Determination of 21 phthalic acid esters in edible vegetable oils by gas chromatography-tandem mass spectrometry with removing fat through ultra low temperature freezing

A new method was developed for the determination of 21 Phthalic Acid Esters(PAEs)in edible vegetable oils by gas chromatography tandem mass spectrometry(GC-MS/MS)with removing fat through ultra low temperature freezing. With acetonitrile as extractant,sample was extracted and frozen with ultra low temperature at-80℃ for 10 min to remove fat,and then the sample solution was evaporated to near dryness by rotary evaporator and redissolved by n-hexane,and then detected by GC-MS/MS under multiple reaction monitoring modes. All analytes had good linearity with correlation coefficient over 0.999 in the investigated range(1~1000 ng/mL),the limits of detection(LOD)were 0.10~8.52 μg/kg,the limits of quantitation(LOQ)were 0.32~28.40 μg/kg,the recoveries were 74.31%~116.62% with the relative standard deviation ranged of 1.21%~17.82%. Seven categories of 19 kinds of vegetable oil were examined,the results indicated that dimethyl phthalate(DMP),diethyl phthalate(DEP),diisobutylphthalate(DIBP),di-n-butyl phthalate(DBP),butyl benzyl phthalate(BBP),bis(2-butoxyethyl)phthalate(DBEP),di-n-heptyl phthalate(DHP),bis(2-ethylhexyl)phthalate(DEHP)and di-n-octyl phthalate(DNOP)total of 9 PAEs were detected,including DMP,DBP,DBEP,DHP and DEHP detection rate of more than 90% with the content in the range of 105.57~2156.76 μg/kg. The method was easy to operate and low cost,which could be used for the effective determination of PAEs in edible vegetable oil.