4th Trace Element 2008

PP036 - Method Development for Selenium Speciation in Selenium Nutritional Supplements and Urine using HPLC-HG-AFS

Authors: Dr Bin Chen, Tessy A Momoh, Dr Warren T Corns and Dr Peter B Stockwell (PSA)

A new technique for the speciation of selenocysteine, selenomethionine, selenite, selenate and selenosugar1 was developed using high performance ion-pair reverse phase chromatography coupled with atomic fluorescence spectrometry.

Selenium species were separated using a mobile phase of pH 4 containing 40mM ammonium formate, 0.01mM DDAB, 0.5% (v/v) methanol at 0.8ml min-1 on a Gemini C18 column (250 x 4.6mm, 5µm) and then digested by online ultra violet (UV) irradiation at elevated temperature. Hydride generation was used as sample introduction technique, and this was maximized for all species by the optimization of variable analytical parameter. The final optimized conditions for UV-HG-AFS were 50% (v/v) HCl + 5% (m/v) KBr as oxidant, 0.8% (m/v) NaBH4 in 1% (m/v) NaOH as reductant, 250ml min-1 argon flow rate and 150°C temperature. Selenium nutritional supplements and urine samples were analyzed, and the detection limit obtained was range 0.9ng ml-1 to 3ng ml-1. One of the most significant findings of this research was that selenomethionine was found to be metabolized to selenosugar1 and excreted in urine.

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