Abstract: Under the optimal extraction conditions, a method of ultrasound-assisted solvent extraction (USE) combined with gas chromatography-mass spectrometry (GC-MS) was established to determine volatile substances in polypropylene (PP) packaging materials for self-heating foods. The extraction efficiencies of n-hexane, ethanol, ethyl acetate and dichloromethane for the extraction of volatile substances from self-heating food packaging material were examined. The analytes were qualitatively identified by mass spectral deconvolution with the MS-DIAL software, NIST mass spectral library searching, and chromatographic retention indices. The Cramer class for each identified compound was determined by the threshold of toxicological concern to evaluate their safety, and relative odor activity values were calculated to identify potential odorants. The results showed the extraction efficiencies of n-hexane, ethyl acetate and dichloromethane were similar, and they all had higher extraction efficiency for hydrocarbons, while ethanol had higher extraction efficiency for esters. A total of 72 volatile components were detected in 3 samples, among which 12 components such as N-(2-ethylamino)-1,3-propanediamine, nonanal, 2,4-di-tert-butylphenol, butylated hydroxytoluene, and 2-bromotetradecane should be of more concern. In addition, 14 volatile odor substances were identified, among which nonanal, undecane and hexadecane could potentially contribute to the odor of self-heating food polypropylene packaging. This study provides a scientific method for the analysis of volatile components in self-heating food PP packaging, and provides data support for the safety assessment as well as odor analysis of self-heating food PP packaging.

Key words: ultrasound-assisted solvent extraction; gas chromatography-mass spectrometry; self-heating food; polypropylene; volatile components