Zhao Xianen

Determination of Free Fatty Acids by High Performance Liquid Chromatography with Fluorescence Detection and Identification with Mass Spectrometry

Abstract On a reversed-phase Eclipse XDB-C8 column, 20 fatty acids were derivatized using 2-(2-(anthracen-10-yl)-1H-naphtho [2,3-d]imidazol-1-yl) ethyl-p-toluenesulfonate (ANITS) as the pre-column derivatization reagent and were separated by high performance liquid chromatography (HPLC) in conjunction with a gradient elution with fluorescence detection and mass spectrometric identification. The reagent was reacted with fatty acids in the presence of K2CO3 catalyst at 90°C min in N,N-dimethylformamide solvent. The fluorescence excitation and emission wavelength of the derivatives were λex = 250 nm and λem = 512 nm, respectively. The identification of fatty acid derivatives was performed by online MS/APCI (atmospheric pressure chemical ionization source) in positive model detection. All linear correlation coefficients for fatty acid derivatives are over 0.9999, and the detection limits, at a signal-to-noise rate of 3:1, are 24.8-98.8 fmol for labeled fatty acids. The established method is sensitive and reproducible for the determination of free fatty acids from real samples with satisfactory results.

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

Abstract 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-(11 H -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 λ ex = 279 nm and λ em = 380 nm respectively. Separation of 12 amine-derivatives was achieved by a gradient elution on a reversed-phase Eclipse XDB C 8 (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.