Enriched stable isotopes and isotope pattern deconvolution for quantitative speciation of endogenous and exogenous selenium in rat urine by HPLC-ICP-MS

Interest in selenium metabolism and its role in health and disease continue to stimulate a lot of bioanalytical research. The use of enriched stable isotopes of Se and isotope pattern deconvolution (IPD) with an ICP-MS in lactating rats is approached here for total selenium distribution studies. A mathematical tool has been developed to calculate supplemented and endogenous total Se contents in urine and faeces by ICP-MS. Also, quantification of endogenous (natural) and exogenous seleno-species by HPLC-ICP-MS has been worked out. The proposed IPD methodology, for total determinations and for quantitative speciation, was applied to reference materials to validate total selenium quantification in faeces and quantitative selenium speciation in urine samples. Selenium apparent absorption and retention and natural and exogenous selenium distribution in urine samples were calculated. Interesting quantitative information about selenium bio-transformations and final catabolism can be obtained from careful examination of the results observed, using such analytical tools, of the urinary endogenous and exogenous selenium metabolites in urine of rats and their kinetics throughout the two weeks of selenium supplementation.