Quantitative Determination of Butocarboxim in Agricultural Products Based on Biotinylated Monoclonal Antibody

Zearalenone Contamination in Corn, Corn Products, and Swine Feed in China in 2016-2018 as Assessed by Magnetic Bead Immunoassay

In total, 405 samples of corn, corn products, and swine feed from China in 2016-2018 were surveyed for zearalenone (ZEN) contamination using a magnetic bead immunoassay-coupled biotin-streptavidin system (BAS-MBI). The developed BAS-MBI had a limit of detection (LOD) of 0.098 ng mL-1, with half-maximal inhibition concentration (IC50) of 0.71 ng mL-1 in working buffer, and an LOD of 0.98 ng g-1; the detection range was from 0.98 to 51.6 ng g-1 in authentic agricultural samples. The BAS-MBI has been demonstrated to be a powerful method for the rapid, sensitive, specific, and accurate determination of ZEN. The ZEN positivity rate reached the highest level of 40.6% in 133 samples in 2016; ZEN levels ranged from 1.8 to 1100.0 ng g-1, with an average level of 217.9 ng g-1. In 2017, the ZEN positivity rate was the lowest at 24.5% in 143 samples; ZEN levels ranged from 1.1 to 722.6 ng g-1, with an average of 166.7 ng g-1. In 2018, the ZEN positivity rate was 31.8% in 129 samples; ZEN levels ranged from 1.3 to 947.8 ng g-1, with an average of 157.0 ng g-1. About 20% of ZEN-positive samples exceeded maximum limit levels. An alternative method of ZEN detection and a valuable reference for ZEN contamination in corn and its related products in China are provided. This survey suggests the need for prevention of serious ZEN contamination, along with management for food safety and human health.

Quantitative Determination of Acetamiprid in Pollen Based on a Sensitive Enzyme-Linked Immunosorbent Assay

A sensitive biotinylated indirect competitive enzyme-linked immunosorbent assay (Bic-ELISA) was developed to detect acetamiprid pesticides in pollen, based on the heterogeneous coating antigen and biotinylated anti-acetamiprid monoclonal antibody. Under optimized experimental conditions, the detection limit for the Bic-ELISA was 0.17 ng/mL and the linear range was 0.25–25 ng/mL. The cross-reactivities could be regarded as negligible for the biotinylated antibodies with their analogues except for thiacloprid (1.66%). Analyte recoveries for extracts of spiked pollen (camellia pollen, lotus pollen, rape pollen) ranged from 81.1% to 108.0%, with intra-day relative standard deviations (RSDs) of 4.8% to 10.9%, and the average reproducibility was 85.4% to 110.9% with inter-assay and inter-assay RSDs of 6.1% to 11.7%. The results of Bic-ELISA methods for the Taobao’s website samples were largely consistent with HPLC-MS/MS. Therefore, the established Bic-ELISA methods would be conducive to the monitoring of acetamiprid in pollen.

Immunomagnetic bead-based biotin-streptavidin system for highly efficient detection of aflatoxin B1 in agricultural products

The potential homogeneous assay employing immunomagnetic beads (IMB) has been receiving attention as a screening tool in food-safety control; the method is simple, efficient, and does not require long incubation times or complex separation steps. In this study, a homogeneous immunoassay has been successfully developed and applied in the determination of aflatoxin B₁ (AFB₁) contamination in agricultural products by coupling IMB and the biotin-streptavidin (BSA) (BSA-IMB) system. Under optimal conditions, the limit of detection (LOD, IC₁₀), half-maximal inhibition concentration (IC₅₀) and detection range (IC₂₀–IC₈₀) of BSA-IMB are 0.00579, 0.573 and 0.0183–17.9 ng mL⁻¹, respectively, for AFB₁. The detection of AFB₁ by BSA-IMB can be achieved in 40 min (ELISA needs at least 180 min). The cross-reactivities of BSA-IMB with its analogues are negligible (<3.82%); these results indicate high selectivity. The spiked recoveries are in the range from 89.6 to 118.2% with relative standard deviations (RSDs) of 3.4 to 13.2% for AFB₁ in agricultural product samples. Furthermore, the results of BSA-IMB for authentic samples show reliability and high correlation of 0.9928 with an HPLC-fluorescence detector. The proposed BSA-IMB system is demonstrated to be a satisfactory tool for homogeneous, efficient, sensitive, and alternative detection of AFB₁ in a wide detection range for agricultural product samples.

A strategy of immunomagnetic beads coupled with biotin-streptavidin system (BAS-IMB) for detecting AFB₁ was suggested and applied in agricultural products.