Determination of selenomethionine by high-performance liquid chromatography-fluorescence detection coupled with on-line oxidation.

A simple and sensitive determination method for selenomethionine (Se-Met) using an HPLC-fluorescence detection system coupled with an on-line electrochemical reactor has been developed. NBD-F (4-fluoro-7-nitro-2,1,3-benzoxadiazole) was used as the fluorescent derivatization reagent for Se-Met. NBD-Se-Met was separated from NBD-derivatives of 22 other amino acids within 35 min. Applying an optimized oxidation potential enhanced the fluorescence intensity of NBD-Se-Met 10-fold. The calibration curve was linear in the range of 300 fmol to 30 pmol with a correlation coefficient of 0.997. Detection limit (S/N = 3) was calculated to be 50 fmol, which is comparable to that of inductively coupled plasma mass spectrometry. This simple and sensitive method should be useful for the determination of Se-Met in physiological samples, such as serum or urine.