A MODIFICATION OF GAS CHROMATOGRAPHY METHOD FOR THE DETERMINATION OF FATTY ACID COMPOSITION OF MILK FAT

P. Mechkarova, G. Kalinova, H. Daskalov, D. Mladenova

Abstract: Gas chromatography method, described in ISO 15885, was modified using a certified reference material (CRM), different from that specified in the method, capillary column with selective polar phase and preparation of methyl esters was carried out with other esterifying reagents. The applicability of the modified method for determination of fatty acid composition was studied via evaluation of some important characteristics: selectivity, linearity and linear range, accuracy, precision and measurement uncertainty of the method. The selectivity and linearity of the method were investigated with CRM 47885 – Supelco 37 Component FAME Mix. Due to the column efficiency, the results for selectivity of four fold greater concentration were better than required in ISO 15885. The linearity range for 37 fatty acids was (22.03 ÷ 399.7) μg.ml-1. To determine the accuracy of the modified method we analyzed milk fat of an interlaboratory test. The results met the range 90% ÷ 110% and there was no need for recovery. To evaluate the precision of the method five dairy products were analyzed. The obtained results were significantly better than required in ISO 15885, as the method for esterification of fatty acids was simplified and easy to perform. The uncertainties for the quantities of saturated and unsaturated fatty acids of five dairy products were low, as a result of relatively small deviations in measured precision.

Keywords: determination of fatty acid composition of milk fat; FAMEs; gas chromatography

Date published: 2017-08-31