Dual-Sensitive Probe of 2-(Benzoacridin)ethyl-imidazole-1-carboxylate for Determination of Aliphatic Amine with Fluorescence and Online Atmospheric Pressure Chemical Ionization Mass Spectrometry Identification

Using three different derivatization methods to mark the amine compounds, we compared the difference of derivatization efficiency and gave the optimal method. 5-(2-Hydroxyethyl)benzoacridine reacts with coupling agent N,N′-carbonyldiimidazole (CDI) to form an activated amide intermediate 2-(benzoacridin)ethyl-imidazole-1-carboxylate (BAEIC). BAEIC, which is dual-sensitive probe, reacts preferably with amino compounds at 80 °C in the presence of 4-dimethylaminopyridine (DMAP) catalyst in N,N-dimethylformamide (DMF) solvent to give the corresponding sensitively fluorescent derivatives with an excitation maximum at 280 nm of λex and an emission maximum at 510 nm of λem. BAEIC-amine derivatives simultaneously exhibited high-ionization potential with percent ionization δ changing from 5.62% to 58.08% in aqueous acetonitrile and from 2.14% to 56.58% in aqueous methanol. Derivatives are not only sensitive to fluorescence but also to MS ionizable potential. The fluorescence detection limits are 0.12–0.59 ng mL−1 (at a signal-to-noise ratio of 3). The online Atmospheric Pressure Chemical Ionization Mass Spectrometry (APCI-MS) detection limits are 1.89–14.12 ng mL−1 (at a signal-to-noise ratio of 5).