Isopropyl-naphthylamide-hydrazine as a novel fluorescent reagent for ultrasensitive determination of carbonyl species on UPLC

Reactive carbonyl species (RCS) are ubiquitous compounds existing in organisms and environment, while the current methods no longer suitable for analysis of instable and violate RCS due to their harsh reaction condition and multistep pretreatment. In this work, a simple, rapid and ultrasensitive UHPLC-FLD method has been established by employing the 1,8-naphthylamide as fluorophore and the hydrazine as carbonyl recognition unit (named NH) to fluorescent derivatization. The synthesized NH performs expectant 300-fold “off–on” signal with high reactivity to carbonyl species and transition state calculation under density functional theory (DFT-TS) has revealed the activation energy of 18.81 kcal·mol−1 indicating the NH can interact with carbonyls at room temperature. By using the NH as a novel fluorescent reagent, the optimized UHPLC method shows satisfactory precision (RSD ≤ 1.5%) and ultralow LODs (1.0 × 10−12 M) and good linearity (R2 ≥ 0.999) for 10 carbonyls within only 8 min. The established method has been successfully applied to analysis RCS in air and organisms, especially, with assistance of manual packing SPE cartridge, the pretreatment of air sampling can be greatly simplified. It is believed that the proposed methodology can become to an effective procedure for developing novel UHPLC-FLD methodology for other analytes.