Rapid Analysis of C6 Aldehydes by Solid-Phase Microextraction Sheets and Direct Analysis in Real-Time Mass Spectrometry (SPMESH-DART-MS)

Six-carbon (C₆) carbonyls formed from lipid oxidation (e.g., hexanal, (E)-2-hexenal) are routinely used as quality markers in the food industry. Typically, these carbonyls are measured by gas chromatography–mass spectrometry (GC-MS) or related approaches. Recent work demonstrates that parallel extraction of headspace volatiles using sorbent sheets (HS-SPMESH) followed by direct analysis in real-time mass spectrometry (DART-MS) can be used as a rapid alternative to GC-MS. However, SPMESH-DART-MS measurement of C₆ carbonyls is complicated by their low extractability onto polydimethylsiloxane-based SPMESH sheets and poor DART-MS ionization behavior. This work reports on the development and validation of a rapid HS-SPMESH-DART-MS approach to measurement of C₆ carbonyls following their in situ derivatization with O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine in multiple food matrices including grape juice, soy milk, conventional milk, and mayonnaise. Including derivatization and extraction time, the method can analyze 24 samples in ∼60 min with good recovery, linearity, and reproducibility, and with detection limits of 0.25 and 3.1 μg/L, for hexanal and (E)-2-hexenal, respectively.