Abstract: The difference method associated with biosensor was used in this study by immobilizing glucose oxidase as well as composite enzyme consisting of galactosidase and glucose oxidase onto dual hydrogen peroxide electrodes. The levels of lactose and glucose in the sample could be simultaneously determined. The results showed that the biosensor method revealed a good linearity in the lactose range of 0.00~1.50 g/L and glucose range of 0.00~1.00 g/L,the stability of the biosensor was favourable, the relative standard deviation was 1.49%, and the adding standard recovery rate ranged from 95% to 105%,no significant difference (P>0.05) was noted in the measurement results between this method and HPLC. Therefore, the difference method associated with composite enzyme membrane biosensor proposed in this study can be used for the detection of lactose in milk.

Key words: lactose, glucose, biosensor, milk