Development and optimisation of an amperometric immunosensor for the detection of banned antibiotic residues in honey

Veterinary drugs could contaminate animal derived food products for human consumption. Some antibiotic residues (eg. chloramphenicol, nitrofuran metabolites) are banned in foodstuffs of animal origin (eg. milk, honey, etc.) in European Union because of toxicological risks for the consumer. Screening methods are the first stage of food control and so are essential for food safety monitoring. There is always a need to develop novel screening methods for antibiotic residues detection, preferably with the potential for the field-testing (eg. farm control, self-control). Electrochemical biosensors make it possible to develop a promising and economically interesting approach.

An innovative and cheap electrochemical method based on disposable Screen Printed Carbon Electrodes (SPCE), coupled to magnetic beads (MB), allowing the simultaneous detection of 3 families of antibiotics in milk, was published by a Spanish academic team [1]. This system was applied to develop a screening method for banned antibiotic residues in honey. We faced two major issues: firstly, the very low levels of residues to be reach (ie. Regulatory limits usually below 1 µg/kg), secondly the complexity of honey matrix. There is not a single honey matrix, but a wide variety of honeys. Honey composition and colour varies considerably depending on the botanical origin. Moreover some honey ingredients can interfere with the electrochemical detection, especially substances with antioxidant activities (eg. polyphenols).

Therefore in parallel with the optimization of the electrochemical method to reach the required sensitivity, a lot of work had to be done to improve sample extraction to reduce matrix effects. The results will be presented to the conference, discussing the advantages and drawbacks of amperometric biosensors for the screening of antibiotic residues in food products.

1. Conzuelo F, Ruiz-Valdepeñas Montiel V, Campuzano S, Gamella M, Torrente-Rodríguez RM, Reviejo AJ, Pingarrón JM. 2014. Anal. Chim. Acta. 820:32-38.