Free malondialdehyde determination in rat brain tissue by capillary zone electrophoresis: evaluation of two protein removal procedures

Two procedures for the determination of underivatised, free malondialdehyde in rat brain tissue have been evaluated. Both procedures are based on capillary zone electrophoresis (CZE) and UV detection at 267 nm and differ only with respect to the protein removal step, for which ultrafiltration or precipitation with acetonitrile have been employed. The total analytical processes include sample homogenisation, addition of antioxidant, protein removal, and separation and detection in the CZE system, and take less than 20 min. The CZE buffer consists of 10 mM borax and 0.5 mM CTAB at pH 9.3. The malondialdehyde peak reaches the detector about 3 min after injection as one of the very first peaks in the electropherogram. The limit of detection (3 S/N) is 0.2 μM, corresponding to 4 fmol for an injection volume of 20 nl. The method is fast, reproducible and has a large linear range, spanning 0–200 μM.