A stable-isotope HPLC–MS/MS method to simplify storage of human whole blood samples for glutathione assay

Background hione is the principal non-protein tripeptide thiol present in most mammalian cells and plays an important role in the redox status of biological systems. The accurate assessment of reduced glutathione (GSH) status as a reliable index of oxidative stress is of research and clinical significance. GSH undergoes rapid oxidation after sample collection and this presents a challenge. s tion of an HPLC–MS/MS assay is reported. Storage stability using four variants of a methanolic precipitation with addition of stable isotope internal standard at collection is compared to l-serine borate/EDTA with perchloric acid precipitation (SBPE). s itation with methanol and addition of stable isotope on sample collection, combined with storage in solution at −70 °C showed superior storage stability to SBPE and other variants of the methanolic precipitation method up to 99 days. sions mbination of stable isotope with methanolic precipitation at collection, with assay by HPLC–MS/MS provides superior results after storage of whole blood samples for at least 99 days.