Validation of a reference measurement procedure for the assessment of selenomethionine in nutritional supplements

Abstract

The development of a metrological protocol in order to enhance traceability in speciation analysis of selenium is presented. The measurement procedure is applied for the determination of selenomethionine and total selenium in two nutritional supplements, in particular certified reference material to validate the method. Extraction protocols are tested for their capability to leach out total selenium and selenomethionine from the samples. Speciation analysis is realised with the use of HPLC-ICP-MS. Isotope dilution is employed to determine the analytes contents. An uncertainty budget is elaborated with the method recommended by the Guide to the expression of Uncertainty in Measurement (GUM).