The application of an optical biosensor (Biacore 3000), with four flow channels (Fcs), in combination with a mixture of four specific antibodies resulted in a competitive inhibition biosensor immunoassay (BIA) for the simultaneous detection of the five relevant aminoglycosides in reconstituted skimmed milk. Four aminoglycosides (gentamicin, neomycine, kanamycin and a streptomycin derivative) were immobilised onto the sensor surface of a biosensor chip (CM5) in the four Fcs of the biosensor system by amine coupling. In the Biacore, milk (reconstituted from skimmed milk powder) was 10 times diluted with a mixture of the four specific antibodies and injected through the four serially connected Fcs (1 min at a flow rate of 20 ¿l min¿1). The responses measured just prior to the injection (20 ¿l at a flow rate of 20 ¿l min¿1) of the regeneration solution (0.2 M NaOH + 20% acetonitril) were indicative for the presence or absence of the aminoglycosides in reconstituted milk. The limits of detection were between 15 and 60 ng ml¿1, which was far below the maximum residue limits (MRLs) (varying from 100 to 500 ng ml¿1) and the total run time between samples was 7 min.
- performance liquid-chromatography
- (dihydro)streptomycin residues
- optical immunobiosensor
- antibiotic residues