Investigation of the stability of selenoproteins during storage of human serum by size-exclusion LC–ICP-MS

The stability of selenium-containing proteins in human serum was investigated by size-exclusion chromatography–ICP-MS under non-denaturating conditions. The peak characteristic to glutathione peroxidase (GSHPx) (tetramer) was the most affected; peaks of the GSHPx monomer and of selenite were found to appear with time. No trace of selenite was present in fresh samples, which suggest that the presence of this species in serum may be an artifact of storage. The mass balance of selenium species indicates that some of selenium is lost as a function of the storage time.