Rapid Determination of Cephalexin in Animal-Derived Food by an Indirect Competitive Enzyme-Linked Immunosorbent Assay

Cephalexin (CFE) residues in animal-derived food and its deleterious effects on human health has attracted extensive attention. In this study, a specific anti-cephalexin monoclonal antibody (mAb) was used to develop an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) with a half-maximal inhibitory concentration (IC50) of 1.83 µg/L that was suitable for the determination of cephalexin in animal-derived foods. The limit of detection (LOD) and limit of quantitation (LOQ) for cephalexin were from 0.44 to 0.58 µg/kg and 0.57 to 0.67 µg/kg, respectively. The recovery was from 90.1 to 103.6% with coefficients of variation (CV) less than 10.0%. In addition, the established ELISA method and high-performance liquid chromatography – mass spectrometry (HPLC-MS/MS) were used to analyze the samples with good correlation between the results. The results show that the established ic-ELISA is suitable for the determination of cephalexin in animal-derived food.