Acylglycerols analysis

ANALYSIS 

OF

ACYLGLYCEROLS

Acylglycerols (or glycerides) are formed of mono-, di- and triacylglycerol classes.
In tissue extracts the bulk of glycerides is in fact mainly formed by triacylglycerols with traces of the other classes. This is the case for blood or plasma where only triacylglycerols are found.  If present in sufficient amounts, the estimation of mono-, di- and triglycerides can be made after their separation by TLC or column chromatography (review in : De Clercq N et al., Lipid Technol 2008, 20, 232). 
In general, the estimation of total glycerides or their classes is made by the estimation of glycerol and this is quoted as “triacylglycerol” content.

Determination of glycerol in acylglycerols

A very simple but non-specific method which is also useful for all lipid classes may be used for a first approximation of the lipid content in crude or purified extracts or for the estimation of lipid fractions separated by TLC. 
This method is based on charring of lipids in hot concentrated sulfuric acid.

Charring method for determination of lipids

When a precise study of one of the acylglycerol classes is needed, it becomes evident that each class must be separated from the neutral lipid fraction previously purified by silicic acid column chromatography. C. If large amounts of acylglycerols are needed (several grams) , they can be separated preparatively by column chromatography with silicic acid or Florisil as adsorbents. The elution is done with a stepwise sequence with hexane containing increasing proportions of diethyl ether. Most frequently, the separation is readily made by preparative or analytical TLC since only some mg of each lipid are needed for their complete analysis and quantification.

Thin-layer chromatography of acylglycerols

Each of the acylglycol classes can be the subject of various analyses such as fatty acid characterization or separation into molecular species differing in fatty acid chain length and degree of unsaturation.