Study of the evolution of 3-MCPDEs and GEs in the infant formula production chain employing a modified indirect method based on magnetic solid phase extraction

Herein, a modified indirect method was established for the determination of 3-monochloropropane-1,2-diol esters (3-MCPDEs) and glycidyl esters (GEs), employing magnetic solid phase extraction by boronic acid-functionalized magnetic nanoparticles to replace the traditional clean-up procedure. Compared with routine methods, it has been proved to be more sensitive with limits of detection in the range of 0.02–1.5 μg/kg and less susceptible to contamination of phenylboronic acid derivatives and fatty acid methyl esters. The proposed method was applied to analyze 42 samples covering the entire infant formula (IF) production chain. Results revealed that homogenization process contributed 79–91 % of the total growth of the contaminants due to the vegetable oil addition, while the following evaporation and spray-drying processes contributed 9–21 % of the total growth owing to involved heat treatment. The GE levels in final IF products exceeded the maximum level set by EU regulation 2020/1322, indicating quality safety concerns in the production chain.