Determination of monoamine oxidase activity by capillary electrophoresis

A method was developed for the rapid determination of monoamine oxidase (MAO) by capillary electrophoresis. The effect factors including the pH of running buffer, the concentration of electroosmotic flow modifier, the concentration of running buffer' were investigated. The analysis was performed in an uncoated fused-silica capillary with 50 μm id and a total length of 70 cm (40 cm to the detector) under the applied voltage of 15 kV with a running buffer of 50 mmol/L phosphate buffer saline (PBS) and 0.5 mmol/L tetrade-cyltrimethyl ammonium bromide (TTAB) (pH 10.5, adjusted with 1 mol/L NaOH), detected by UV detector at 214 nm. The linear range between response and 4-hydroxyquinoline concentration, which is the product of the MAO cactalyzed reaction, was from 5 μmol/L to 1 mmol/L, with correlation coefficient of 0.9997. The precision of the method was 5.6% (n = 5). The limit of detection was 2 μmol/L(S/N = 3). The analysis can be finished within 10 min. This method can be used to detect the MAO activity in biological specimen.