ОПРЕДЕЛЕНИЕ СВОБОДНЫХ И ЭТЕРИФИЦИРОВАННЫХ ЖИРНЫХ КИСЛОТ В ПЛАЗМЕ КРОВИ МЕТОДОМ ГАЗОВОЙ ХРОМАТОГРАФИИ С МАСС-СЕЛЕКТИВНЫМ ДЕТЕКТИРОВАНИЕМ

A GC-MS method was developed for quantification of 32 free and esterified fatty acids: 12 saturated fatty acids (C 11 -C 24 ) and 20 unsaturated and polyunsaturated fatty acids (C 16 -C 24 ). GC-MS quantification was performed in two stages. At first, esterified fatty acids were converted to methyl esters by transesterification with KOH in MeOH. At the second stage free fatty acids were converted to methyl esters by extractive alkylation with methyl iodide in CH 2 Cl 2 and tetrabutylammonium hydroxide. Relative calibration was performed with deuterated palmitic acid and methyl palmitate as internal standards. Range of measured concentrations was 0.2 to 800 mkg/ml. Relative standard deviation was below 15%. The soft conditions for preparing the samples tested lead to the absence of or minor transesterification side reactions, oxidation and hydrolysis. It is proved that during the extraction procedure esterified fatty acid does not increase the concentration of free fatty acids, indicating the absence of conversion of esterified to free fatty acids. The technique was tested in the study of fatty acids of blood plasma of human volunteers. Key words : blood plasma, free fatty acids, esterified fatty acids, extractive alkylation, GC-MS (Russian) DOI:  http://dx.doi.org/10.15826/analitika.2015.19.2.002 T.I. Orlova, A.I. Ukolov, E.I. Savel’eva and A.S. Radilov Research Institute of Hygiene, Occupational Pathology and Human Ecology Federal State Unitary Enterprise, Federal Medical Biological Agency of Russia Kapitolovo Station, g/p Kuz’molovsky, Vsevolozhsky District, 188663 Leningrad Region, Russian Federation