroxide ions. This results in a strongly exothermic endpoint, which can be detected reliably.
