Quality Evaluation of Five Commercial Enzyme Linked Immunosorbent Assay Kits for Detecting Aflatoxin B1 in Feedstuffs

The objective of this study was to evaluate the quality of five commercial enzyme linked immunosorbent assay (ELISA) kits (A, B, C, D, and E) from different suppliers for detecting aflatoxin $B_1$ ($AFB_1$). $AFB_1$-free corn samples supplemented with different levels of $AFB_1$ (5, 10, and $20{\mu}g/kg$) were used as positive controls and 6 replicates of each control sample were tested to evaluate the accuracy and precision of these kits. In addition, we also evaluated the performance of these ELISA kits for $AFB_1$ in 30 feed samples, including corn, distillers dried grains with soluble, wheat samples, soybean meal, and poultry feed, which were verified by high performance liquid chromatography. Results showed that the coefficients of variation ranged from 1.18% to 16.22% in intra-plate and 2.85% to 18.04% in inter-plate for the determination of $AFB_1$. The half maximal inhibitory concentration for five kits ranged from 3.72 to $7.22{\mu}g/kg$. The quantitation limits of $AFB_1$ were all under the legal limit in China but somewhat inconsistent with kit instructions. Although the recovery rate of four of the five kits were either less than 90% or more than 110%, all these values were acceptable in practice. Two kits had high false positive rates (C and E). In conclusion, our results revealed that the qualities of five tested ELISA kits were significantly different.