Monoclonal antibody-based ELISA for the quantification of nitrofuran metabolite 3-amino-2-oxazolidinone in tissues using a simplified sample preparation

A sensitive and specific monoclonal ELISA for the determination of tissue bound furazolidone metabolite 3-amino-2-oxazolidinone (AOZ) is described. The procedure enables the detection of AOZ in matrix supernatant after homogenisation, protease treatment, acid hydrolysis and derivatisation of AOZ released from the tissue by o-nitrobenzaldehyde. The formed p-nitrophenyl 3-amino-2-oxazolidinone (NPAOZ) is determined by ELISA calibrated with matrix-matched standards in the concentration range of 0.05-5.0 μg I−1. The assay was validated according to criteria set down by Commission Decision 2002/657/EC for the performance and validation of analytical methods for chemical residues. Detection capability, set on the basis of acceptance of no false negative results, was 0.4 μg kg−1 for shrimp, poultry, beef and pork muscle. This sensitivity approaches the established confirmatory LC-MS/MS able to quantify tissue-bound AOZ at levels as low as 0.3 μg kg−1. An excellent correlation of results obtained by ELISA and LC/MS-MS within the concentration range 0-32.1 μg kg−1 was found in the naturally contaminated shrimp samples (r = 0.999, n = 8). A similar correlation was found for the incurred poultry samples within the concentration range of 0-10.5 μg kg−1 (r = 0.99, n = 8).