title: Development of extraction methods for speciation analysis of selenium in aqueous extracts of medicinal plants.
abstract: Advanced extraction methods have been developed for direct speciation of dissolved inorganic and organic selenium (Se) species in aqueous extracts of medicinal plants (MPs). The inorganic species of Se (SeIV and SeVI) were separated from organic forms by adsorbing inorganic Se on alumina, while the organic Se was not retained. The retained inorganic Se species was eluted with 10 mL 0.2 M HCl. The total inorganic Se species was determined after prereduction of SeVI into SeIV with concentrated HCl. The SeIV in the eluent and total inorganic Se species were then complexed with diethyldithiocarbamate. The resultant complexes were entrapped in the nonionic surfactant Triton X-114. The total Se, organic Se, total inorganic Se, and SeIV species were determined by electrothermal atomic absorption spectrometry with a modifier. The SeVI concentration was obtained by subtracting SeIV from total inorganic Se contents. The main factors affecting the methodologies were investigated in detail. Under the optimized experimental conditions, the LOD for SeIV was 50 microg/L. Among dissolved inorganic and organic Se species in aqueous extracts of MPs, organic Se species were present in the range of 74-84%, SeIV 3.62-7.47%, and SeVI 12.4-18.57% of total Se contents.
authors.affiliation: University of Sindh, Center of Excellence in Analytical Chemistry, Jamshoro, Pakistan. nidafatima6@gmail.com
authors.forename: Nida F
authors.initials: NF
authors.lastname: Kolachi
authors.forename: Tasneem G
authors.initials: TG
authors.lastname: Kazi
authors.forename: Hassan I
authors.initials: HI
authors.lastname: Afridi
authors.forename: Sumaira
authors.initials: S
authors.lastname: Khan
authors.forename: Jameel A
authors.initials: JA
authors.lastname: Baig
authors.forename: Sham K
authors.initials: SK
authors.lastname: Wadhwa
authors.forename: Abdul Q
authors.initials: AQ
authors.lastname: Shah
authors.forename: Faheem
authors.initials: F
authors.lastname: Shah
mesh_terms: D006863:Hydrogen-Ion Concentration; D010936:Plant Extracts / Q000737:chemistry*; D010946:Plants, Medicinal / Q000737:chemistry*; D012643:Selenium / Q000032:analysis*; D014867:Water / Q000737:chemistry*
chemical_list: D010936:Plant Extracts; D014867:Water; D012643:Selenium