Rapid Determination of Mono-, Di- and Tri-isopropyl Citrate in Foods by Gas Chromatography

A simple and rapid method for determining mono-, di- and tri-isopropyl citrates in foods was developed. Isopropyl citrates in butter and milk powder were extracted with ethyl acetate under acid condition and in edible oil with hexane. The ethyl acetate containing isopropyl citrates was evaporated and the residue was taken up in hexane. The isopropyl citrates in hexane were extracted into acetonitrile. After evaporation of the solvent, isopropyl citrates were methylated with diazomethane, and they were determined by gas chromatography. Recoveries of mono-, di- and tri-isopropyl citrates from edible oil, butter and milk powder by this method were more than 92.9%, 95.7% and 94.8%, respectively. The detection limits of isopropyl citrates were 1 μg/g of sample.