Determination of free fatty acids in human serum by HPLC with fluorescence detection.

It has been suggested that serum concentrations of polyunsaturated essential fatty acids correlate with the symptoms or severity of various diseases, including depression and Alzheimer-type dementia, and that determination of serum fatty acids might be important for disease diagnosis. Thus, we developed to analyze serum fatty acids in healthy individuals by using a high-performance liquid chromatography method with fluorescence detection, because free fatty acids have a carboxyl group that can be derivatized with a fluorescent reagent, 4-N,N-dimethylaminosulfonyl-7-N-(2-aminoethyl)amino-2,1,3-benzoxadiazole. This approach could quantify five types of free fatty acids [α-linolenic acid (ALA), palmitoleic acid (PLA), arachidonic acid (AA), linoleic acid (LA) and oleic acid (OA)] in human serum. The detection limits of the method were in the range of 2.29-4.75 fmol (signal-to-noise ratio 3), and absolute concentrations of ALA, PLA, AA, LA and OA were 8.27 ± 1.04, 18.8 ± 2.95, 49.9 ± 4.03, 230 ± 18.1 and 201 ± 22.1 µM, respectively.