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An immunobiosensor assay was developed for multi-residue screening in bovine milk of the parent amphenicols, thiamphenicol and florfenicol, along with the metabolite florfenicol amine. A polyclonal antibody raised in a rabbit after immunisation with a florfenicol amine-protein conjugate was employed in the assay. Milk samples were subjected to acetonitrile extraction, reconstituted in buffer and diluted prior to biosensor analysis. Validation data obtained from the analysis of fortified samples has shown that the method has a detection capability of less than 0.25 µg kg -1 for florfenicol and less than 0.5 µg kg -1 for florfenicol amine and thiamphenicol. The cross-reactivity profile and validation data for the detection of these amphenicols is presented together with results obtained following the analysis of florfenicol incurred samples using the developed screening method along with a comparison of results obtained from the analysis of the same incurred samples using an MRM 3 UPLC-MS/MS confirmatory method. Results are also presented obtained from the analysis of samples from both treated and non-treated animals which were co-housed and which show the potential for cross-contamination.

An immunobiosensor assay was developed for the multi-residue screening of the parent amphenicols, thiamphenicol and florfenicol, along with the metabolite florfenicol amine, in bovine, ovine and porcine kidney. A polyclonal antiserum raised in a rabbit after inoculation with a florfenicol amine-protein conjugate was employed in the assay. Sample homogenates were extracted directly into acetonitrile, reconstituted in buffer and diluted prior to biosensor analysis. Validation data obtained from the analysis of fortified samples has shown that the method has a detection capability (CCβ) of less than 25µgkg -1 (1/2 MRL) for thiamphenicol in the kidney of all three species, less than 150µgkg -1 (1/2 MRL) for florfenicol and florfenicol amine and less than 250µgkg -1 (1/2 MRL) for florfenicol and florfenicol amine in bovine/ovine and porcine kidney respectively. Intra-assay variation (n=10) was calculated at 4.5% and 2.6% at concentrations of 10µgkg -1 and 150µgkg -1 respectively for bovine kidney while inter-assay variation (n=3) was determined to be 5.0% and 16.5% respectively at the same concentrations. The cross-reactivity profile and validation data for the detection of these amphenicols is presented together with the results obtained following the analysis of florfenicol incurred samples using the developed method., (Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.)

Phenylbutazone is a non-steroidal anti-inflammatory drug licensed for use in horses to treat musculoskeletal disorders. It is not permitted in the European Union for use in animals destined for the food chain. Official statistics provided by the European Food Safety Authority (EFSA) show that 0.18% of bovines tested in the European Union between 2008 and 2014 for non-steroidal anti-inflammatory drugs were non-compliant, with phenylbutazone representing over 28% of these. Anecdotal evidence suggests animals that have not been treated with the drug may have produced non-compliant samples, possibly through some form of contamination. In this study, ultra-high-performance liquid chromatography coupled with mass-spectrometric detection was applied to bovine plasma samples to determine if detectable residues (CCα = 0.28 ng ml -1 ) may occur in untreated animals as a result of environmental contamination through normal farming practice. The study demonstrates that waste from animals treated with phenylbutazone, and spread on an area of pasture, can contaminate untreated bovines grazing the pasture many weeks later. It was determined that this contamination, which can persist over a significant period, may be due to the ingestion of as little as 30 μg phenylbutazone by a 500 kg bullock.