Direct method for quantification of glycidol fatty acid esters in edible oils



In response to great concerns about glycidol fatty acid esters (GEs), trace contaminants in edible oils which possibly form during refining processes, we previously developed direct methods to quantify GEs using a combination of double SPE and HPLC-MS. In this study, those quantitative methods were improved to be more rapid without the use of harmful chloroform. To improve the speed, the HPLC-MS measuring time was reduced from 15 to 5 min by using a step gradient HPLC system, and the evaporation time after the first SPE was shortened from 4 to 1.5 h by changing the solvent used from acetonitrile to methanol. To replace chloroform with other solvents, we adopted tert-butyl methyl ether/ethyl acetate to dissolve the oils and n-hexane/ethyl acetate to separate them during the second SPE. The limit of quantification for GE-in-oil was 0.082–0.11 µg/g, which is the most sensitive of all existing methods. The recovery values of spiked GEs at concentrations of 1 or 10 µg/g were close to 100%. The levels quantified using an internal standard C17:0-GE were comparable with those using external standards in four different edible oils tested. This rapid method not using chloroform can be useful as a routine method to quantify GEs in oils.