Determination of Ochratoxin A in Cereals and Feeds by Ultra-performance Liquid Chromatography Coupled to Tandem Mass Spectrometry with Immunoaffinity Column Clean-up

Abstract

This paper describes the preparation of reusable immunoaffinity columns and the development of an ultra-performance liquid chromatography tandem mass spectrometry method combined with immunoaffinity column clean-up (IAC-UPLC-MS/MS) for the determination of ochratoxin A (OTA) in cereals and feeds. The monoclonal antibody (mAb) was produced from a stable hybridoma cell line (4H10), which belongs to the immunoglobulin G1 (κ-light chain) isotype. A competitive indirect enzyme-linked immunosorbent assay was used to characterize the mAb. The concentrations causing 50 % inhibition of binding of mAb to OTA-ovalbumin by free OTA, ochratoxin B, and ochratoxin C were 1.29, 4.78, and 0.94 ng mL−1, respectively. The IAC-UPLC-MS/MS method offers a limit of quantification (LOQ, S/N >10) ranging from 0.5 to 1.0 μg kg−1 and a limit of detection (LOD, S/N >3) ranging from 0.2 to 0.3 μg kg−1 in cereal and feed samples. The IAC-UPLC-MS/MS method offers a good LOQ and LOD for OTA in cereal and feed samples. The accuracy and precision at this level fall within the EU regulatory limit. This methodology has been validated in four different matrices (millet, maize, soybean, and swine finisher diet) with highly satisfactory results and applied to the analysis of samples collected from the markets.