The method determines the fatty acid composition of soap and soap noodles and in oil, analysis of fatty acid composition by gas chromatography, and analysis of the fatty acid composition.
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2. APPARATUS
Chemito 8510 Gas Chromatograph.
Column - 10 ft length 1/8 inch dia, SS made column.
Column - 10% DEGs.
Conditions: Column temperature - 215 deg C constant.
Injector temperature - 225 deg C.
Detector temperature - 250 deg C.
Carrier Gas - Nitrogen.
Run time - 15 minutes.
Burette, Beaker, Oven.
3. REAGENTS
Methyl Orange Solution (0.05% w/v).
Ethyl ether.
Sodium Chloride Solution-saturated.
Acetone.
Sulphuric acid.
Thionyl chloride.
Sodium sulfate.
4. Procedure
Fatty acid extraction from soap and soap noodles
4.1 Dissolve 5 gm of the grated sample in 100 ml of
distilled water by warming in a 250 ml conical flask in a water bath.
4.2 Add 2 to 3 drops of methyl orange solution (0.05% w/v in
alcohol)
4.3 Add dilute Sulphuric Acid (1:1) till the color changes
to pink.
4.4 Insert a small funnel into the neck of the flask, and
heat the flask to a temperature not exceeding 60 °C until the fatty acids
separate as a clear layer.
4.5 Add 50 ml of saturated sodium chloride solution and
cool.
4.6 Transfer the contents to a separating funnel, draw off the aqueous acid layer into a second separating funnel, and shake it with three 50 ml portions of ethyl ether.
4.7 Dissolve the fatty acids in the ether used for washing
the aqueous liquid and extract with 10 ml portions of water until the extracts
are no longer acidic to methyl orange indicator.
4.8 Take out the ether layer in a beaker containing
anhydrous sodium sulfate.
4.9 Filter it through a No. 1 Whatman filter paper into a
tared beaker.
4.10 Distil off the ether slowly on a steam bath, and to the
residue, add 5 ml of acetone.
4.11 Warm the beaker in the steam bath at about 90 °C for 10
minutes. Allow to cool the baker and weigh.
4.12 Return the flask to the water bath for another 10
minutes, allow it to cool, and reweigh.
4.13 Repeat the process until the difference between two
consecutive weights is less than 0.005 g.
Liebermann-Burchard Test Procedure
Determination of fatty matter composition
4.14 Take 0.5 g fatty acid (* extracted from soap noodles
using the method as attached below) in a 100 ml conical flask, add 20 ml
methanol, and heat to dissolve.
4.14 Add 0.5 ml of thionyl chloride to it and warm it for 5
minutes. Then transfer it to a separating funnel of 125
Test Method Fatty Acids
4.15 Wash the conical flask with 20 ml of water and pour it into
the separating funnel. Now extract the fatty layer with 20 ml of petroleum
ether 60:80.
4.16 Wash the ether layer with water. Remove the water layer
and filter the ether layer through an anhydrous sodium sulfate bed on the Whatman
No. 40 filter paper.
4.17 Inject 1.0 microlitre of the filtered solution using
the above condition. From the resulting chromatogram, we can directly get the percentage
of different fatty acids present in the soap and soap noodles.
Determination of Free Fatty Acid and Iodine Value by Titration Method