Comprehensive profiling of baijiu volatile compounds by fast polarity switching GC-IMS with direct injection.

Comprehensive characterization of volatile compounds is essential for understanding baijiu flavor and quality. However, conventional gas chromatography-ion mobility spectrometry (GC-IMS) methods are limited by single-polarity detection and headspace sampling. In this study, we developed a GC-Fourier deconvolution IMS (GC-FDIMS) method combined with fast polarity switching and direct injection. This method effectively overcomes the information loss associated with single-polarity detection and significantly improves the detectability of low-volatility compounds. A total of 105 volatile compounds were identified from two baijiu samples, sauce-aroma and strong-aroma, more than twice the number obtained by headspace GC-IMS. Detection sensitivity improved markedly for medium- and high-boiling compounds, including ethyl esters, pyrazines, lactones, and phenolics that critically impact flavor depth and aftertaste. This method provides robust chemical evidence for aroma type differentiation and demonstrates strong potential for flavor identification and quality authentication, establishing GC-FDIMS as a powerful high-throughput tool for distilled spirits analysis.