title: Improved molecular fluorescence method for the determination of selenium in biological samples.
abstract: A procedure for the determination of selenium in whole blood and urine has been improved by optimization of the digestion and derivatization procedures. An overnight pre-digestion step with 4 + 1 concentrated nitric-perchloric acids reduced the time of mineralization at 170 degrees C from 4 h to 30-45 min. Conversion of all the selenium to selenite (SeIV) was optimized by addition of 1 ml of concentrated hydrochloric acid, with heating to 100 degrees C for 30 min. The rate of formation of the 2,3-diaminonaphthalene (DAN) complex of selenium was improved by heating to 70-100 degrees C for a minimum of 30 min. Co-addition of hexane during derivatization simplified the extraction procedure. The modified method was applied successfully to the analysis of Seronorm quality control whole blood and urine (83 and 24 micrograms l-1 Se, respectively). Samples from 12 healthy adults, gave results in expected ranges (mean concentrations of 75 +/- 8 micrograms l-1 in blood and 25 +/- 8 micrograms l-1 in urine). The structure of the Se-DAN complex was investigated using elemental analysis, FTIR spectrometry, 1H and 13C NMR spectroscopy, and FAB MS. The information obtained indicates that the selenodiazo group does not contain an Se-O bond or protonated nitrogens, as proposed in other studies.
authors.affiliation: Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, UK.
authors.forename: I
authors.initials: I
authors.lastname: Harrison
authors.forename: D
authors.initials: D
authors.lastname: Littlejohn
authors.forename: G S
authors.initials: GS
authors.lastname: Fell
mesh_terms: D000328:Adult; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D012643:Selenium / Q000032:analysis*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods
chemical_list: D012643:Selenium