High-sensitivity quantification of trace carbonyl compounds in wine by a derivatization-free SPE-SBSE-TD-GC-GC-MS...

Trace carbonyl compounds play a critical role in wine aroma due to their extremely low sensory thresholds. The analytical challenge arises from the structural diversity of these compounds, which span a broad range of volatility and polarity, as well as from their occurrence at trace levels in a complex matrix. Current approaches frequently rely on derivatization to achieve adequate sensitivity and stability. In this work, a high-sensitivity, derivatization-free analytical strategy is proposed for the quantification of ketones, alkanals, alkenals, and alkadienals in wine, based on a dual preconcentration approach combining solid phase extraction (SPE) and stir bar sorptive extraction (SBSE), followed by thermal desorption and heart-cutting comprehensive gas chromatography coupled to mass spectrometry (TD-GC-(FID)-GC-MS). Key parameters affecting extraction efficiency and chromatographic performance were systematically optimized, including SPE breakthrough volume, elution conditions, SBSE dilution factor, ionic strength, analyte load, and extraction time. The implementation of heart-cutting GC provided enhanced chromatographic resolution and selectivity for these carbonyls, while reducing interferences and instrumental noise, thereby improving overall sensitivity. The validated method demonstrated good linearity, repeatability (<10%), and reproducibility (<13%), with detection limits below reported sensory thresholds. The method was successfully applied to 63 young red wine samples, enabling the quantification of trace carbonyls across a wide concentration range. By eliminating derivatization while achieving high sensitivity and robust performance in a complex matrix, the proposed methodology represents a significant analytical advancement for the determination of trace carbonyl compounds in wine.