title: Determination of beta-lactams in milk using a surface plasmon resonance-based biosensor.
abstract: Two surface plasmon resonance (SPR)-based biosensor assays for detection of beta-lactam antibiotics in milk are reported. The assays are based on the enzymatic activity of a carboxypeptidase converting a 3-peptide into a 2-peptide, a reaction that is inhibited in the presence of beta-lactams. Antibodies were used to measure either the amount of formed enzymatic product or the amount of remaining enzymatic substrate. Both assays detected different beta-lactams at or below European maximum residue limits (MRLs), and the detection limit for penicillin G was 1.2 microg/kg and 1.5 microg/kg for the 2- and 3-peptide assays, respectively. The precision (CV) was < 5%, both within and between assays at the penicillin G MRL (4 microg/kg). The biosensor results obtained upon analysis of incurred milk samples were compared with results obtained by liquid chromatography (HPLC), and the method agreements were, in general, good.
authors.affiliation: Department of Food Science, Swedish University of Agricultural Sciences, P.O. Box 7051, 750 07 Uppsala, Sweden.
authors.forename: Eva
authors.initials: E
authors.lastname: Gustavsson
authors.forename: Jacques
authors.initials: J
authors.lastname: Degelaen
authors.forename: Peter
authors.initials: P
authors.lastname: Bjurling
authors.forename: Ase
authors.initials: A
authors.lastname: Sternesjö
mesh_terms: D000818:Animals; D002268:Carboxypeptidases; D002851:Chromatography, High Pressure Liquid; D008892:Milk / Q000737:chemistry*; D010400:Penicillin G / Q000032:analysis; D012680:Sensitivity and Specificity; D020349:Surface Plasmon Resonance; D047090:beta-Lactams / Q000032:analysis*
chemical_list: D047090:beta-Lactams; D002268:Carboxypeptidases; D010400:Penicillin G