title: Electron paramagnetic resonance study of iron oxalate in calcium oxalate renal stones.
abstract: Weak electron paramagnetic resonance (EPR) signals from a number of calcium oxalate renal stones are attributed to an iron oxalate component. The g-value of the resonance is 2.0036 and its width is approximately 9 gauss. The EPR resonance from stones has the same characteristics as resonances from iron introduced into calcium oxalate and oxalic acid as an impurity. A sharp increase in EPR signal when calcium oxalate renal stones are exposed to intense light is attributable to the reduction of Fe3+ and the formation of the oxalate radical ion (C2O4)-.
mesh_terms: D002129:Calcium Oxalate / Q000032:analysis / Q000378:metabolism*; D055598:Chemical Phenomena; D002621:Chemistry; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D007501:Iron / Q000032:analysis* / Q000378:metabolism; D007669:Kidney Calculi / Q000378:metabolism*; D010070:Oxalates / Q000378:metabolism
chemical_list: D010070:Oxalates; D002129:Calcium Oxalate; D007501:Iron