Molecular Weight Determination of Oils

Molecular Weight Determination of Oils

Molecular weight of oils is determined by the saponification number which is the amount of sodium or potassium hydroxide (in mg) required to saponify 1 gm of fat under specific conditions.

To find the saponification value of oil, firstly we have to treat the oil sample with an ethanolic solution of KOH (or any excess solution of alkali) using a reflux technique for about 30 mins. Gas Chromatography (GC) can also be used to calculate the SV value.  Gel permeation chromatography (GPC) and Mass Spectrometry (MS) can also be used to determine the molecular weight of oils.

GPC is a liquid chromatography technique that utilizes a column (or a series of columns) packed with a porous gel material to separate the polymers or other analytes based on hydrodynamic volume. We can obtain accuracy in molecular weight by appropriate use of ionization techniques and precise parameters.

Video 01: Molecular Weight Determination

Common Uses of determining Molecular Weight of Oil:

•  Oils with high saponification value are used in making soaps.
•   Ink, chemical paints, ball point pen etc.

Advantages of determining Molecular Weight of Oil:

• To determine viscosity of fluid.
• To determine surface tension of fluid.

Industrial Application of determining Molecular Weight of Oil:

•  Making cellulose plastic
• Producing petroleum products etc.