Recovery of malondialdehyde in urine as a 2,4-dinitrophenylhydrazine derivative analyzed with high-performance liquid...

Malondialdehyde (MDA) in urine was measured as a 2,4-dinitrophenylhydrazine (DNPH) derivative using high-performance liquid chromatography (HPLC) for the analysis. MDA standard coeluted with a peak obtained from rat urine after i.p. administration of MDA standard. This peak was also the only peak containing 14C after injection of a [14C]MDA standard, and was shown by mass spectrometry to contain 1-(2,4-dinitrophenyl)pyrazole, the derivative formed when MDA is treated with DNPH. Depending on the amount given (0.3-5.5 mumol), the recovery (after 24 h sampling period) in urine was 0.7-2.6%. This apparent non-linear kinetics may relate to several factors, such as dose-dependent metabolism. However, the peak urinary concentration approached the expected plasma concentration and reproducible recovery data were obtained, suggesting that MDA was passively excreted in a reasonably stable form. These data indicate that monitoring MDA excretion in urine can give useful information about lipid peroxidation in vivo.