Simultaneous Determination of Maltol, Ethyl Maltol, Vanillin, and Ethyl Vanillin in Foods by Isotope Dilution Headspace Solid-Phase Microextraction Coupled with Gas Chromatography-Mass Spectrometry

Maltol, ethyl maltol, vanillin, and ethyl vanillin are food additives frequently used as flavor enhancers or stabilizers in food. In order to investigate their uses in various foods, to evaluate their potential health risk, or to distinguish fraudulently mislabeled food, a reliable analytical method is essential to obtain accurate concentrations of these additives in a variety of food samples. In the present study, a method based on isotope dilution headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry was developed for the simultaneous determination of the four flavor compounds. Optimal values of relevant parameters affecting extraction efficiency and detection sensitivity were determined and then applied to the analysis of real samples. Using the determined optimal conditions, the limits of detection of the method were determined as 0.005–0.50 μg/g for milk tea and infant formula milk powder and as 0.01–0.05 μg/g for blended sesame oil. Using the proposed method, high contents of ethyl maltol and vanillin, up to 833 ± 15 μg/g and 1044 ± 20 μg/g, respectively, were detected in milk tea. Additionally, maltol, ethyl maltol, and vanillin over a range of 0.286–1.65 μg/g were detected in blended sesame oil. By contrast, the four flavor compounds were not detected in infant formula milk powder samples. With the advantages of good reliability and the capacity for simultaneous detection, the present method can be applied to detect adulteration and evaluate any health risks in a range of foods by the four flavor compounds.