Diaminonaphtalene, a new highly specific reagent for HPLC-UV measurement of total and free malondialdehyde in human plasma or serum

We describe a new method to measure free and total malondialdehyde (MDA) in human plasma or serum, which is based on the derivatization of MDA with di aminonaphtalene (DAN) in an acidic medium at 37 degreesC. Derivatization is complete after 180 min at room temperature. By HPLC separation on a C18 co lumn and diode array detection, the diazepinium thus formed exhibits a high ly specific UV spectrum with a sharp maximum at 311 nm, which clearly disti nguishes MDA from other short-chain aldehydes. Direct injection of deprotei nized plasma avoids the use of an internal standard. The between-run imprec ision is 9.1% (141 +/- 13 nM) for plasma and 6.6% (658 +/- 44 nM) for a com mercial control. Typical within-day imprecision is 8% (93 +/- 7.5 nM) for t otal MDA, 3.2% (16 +/- 0.5 nM) for free MDA in plasma, and 1.6%, (630 +/- 1 0 nM) for a commercial control. The recovery of MDA added to 10 different p lasmas is 93-108% (mean = 100%). Plasma levels in healthy women (n = 79, 45 -51 years) are 162 +/- 51 and 24 +/- 15 nM for total and free MDA, respecti vely. In younger men (n = 19, 21-37 years) total and free MDA are, respecti vely, 138 +/- 28 and 19 +/- 9 nM. (C) 2001 Elsevier Science Inc.