HPLC-MS/MS method for the simultaneous determination of lysine-derived markers for protein carbonylation in meat

This paper aimed to develop a quantitative method based on high-performance liquid chromatography (HPLC) coupled with triple quadrupole tandem mass spectrometry (MS/MS) for the simultaneous determination of two protein carbonylation products derived from lysine residues in meat proteins, namely, α-aminoadipic semialdehyde (AAS) and lysinonorleucine (LNL). Mass spectrometry conditions and derivatization parameters were optimized and the linearity, repeatability, bias, the limit of detection (LOD), the lower limit of quantification (LLOQ), and recovery were validated. The developed method showed satisfactory linearity, repeatability, and sensitivity for both AAS and LNL. This method was applied to analyze the contents of these compounds in different meat products, and the formation of AAS was observed to be closely related to the severity of the manufacturing conditions. Moreover, AAS was demonstrated to be a reliable but more sensitive marker for protein carbonylation compared to the DNPH method, which could also provide information regarding the specific pathway of protein carbonylation.