Application Note 20733
A GC-FID Method for the Comparison of
Acid- and Base-Catalyzed Derivatization of
Fatty Acids to FAMEs in Three Edible Oils
Anila I. Khan, Thermo Fisher Scientific, Runcorn, UK
Introduction
Gas chromatography is the preferred analytical method
for the determination of fatty acid methyl esters (FAMEs).
The fatty acid content of food was analyzed after
derivatization to their methyl ester products. This
conversion involved either an acid or base esterification
process.
In this application, separation of a mixture of 37 FAMEs
in a reference standard was achieved on a TRACE
TR-FAME 100 m × 0.25 mm × 0.2 µm GC column.
The reference standard contained a wide range of carbon
chain lengths (C4–C24), with concentrations between
2–6% wt/wt. The high polarity phase GC column is
optimized for separating complex mixtures of
cis
- and
trans
-fatty acids.
The base esterification method [1] was used to derivatize
the fatty acid content in three fat matrices (palm oil,
margarine, butter) and this was compared with acid
catalyzed esterification [2] under equivalent conditions.
The FAME components in the three fat matrices were
then identified using the retention times established using
a 37 component reference standard.
BF
3
-methanol is one of the fastest and most convenient
ways to convert fatty acids to their methyl ester
derivatives. The reagent is supplied in an easy-to-use,
septum-sealed Hypo vial and offers convenient syringe
removal of the reagent without exposing it to air. Use of
the BF
3
-methanol reagent results in improved detection of
fatty acids in a fatty food matrix while maintaining good
chromatographic peak shape.
Key Words
TR-FAME, fatty acid methyl esters (FAMEs), BF
3
-methanol, derivatization,
cis-
and
trans
-fatty acid
Abstract
This application note demonstrates the analysis of 37 fatty acid methyl
esters (FAMEs) separated by a highly polar phased Thermo Scientific™
TRACE™ TR-FAME GC column. Results from two derivatization methods
(acid and base esterification) were compared for their efficiency in
converting fatty acids to their methyl esters on three different fat matrices
prior to GC analysis.
