title: A simplified method for inorganic selenium and selenoaminoacids speciation based on HPLC-TR-HG-AFS.
abstract: A simplified speciation method for the determination of selenite, selenate and three selenoaminoacids (selenocystine, selenomethylselenocysteine and selenomethionine) has being developed, based on the coupling of high performance liquid chromatography (HPLC), thermoreduction (TR), hydride generation (HG) and atomic fluorescence spectrometry (AFS). Most of the existing methods based on AFS detection employ a two step procedure to reduce selenate to selenite before HG: (i) Ultraviolet radiation followed by (ii) heating, to produce volatile hydrides of the selenium compounds. The proposed simplified method HPLC-TR-HG-AFS does not require ultraviolet radiation. Instead, KBr dissolved in a HCl solution is added during the heating step (thermoreduction), resulting in an effective hydride generation of the selenium species. Different variables (temperature, HCl and NaBH4 concentrations) have been optimized, using both univariant and multivariant experimental designs. The proposed method is therefore less complex and allows limits of detection, reproducibility and repeatability values similar or better than the existing AFS detection methods described in the literature. A Certified Reference Material (SELM-1 with certified selenomethionine content) and a Se-enriched algae sample have been successfully analyzed with the proposed method. The results were also compared to an alternative technique (GC-MS) that provided similar results.
authors.affiliation: Departamento de Química y Ciencia de Materiales, Campus El Carmen, Universidad de Huelva, Huelva 21007, Spain. rodas@uhu.es
authors.forename: Daniel
authors.initials: D
authors.lastname: Sanchez-Rodas
authors.forename: Fernanda
authors.initials: F
authors.lastname: Mellano
authors.forename: Emilio
authors.initials: E
authors.lastname: Morales
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Giraldez
mesh_terms: D001965:Bromides / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D003553:Cystine / Q000031:analogs & derivatives* / Q000032:analysis; D006358:Hot Temperature; D057230:Limit of Detection; D016566:Organoselenium Compounds / Q000032:analysis*; D010084:Oxidation-Reduction; D017680:Potassium Compounds / Q000737:chemistry; D015203:Reproducibility of Results; D064586:Selenic Acid; D018036:Selenium Compounds / Q000032:analysis*; D017279:Selenocysteine / Q000031:analogs & derivatives* / Q000032:analysis; D012645:Selenomethionine / Q000032:analysis*; D018038:Sodium Selenite / Q000032:analysis*; D012996:Solutions; D013050:Spectrometry, Fluorescence; D013054:Spectrophotometry, Atomic
chemical_list: D001965:Bromides; D016566:Organoselenium Compounds; D017680:Potassium Compounds; D018036:Selenium Compounds; D012996:Solutions; D017279:Selenocysteine; C009226:selenocystine; D003553:Cystine; D012645:Selenomethionine; D018038:Sodium Selenite; D064586:Selenic Acid; C039004:potassium bromide; C002979:selenomethylselenocysteine