Quantification of selenomethionine in plasma using UPLC-MS/MS after the oral administration of selenium-enriched yeast to rats

- A UPLC-MS/MS method for analyzing SeMet in plasma was established.
- In vivo SeMet converted from selenium-enriched yeast was firstly reported.
- The oral absolute bioavailability of SeMet converted from SeY in rats was 87%.

The in vivo determination of selenomethionine (SeMet) converted from selenium-enriched yeast (SeY) rather than the determination of in vitro hydrolyzed SeMet is a better parameter for the evaluation of SeY quality. A UPLC-MS/MS method was developed for the quantification of SeMet in rat plasma and the oral bioavailability of SeMet converted from SeY in rats. After a simple extraction with perchloric acid, SeMet and the internal standard methylselenocysteine (MSC) were separated on a C18 column with isocratic elution of water:acetonitrile:formic acid (99:1:0.1, v/v/v) and detected in the multiple reaction monitoring mode. The method was accurate (92.6-104.3%) and precise (1.8-11.0%), and the recovery was 79.4-95.4%. It was successfully applied to pharmacokinetic and bioavailability studies of SeY in rats following the intravenous administration of SeMet and intragastric administration of SeY. SeMet in vivo, converted from SeY, is reported for the first time, and the results suggested that the SeY bioavailability in rats is 87%.