Selenium Species Determination in Se-Enriched Grain Crops with Foliar Spray of Sodium Selenite by IP-RP-HPLC-UV-HG-AFS

A simple, rapid, and accurate method for determination of selenocystine (SeCys2), methyl selenocysteine (MeSeCys), selenourea (SeUr), selenite (Se(IV)), selenotmethionine (SeMet), and selenate (Se(VI)) in grain crops was developed, based on the coupling of ion-pair reversed-phase high-performance liquid chromatography (IP-RP-HPLC) and ultraviolet irradiation hydride generation atomic fluorescence spectrometry (UV-HG-AFS). The conditions of IP-RP-HPLC-UV-HG -AFS were studied. The conditions of the pretreatment sample, such as types and dosage of proteinases, were investigated. The detection limits (LODs) for six Se species were between 0.77 and 1.77 μg·L−1. Then, the proposed method has been successfully used to analyze selenium (Se) species in Se-enriched rice paddy (Oryza sativa L.), soybean (Glycine max (Linn.) Merr.), and sweet potato (Ipomoea batatas (L.) Lam.) with foliar application of sodium selenite solution. SeMet was the major Se spices in Se-enriched grain crops, ranged from 77–90% of the total Se contents. The capabilities of Se enrichment were relatively larger differences in three-grain corps as follows: soybean > rice paddy > sweet potato.