Identification of selenium species in selenium-enriched Lens esculenta plants by using two-dimensional liquid chromatography-inductively coupled plasma mass spectrometry and [77Se]selenomethionine selenium oxide spikes

Selenium speciation in Se-enriched Lens esculenta grown in hydroponic culture containing inorganic selenium as Na2SeO3 and Na2SeO4 was performed. After 16 days of growth, the plants were collected and divided in two parts, roots and stems and then analysed to identify and quantify selenium species. Speciation studies of the enzymatic extracts were carried out by using anion-exchange (PRP–X100) and size-exclusion/ion-exchange (Shodex Asahipak) columns coupled to inductively coupled plasma mass spectrometry (ICP-MS). The need of using two independent chromatographic mechanisms for unambiguous species identification is demonstrated. Moreover, the use of a [77Se]selenomethionine selenium oxide spike turned out to be critical to discriminate between selenium selenomethioine selenium oxide and selenocysteine.