Determination of lactose in sugar-free milk powder by capillary electrophoresis with electrochemical detection

Lactose in three sugar-free milk powder samples were satisfactorily determined by capillary electrophoresis with electrochemical detection using a 300 μm copper disk electrode as the working electrode in 0.1 mol/l NaOH medium. There was acceptable linearity (0.9969) between the peak current and concentration of lactose in the range from 5.0×10−6 to 5.0×10−3 g/ml with the detection limit (S/N=3) of 1×10−7g/ml. The proposed method was successfully applied to analyze the actual milk powder samples.