Method as described in the national food safety standard GB 5413.27-2010 “Determination of fatty acids in foods and dairy products for infants and young children” was referred to by our laboratory, to determine the content of 6 types of fatty acids in milk powder.  These fatty acids are lauric acid, myristic acid, γ-linolenic acid, α-linolenic acid, erucic acid and arachidonic acid (ARA).
In the experiment, the fat in the milk powder was extracted with organic solvent, then the extracted fat was saponified to form free fatty acid, and lastly, the methyl esterification reaction was carried out under the catalysis of boron trifluoride.  Those fatty acid methyl ester formed were analyzed by a Gas Chromatograph equipped with a hydrogen flame ionization detector (FID) and quantified by external standard method.
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