Selenium species in leaves of chicory, dandelion, lamb’s lettuce and parsley

Lamb’s lettuce, dandelion, parsley and four cultivars of chicory were cultivated aeroponically for 41 days with nutrient solution containing 7 mg Se/L in the form of Na2SeO4. Se compounds were determined by high performance liquid chromatography–ultraviolet treatment–hydride generation atomic fluorescence spectrometry (HPLC–UV–HG-AFS) in the green parts of the selected plants. Se species were extracted by water and by enzymatic hydrolysis with Protease XIV. Separation of SeIV, SeVI, SeMet, SeMeSeCys and SeCys2 was made by a combination of anion and cation exchange chromatography in which the columns were connected on-line to a UV–HG-AFS detection system. Se accumulated efficiently in plant leaves up to 480 μg/g dry mass, mostly as SeVI, i.e. the form of Se in the nutrient solution. Beside inorganic Se, selenomethionine (6–21%), selenomethylselenocysteine (0.5–4.4%) and selenocistine (<DL-0.8%) were determined in the extracts after enzymatic hydrolysis. Some unidentified peaks were also observed in the chromatograms.