Abstract:

A method for rapid separation and determination of four fatty acid monoglycerides, via ultra-performance convergence chromatography-mass spectrometry, was developed. Fatty acid monoglycerides were prepared by lipase-catalyzed glycerolysis using sunflower oil as the starting material. The main monoglycerides are monopalmitin, monostearin, monoolein, and monolinolein. The samples were dissolved by n-hexane/isopropanol(7:3 volume ratio), separated in 6 min on the column of ACQUITY UPC² BEH 2-EP(100 mm×2.1 mm, 1.7 μm) with gradient elution of carbon dioxide and methanol/acetonitrile(1:1 volume ratio) system, and then detected by MS detector in the ESI⁺ mode. The results verified that the standard curves for the four components were obtained with good correlation coefficients(R²)>0.9983 in their concentration ranges. The limits of detection(LOD, S/N=3) for the four monoglycerides are in the range of 0.036~0.093 mg/L. The recoveries for the four monoglycerides at three spiked levels(low, middle, high) are 88.50%~110.00% with the relative standard deviations of 1.01%~4.04%. The proposed UPC²-MS method is featured with low detection limit, less time consuming, good separation and low cost. It would provide a new chromatographic technology platform for the detection of fatty acid esters.

Key words: ultra-performance convergence chromatography-mass spectrometry(UPC2-MS), fatty acid monoglyceride, glycerolysis, sunflower oil