Enantiomeric Analysis of Flavor Compounds by Multiple Headspace Solid-Phase Microextraction Gas Chromatography-Mass Spectrometry

A quality assessment method for eight commercially available optically active flavor compounds: menthol, menthyl acetate, perillaldehyde, 1,8-cineole, α-pinene, limonene, neomenthol, and neomenthyl acetate, was developed for commercial foods. The simultaneous determination of the eight flavor compounds and the optical purity test for the complete enantiomeric separation of each flavor compound were achieved by gas chromatography-mass spectrometry (GC/MS) equipped with a tandem capillary column consisting of a fused silica column (DB-17MS) coupled with a cyclodextrin chiral column (β-DEX). The extraction of the flavor compounds from the food samples was carried out by a multiple headspace (MHS) solid-phase microextraction (SPME) technique in order to improve the quantitativeness of SPME. Optimization of MHS-SPME using a mathematical technique with repeated extraction yielded the total peak area of each flavor compound and excellent recoveries from the food samples in three repeated measurements. Of the twelve commercial samples subjected to the optical purity test, some were found to have undesirable enantiomers that are not designated as flavor compounds by the Food Hygiene Law of Japan. The results show the efficiency of the developed method, and suggest a need to conduct further optical purity tests for the quality assessment of flavor compounds in commercial foods.