Mass Spectrometric Identification of Aliphatic Amines Using 2-(11H-benzo[a]carbazol-11-yl) Ethyl Chloroformate as Fluorescence Labeling Reagent

A simple and highly sensitive method based on the precolumn derivatization has been developed for the determination of aliphatic amines in food by using a nitrogen-containing 2-(11H-benzo[a]carbazol-11-yl)ethyl chloroformate (BCEC-Cl) as a fluorescence labeling reagent followed by high-performance liquid chromatography (HPLC) with fluorescence detection, and online postcolumn MS identification. The stable derivatives can be obtained by the labeling reaction of BCEC-Cl with amines in the presence of a borate buffer (pH 9.0) within 3 min. The maximum excitation and emission wavelengths are at λex = 279 nm and λem = 380 nm respectively. Separation of 12 amine-derivatives was achieved by a gradient elution on a reversed-phase Eclipse XDB C8 (150 mm × 4.6 mm, 5 μm) column with a good baseline resolution. The identification of amine-derivatives is carried out by online postcolumn MS using atmospheric pressure chemical ionization (APCI) as an ion source in positive-ion detection mode. The established method exhibits excellent reproducibility and recovery. Excellent linear responses are observed with coefficients > 0.9996, detection limits (at signal-to-noise ratio of 3:1) are at 1.77–14.4 f mol levels.