Determination of antibiotic residues and their interaction in milk with lactate biosensor

Milk and dairy products are among the most important foodstuffs and the quality of raw milk is of significant importance from the point of view of human health. For rapid determination of chloramphenicol and penicillin residues in raw milk, lactate oxidase-based amperometric biosensor was used. The concentration of antibiotic residuals was determined by two characteristic reaction parameters, calculated from the biosensor transient response with the dynamic biosensor model. Both chloramphenicol and penicillin caused the decrease of the value of the kinetic parameter, but they changed the total signal change parameter in different ways. The shift of the combined total signal change parameter at the simultaneous presence of these antibiotics indicated their antagonistic effect. Due to the respiration process of bacteria in raw milk, the dynamics of the biosensor signal was different in warm and cold seasons. The respiration characteristics were added to the biosensor model as a negative linear time-depending factor. The reaction characteristic parameters, obtained with this complemented model, showed excellent alignment in different conditions and allowed to detect antibiotic residues and their interaction in raw milk. (c) 2005 Elsevier B.V. All rights reserved.