Study On The Detection Method Of Glycidyl Fatty Acid Ester In Edible Oils

As kinds of minor food contaminant in edible oils, a reliable methodology for the quantification of glycidyl fatty acid esters is essential for understanding the mechanism of formation of them and for developing effective mitigation strategies.In this paper, two novel methods to quantify glycidyl fatty acid esters (GEs) had been developed. One of them was in combination with derivatization and UV. The GEs were derivatized with N,N-diethyldithiocarbamate sodium (DTC), then orthophosphoric acid was used to terminate reaction, and the resultants were detected by UV at278nm. Experiments on the temperature, time, phosphoric acid added amount and other conditions of derivatization reaction were optimized to get the best reaction conditions, which were as follows:GEs and N, N-diethyldithiocarbamate sodium molar ratio:1:100, phosphate buffer adjusted pH=7, heated for30min at70℃, the reaction was stopped by adding2.5mL85%phosphoric acid. The method provided a limit of quantification of1-50μg/mL for the standard stearic glycidyl fatty acid esters (GE-S), which enabled the detection of standard glycidyl fatty acid esters in0.5μg/mL, relatively. When the method was used to quantify GEs in nine commercial sources of edible oils, the results ranged from8.2-46.4μg/g, and a relative standard deviation was1.2-8.5%.A high temperature gas chromatography method was also developed for detecting the content and kind of glycidyl fatty acid esters in edible oil samples.Using Gel permeation chromatography(GPC) to.separate glycidyl esters from the triglyceride, diglyceride and monoglyceride in the oils, then detected by gas chromatography without derivatization. Experiments on the inlet pressure, split ratio, temperature program and other conditions of GC detection were optimized to get the best reaction conditions, which were as follows: DB-5HT Capillary column, inlet pressure was23pound per square inch, split ratio:10:1, the injection port and detector temperature are both360℃, oven temperature kept80℃for1min, rose to280℃by10℃/min, then rose to340℃by5℃/min and kept for27min. Retention time was15.702min. The calibration curves of GE-S showed a good linear correlation at concentration range of1-50μg/mL. The method was enabled the detection of standard glycidyl stearate in0.5μg/mL. When the method was used to quantify GEs in nine commercial sources of edible oils, the result ranged from6.6-43.2μg/g, and a relative standard deviation was2.6-22.7%. These two methods mentioned above can be used in rapid detection of glycidyl fatty acid esters.