Question

In the experiment analyzing fatty acids in oils and fats using gas chromatography, extraction of fatty acid content was done from commercial oils and fats.

Suggest a reason for the purpose of NaCl at step 3

Steps for extraction method:

1) Take enough material so that you have 0.1g of fat and add to boiling tube

2) Add 5ml CHCl3/MeOH and use foil to cover up and then vortex

3) Add 2ml NaCl solution and re-vortex

4) Transfer 500ul of the bottom layer into screw top tube

5) Add 3ml 3M HCl/MeOH and mix then heat in an oven for 1 hour

6) Transfer the mixture to a clean tube and add 6ml of water and 3ml of hexane

7) Shake and then allow to settle before adding 500ul of the top layer into an autosampler vial for GC-MS analysis

Answer 1

NaCl solution is an aqueous solution act as a brine solution. It is generally used to remove any small amount of water present in the organic phase. In this lipid extraction procedure, we are trying to dissolve all the lipid content from the sample in solvent system CHCl3+MeOH. However, there is a chance that the sample may contain some small amount of water. Although water is immiscible in chloroform, it is difficult to see the two layers. Hence, remove this small amount of water we use a NaCl solution.