Simultaneous speciation of selenomethionine and 2-hydroxy-4-methylselenobutanoic acid by HPLC-ICP MS in biological samples.

An analytical method was developed for the simultaneous speciation of selenomethionine (SeMet) and 2-hydroxy-4-methylselenobutanoic acid (NutraSelen), a new SeMet precursor. The compounds could be baseline resolved by ion-pairing reversed-phase HPLC using ICP MS detection. Detection limits of 1 ng mL(-1) (Se content) could be reached. SELM-1 reference material was used to validate the SeMet measurement. Additionally, the quantification of NutraSelen was validated by standard addition together with checking the Se mass balance. The procedure developed was then applied to the monitoring of the conversion of NutraSelen into SeMet by yeast.