Abstract: An electrochemical enzyme biosensor was developed to determine hydrogen peroxide in milk. Thionine was electropolymerized on screen-printed electrode, followed by coating the electrode surface with horseradish peroxidase embedded in chitosan-silica sol-gel. The results showed that the response current of the sensor was linearly related to the concentration of hydrogen peroxide in milk samples over the range of 3×10-5 to 1.5×10-3 mol /L with a detection limit of 1.675 ×10-5 mol /L. Recovery rates ranging from 85.6% to 89.4% were obtained in the determination of real samples using the sensor and the results were agreed with those obtained from the Chinese national standard by iodometry method. This method is sensitive, fast and convenient and has potential for applications in the determination of hydrogen peroxide in milk.

Key words: electrochemical enzyme biosensor, hydrogen peroxide, milk