Determination of ascorbic acid in individual rat hepatocyte by capillary electrophoresis with electrochemical detection

A method for the direct determination of ascorbic acid (AA) in individual rat hepatocyte based on capillary electrophoresis (CE) coupled with electrochemical detection (ECD) using a new kind of homemade carbon fiber micro-disk bundle electrode has been described. Individual rat hepatocytes were injected into a fused-silica capillary with an inner diameter of 25 μm, and lysed by 0.1% sodium dodecylsulfate (SDS) as cell lysis solution. The following conditions were suitable for the determination of AA: running buffer, 1.83 × 10−2 mol/l Na2HPO4–1.70 × 10−3 mol/l NaH2PO4 (pH 7.8); separation voltage, 20.0 kV; detection potential, 0.80 V (vs. saturated calomel electrode (SCE)). The concentration limit of detection (LOD) of the method was1.7 × 10−6 mol/l at a signal-to-noise (S/N) ratio of 3, and the mass LOD was 3.0 fmol. The linear dynamic range was from 5.0 × 10−6 to 5.0 × 10−4 mol/l with a correlation coefficient of 0.9962 for the injection voltage of 5.0 kV and injection time of 10 s. The relative standard deviation (R.S.D.) was 0.85% for the migration time and 1.8% for the peak current. This method was successfully applied to AA determination in rat hepatocyte. The recovery was between 91% and 97%, and the amount of AA in single rat hepatocyte ranged from 28 to 63 fmol.