Determination of Free fatty Acid by Titration Method

The free fatty acid is determined by titrating the sample in ethanol with standard aqueous sodium hydroxide using a phenolphthalein indicator solution.

APPARATUS

250 ml Erlenmeyer Flask

100 ml Measuring Cylinder

50 ml Burette

REAGENTS

Ethanol 95% v/v

Phenolphthalein Indicator Solution, prepared by Test Method

Preparation of Phenolphthalein Indicator Solution.

0.1M Sodium Hydroxide, prepared under Test Method.

Standardization of Sodium Hydroxide Solution

Procedure

Accurately weigh about 10 g of sample into a 250 ml Erlenmeyer flask (gram). 

Measure 100 ml of ethanol into a 250 ml Erlenmeyer flask, add 1 ml phenolphthalein indicator solution, and titrate to a faint pink colour with 0.1M sodium hydroxide. 

If the ethanol is already alkaline to phenolphthalein, add sufficient 0.1M hydrochloric acid to dissipate the pink colour and then titrate with 0.5M sodium hydroxide to a faint pink colour.

Add the neutralized ethanol to the Erlenmeyer flask containing the sample, warm it, and swirl to dissolve the sample. 

Titrate with 0.1M sodium hydroxide to a faint pink colour (V).

CALCULATION OF FREE FATTY ACID

where V is the volume of NaOH.

M NaOH is the molarity of the NaOH.

M Fatty Acid is the molar mass of the fatty acid.

Calculate the result as Palmitic Acid, M = 256.43 g/mole. Calculate the result as lauric acid, M =200,32 g/mole,m is the mass of the sample.