title: Characterization of selenium species in Brazil nuts by HPLC-ICP-MS and ES-MS.
abstract: Brazil nuts have been classified as the foodstuffs that contain the highest level of unadulterated selenium, an essential trace element that appears to prevent cancer. To date, characterization of the selenium species in brazil nuts has not yet been investigated. In this work, various sample preparation approaches, including microwave extractions and enzymatic treatments, are examined with the goal of species preservation and subsequent selenium speciation; of these approaches, an enzymatic treatment with Proteinase K proved most effective. High-performance liquid chromatography (HPLC) separation strategies and inductively coupled plasma mass spectrometry (ICP-MS) detection schemes will also be presented. Extracts are evaluated against available standards for the commercially obtainable seleno-amino acids, selenomethionine (SeMet), selenoethionine (SeEt), and selenocystine (SeCys); selenomethionine was demonstrated to be the most abundant of these seleno-amino acids. Further characterization of unidentified selenium-containing peaks is attempted by the employment of several procedures, including electrospray-mass spectrometry (ES-MS). A peptide structure was identified; however, this was considered a tentative proposal due to the large background produced by the extremely complicated brazil nut matrix.
authors.affiliation: Department of Chemistry, University of Cincinnati, Ohio 45221-0172, USA.
authors.forename: Anne P
authors.initials: AP
authors.lastname: Vonderheide
authors.forename: Kazimierz
authors.initials: K
authors.lastname: Wrobel
authors.forename: Sasi S
authors.initials: SS
authors.lastname: Kannamkumarath
authors.forename: Clayton
authors.initials: C
authors.lastname: B'Hymer
authors.forename: Maria
authors.initials: M
authors.lastname: Montes-Bayón
authors.forename: Claudia
authors.initials: C
authors.lastname: Ponce De León
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Caruso
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003553:Cystine / Q000031:analogs & derivatives* / Q000032:analysis; D019684:Magnoliopsida / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods*; D008872:Microwaves; D017942:Nitric Acid / Q000032:analysis; D016566:Organoselenium Compounds / Q000032:analysis*; D012643:Selenium / Q000032:analysis*; D012645:Selenomethionine / Q000032:analysis; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D016566:Organoselenium Compounds; C009226:selenocystine; D017942:Nitric Acid; D003553:Cystine; D012645:Selenomethionine; D012643:Selenium