Detection of streptomycin and dihydrostreptomycin residues in milk,honey and meat samples using anoptical biosensor

摘要

Immuno-biosensor inhibition assays for the detection of streptomycin and dihydrostreptomycin residues in whole cows' milk,honey,pig kidney and pig muscle are reported.The antibody showed high cross-reactivity with dihydrostreptomycinin various foodstuffs (buffer 103%,milk 96%,honey 84%,kidney extract 129% and muscle extract 98%).There was no signigicant corss-reaction with other aminogly or commonly used antibiotics.A streptomycin derivative was used to rpepare a stable,reusable sensor chip surface.The assay alowed the direct analysis of bovine whole milk (fat content approx3.5%).Honeysamples required dilution with fuffer,while kidney and muscle samples from pigs were homogenized in an aqueous extraction buffer andclarified by centrifugation.The limit of detection for each assay was determined from known streptomycin-free samples (n=20;mean-(3*standard deviation) and the results were as follows:milk 30 mug kg~(-1),kidney 50 mug kg~(-1) and muscle 70 mug kg~(-1).Repeatability (or relative standard deviation) between runs were calculated (n=3) at the respective Community maximum residue limits (MRL) and 0.5*MRL with the exception of honey since no European MRL exists at present.Results were determined as 4.3% (200mug kg~(-1) and 2.8% (100 mug kg~(-1) in milk,13.3% (40 mu kg~(-1) and 9.5%(20 mug kg~(-1)) in honey,7.1% (1000 mug kg~(-1)) and 7.6%(500mug kg~(-1)) in kidney and 7.1% (500 mug kg~(-1) and 11% (250 mug kg~(-1) in muscle.