Measurement by reversed-phase high-performance liquid chromatography of malondialdehyde in normal human urine following derivatisation with 2,4-dinitrophenylhydrazine

A selective and sensitive method based on derivatisation with 2,4-dinitrophenylhydrazine (DNPH) and consecutive HPLC gradient separation is described for the determination of malondialdehyde (MDA) in urine. Preparation of urine samples involved a one-step derivatisation/extraction procedure. Separation was achieved using a Waters Symmetry™C18 column (3.9x150 mm) and linear gradient of acetonitrile in water (from 30% to 70% in 30 min). The overall detection limit of the method was 56 nM of MDA in urine. The recovery of MDA was 94.3±8.6%. MDA in urine of healthy volunteers, measured using the method of standard additions, was 0.019±0.012 μmol/mmol creatinine. MDA in the same samples measured using the 2-thiobarbituric acid (TBA) assay was 0.181±0.063 μmol/mmol creatinine. We demonstrate that the commonly used TBA assay in conjunction with HPLC may overestimate the MDA concentration in human urine by almost 10-fold.