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

Six-carbon (C-6) 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 C-6 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 C-6 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 similar to 60 min with good recovery, linearity, and reproducibility, and with detection limits of 0.25 and 3.1 mu g/L, for hexanal and (E)-2-hexenal, respectively.