To observe oxidative modifications of serum albumin (OMSA) in radiation-exposed mice over time, mice were irradiated with 0, 1, and 3 Gy of X-rays, and blood was collected from the fundus on days 1, 30, 60, and 80. The number of samples was 4 mice per group. The collected sera were subjected to reductive alkylation and trypsinization according to the usual methods. Multiple reaction monitoring (MRM) measurements were performed using LC-MS/MS targeting 48 OMSA peptides and non-modified peptides.