New immunosensor for β-lactam antibiotics determination in river waste waters

The aim of the present research was to develop a single use, simple but highly sensitive amperometric immunosensor for penicillin G and other β-lactam antibiotics based on a “competitive assay”. The immunosensor developed uses an amperometric electrode for hydrogen peroxide as transducer and the peroxidase enzyme as marker. The results demonstrate the full validity of this immunosensor method which was optimized by comparing two different competitive operating formats. LOD was of the order of 10−10 M. The immunosensor developed displayed low selectivity toward all β-lactam antibiotics and higher selectivity toward other classes of non β-lactam antibiotics. In addition the Kaff value (about 108 M−1) was evaluated. Lastly, the immunosensor was used to test a β-lactam antibiotic “pool” and to recover penicillin G in common real matrices such as river waste water, obtaining good recoveries.