<i>N</i>-Heterocyclic Carbenes: Novel Derivatization Reagents for LC-MS Analysis of Aliphatic Aldehydes

<i>N</i>-heterocyclic carbenes (NHCs) are versatile catalysts for organic reactions, characterized by their unique electron-donating properties and high activity. This study introduces NHCs as innovative derivatization reagents for liquid chromatography-mass spectrometry (LC-MS) analysis of aliphatic aldehydes. Five distinct NHC reagents were evaluated, and 2-mesityl-2,5,6,7-tetrahydropyrrolo[2,1-<i>c</i>][1,2,4]triazol-4-ium chloride (MTPTC) was identified as the most promising candidate due to its rapid reaction kinetics, high selectivity, and excellent product stability. The MTPTC-based derivatization reaction effectively addressed the issue of stereoisomeric products, resulting in well-resolved single peaks in the LC separation. Additionally, the derivatized products exhibited high stability, facilitating accurate and reliable quantitative analysis. Using MTPTC as the derivatization reagent, an LC-MS quantitative analysis strategy was developed for the determination of eight aliphatic aldehydes in human sera. The method demonstrated a broad linear range, low limits of detection and quantification, and satisfactory reproducibility and accuracy. The applicability of this method was further validated through the quantification of aliphatic aldehydes in the serum of sepsis patients. This work extends NHCs' utility to analytical chemistry and introduces a novel derivatization reagent for the analysis of carbonyl compounds by LC-MS.