Submitted to: Analytica Chimica Acta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/28/2010
Publication Date: 1/14/2011
Citation: Keegan, J., O'Kennedy, R., Crooks, S., Elliott, C.T., Brandon, D.L., Danaher, M. 2011. Detection of benzimidazole carbamates and amino metabolites in liver by surface plasmon resonance-biosensor. Analytica Chimica Acta. 700(1-2):41-48. Interpretive Summary: A new analytical method was developed to screen liver samples rapidly for residues of benzimidazole veterinary drugs that are widely used for prevention and treatment of parasitic infections in agriculture and aquaculture. Because some of these anti-worm drugs are used to treat infected cows, analytical methods for detecting drug residues in the bovine liver matrix are needed to ensure compliance with regulatory guidelines. The method exploits an antibody that binds to these compounds, together with an optical biosensor to detect binding in samples containing residues at 50 - 75 ppb, well below the regulatory limit, with no false negatives and a false positive rate less than 5%. The comprehensive evaluation and validation of the assay was conducted according to current EU criteria for 15 drugs and metabolites. The results were compared to those from a confirmatory method that uses liquid chromatography and mass spectrometry.
Technical Abstract: Two surface plasmon resonance (SPR) biosensor screening assays were developed and validated to detect 11 benzimidazole carbamate (BZT) and four amino-benzimidazole veterinary drug residues in liver tissue. The assays used polyclonal antibodies, raised in sheep, to detect BZTs and amino-benzimidazoles. A modified Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) extraction method was developed to extract benzimidazole carbamate residues. Liver samples were extracted using an acetonitrile extraction method. BZTs were purified by dispersive solid phase extraction using a C18 sorbent. Residues of amino-benzimidazoles were effectively cleaned-up using a simple cyclohexane defatting step. The assays were validated in accordance with the performance criteria described in 2002/657/EC. The BZT assay limit of detection was calculated to be 32 µg kg-1, the detection capability (CCß) was determined to be 50 µg kg-1 and the mean recovery of analytes was in the range 77-132%. The amino-benzimidazole assay limit of detection was determined to be 41 µg kg-1, the CCß was determined to be 75 µg kg-1 and analyte recovery was in the range 103-116%. Biosensor assay performance was tested by analysing liver tissue from animals treated with benzimidazole drugs and comparing the results with a UPLC-MS/MS confirmatory method. All non-compliant samples were identified using the biosensor assays.