CHED 249

Presented here is the comprehensive speciation of organic (selenomethionine, selenocystine, seleno-(methyl)-Se-cysteine) and inorganic (selenate (SeIV), selenite (SeVI) selenium species in an ethanolic extract of garlic via liquid chromatography-particle beam/electron impact mass spectrometry (LC-PB/EIMS). An evaluation of the source temperature was performed for the EI source at the standard electron energy of 70 eV. The EI process yields mass spectra, which reflect clear and simple fragmentation patterns of the chemical species eluting from the chromatographic column. Analytical response characteristics were obtained for each of the selenium species and limits of detection in the single nanogram level were achieved. The separation of the selenium species was accomplished by reversed phase liquid chromatography and a gradient elution system of water containing 0.1% TFA and methanol.