Simultaneous determination of typical toxic aldehydes formed during food frying and digestion using isotope dilution UHPLC-QqQ-MS/MS

An isotope dilution ultra-performance liquid chromatography–triple quadrupole mass spectrometry method was developed to simultaneously detect two typical kinds of α,β-unsaturated aldehydes, namely 4-hydroxy-2-hexenal (4-HHE) and 4-hydroxy-2-nonenal (4-HNE), in foods. The proposed method exhibited a linear range of 10–1000 ng/mL with a limit of detection of 0.1–2.0 ng/g and a limit of quantification of 0.3–5.0 ng/g. The recovery rates of these typical toxic aldehydes (i.e., 4-HHE, 4-HNE) and their d₃-labeled analogues were 91.54%–105.12% with a low matrix effect. Furthermore, this proposed method was successfully applied to a real frying system and a simulated digestion system, wherein the contents of 4-HHE and 4-HNE were determined for both. Overall, the obtained results provide strong support for further research into the production of 4-HHE and 4-HNE resulting from foods during oil digestion and frying.