Isoprostane measurement in plasma and urine by liquid chromatography-mass spectrometry with one-step sample preparation

plasma and urine is widely accepted as a measure of oxidative stress. Gas chromatography–mass spectro-metry (GC/MS) methods for measuring iPF2-III involve several steps of sample preparation and are labor-inten-sive, and ELISAmethods, although easier to use, are less reliable. Therefore we developed a simple and sensitive method involving 1-step sample cleanup and HPLC/MS quantification. Methods: Samples of plasma or urine were enriched with a deuterated (iPF2-III-D4) standard, treated with KOH to liberate the bound isoprostanes, then loaded onto an immunoaffinity column, and the bound isopros-tane was eluted with 95 % ethanol. The concentrated sample was injected onto a C-18 HPLC column, and the isoprostane was eluted with a gradient of acetonitrile i