Polyunsaturated Fatty Acids in Dried Milk Samples: Validation of a Lipid Separation-Free Method

A method to determine polyunsaturated fatty acids (linoleic and α-linolenic acids and its long chain metabolite, DHA) in milk samples, avoiding the fat separation step, was developed and validated. The transesterification reaction was carried out directly on freeze-dried milk samples to produce fatty acid methyl esters. Separation, identification and quantification of analytes were performed by GC–MS. In these experimental conditions the matrix effect was negligible. Values for repeatability and intermediate precision demonstrate excellent method precision. To test the method applicability, goat’s, cow’s and human’s milk with different fat contents and essential fatty acids concentrations were examined.