DFT-guided magnetic molecularly imprinted polymers for rapid and selective enrichment of diethyl acetals in Baijiu

Aging contributes to the mellow flavor of light-aroma Baijiu partly by converting pungent aldehydes into softer-smelling acetals. Their trace levels, structural similarity, and matrix interference hinder quantification and marker identification. A DFT-guided MMIPs-AG-based MSPE-GC–MS method selectively determined four acetals, achieving >90% of equilibrium adsorption within 1 min in kinetic experiments, desorption in 10 min, enrichment factors of 22.9–38.9, detection limits of 9.4–19.0 μg/L, and recoveries of 82.8–110.6%. Analysis of nine light-aroma Baijiu samples across aging periods revealed patterns. Among them, isovaleraldehyde diethyl acetal (iVDA), hexanal diethyl acetal (HxDA), and 1,1,3,3-tetraethoxypropane (TEP) increased overall with aging, with concentrations ranging from 0.39 to 4.84 mg/L; however, phenylacetaldehyde diethyl acetal (PADA) increased from 2.37 to 4.28 before declining to 1.64 mg/L. These preliminary trends, despite one sample per labeled production year, provide an exploratory link between HxDA/TEP and labeled production year, guiding future controlled longitudinal and accelerated aging validation.