Abstract: A gas chromatography-mass spectrometry (GC-MS) method for the detection of 3-chloropropyl alcohol ester, 2-chloropropyl alcohol ester and glycidyl esters in oils and milk powder was established and applied for the detection of ester pollutants in vegetable oils and infant formula powder. Meanwhile, the differences in the pollution levels of three harmful esters in different vegetable oils were analyzed, and the correlation with the fat content of milk powder was studied. Among the vegetable oils commonly used in infant formula ingredients, palm oil had the highest pollution level, followed by rapeseed oil, soybean oil, corn oil and edible vegetable oil blend, and sunflower seed oil, coconut oil, walnut oil, flax seed oil had lower pollution levels. The pollution levels of 1,3-dioleic acid-2-triglyceride palmitate (OPO) and edible vegetable oil blend (containing OPO) were the lowest. Totally 88.4% of the 95 infant formula powder samples were found to contain 3-monochloropropane-1,2-diol ester (3-MCPDE) at concentrations of ND?0.231 mg/kg, with an average of 0.070 4 mg/kg and a median value of 0.064 5 mg/kg. 2-MCPDE was detected in 42.1% of the samples at concentrations of ND?0.034 mg/kg. The detection rate of GE was 2.1% at concentrations of ND?0.019 mg/kg. The 3-MCPDE content in 10.5% of the samples exceeded the EU limit of 0.125 mg/kg. There was a significantly positive correlation between the total amount of the three ester pollutants and the fat content in milk powder, with a Pearson correlation coefficient of 0.453. In order to protect the safety of infants, infant formula manufacturers should carefully select raw oils and reduce the pollution of harmful esters in infant formula powder as much as possible under the premise of ensuring nutritional health.

Key words: infant formula powder; ingredient oil; chloropropyl alcohol ester; glycidyl ester; pollution analysis; differences