Chromatography Forum

Greet,
Can anybody give me a briefly explanation for Castor Oil Analysis?
Starting from the sample preparation until the GC parameter (including column, and temperature)

Thank you

Castor oil is a mixture of triglycerides, composed of c18 unsaturated fatty acids, mostly ricinoleic and oieic acids.

The fatty acid composition is determined by saponification of the triglycerides into their free acids which are derivatized as methyl esters/and or TMS ethers for separation by GC.

best wishes,

Rod

Analysis of high boilers is usually done on "HT" type phases. For example Rxi-5HT goes to 400C. Fused silica becomes brittle if used longer time above 350, so there is also the possibility to choose a metal column type, MXT, which will keep it's strength. There are specific MXT biodiesel columns that can be used up to 430C, which are also used for triglycerides

If you want separation of triglycerides acc. to degree of unsaturization, you can also use a Rtx-65TG phase. This polar phase is stable upto 370 and gives separatiions within carbon numbers.

Jaap de zeeuw, Restek corporation

Castor oil analysis can be done by the saponification/esterification described above. What makes castor different is the ricinoleic acid, or hydroxy-oleic acid. If you separate out the fatty acids, you can make TMS erivatives as detailed above, and the ricinoleic acid will have 2 TMS.

If you want to look at intact, I've used high-temperature GC and HPLC-ELSD.

One can also do reversed phase TLC and normal phase TLC to look at impurities which may not be seen by GC.

rod