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−1in working buffer, and an LOD of 0.98 ng g−1; the detection range was from 0.98 to 51.6 ng g−1in 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.Keywords:zearalenone;contamination;magnetic bead immunoassay;corn;corn product;swine feedKey Contribution:In total, 405 corn and related product samples from China in 2016–2018 were surveyed for zearalenone contamination using a high-efficiency magnetic bead immunoassay.
Ming Li,Yuanyuan Zhang,Yonglai Xue,Xia Hong,Yin Cui,Zhenjiang Liu,Daolin Du
Lanthanide ions, the excellent fluorescence markers, have the potential to simplify the performance of multi-analytes analysis. In this work, a powerful time-resolved fluoroimmunoassay (TRFIA) based on dual-labeled format were performed for detecting clenbuterol and salbutamol simultaneously in water and swine feed samples. Europium (Eu 3+ )-labeled goat anti-mouse IgG and Samarium (Sm 3+ )-labeled goat anti-rabbit IgG were prepared and used as fluorescent probes. Under optimal conditions, the half-maximal inhibition concentration (IC 50 ) and the limit of detection (LOD, IC 10 ) of the TRFIA were 0.263 and 0.007 ng/mL for clenbuterol, and 0.179 and 0.014 ng/mL for salbutamol, respectively. The cross-reactivities of the TRFIA between these two β 2 -agonists and with their analogues were negligible, thus indicated high specificity and promoted the simultaneous determination. The spiked recoveries were 72.2%–102.2% with relative standard deviations (RSDs) of 3.4–13.8% for clenbuterol and salbutamol in water and swine feed samples. Furthermore, the results of TRFIA correlated well with those obtained by HPLC. The proposed dual-labeled TRFIA was a satisfactory tool for simultaneous, sensitive, efficient and labour-saving detection of clenbuterol and salbutamol in water and swine feed samples.
Tian Gan,Zhaoxia Shi,Danyang Hu,Zhen Lv,Junyong Sun,Yanming Liu
In this paper, we report a facile route to synthesize yolk–shell structured copper oxide@silica oxide (CuO@SiO 2 ) spheres and their application to construct an electrochemical Formoterol fumarate (FF) sensor. The CuO@SiO 2 was characterized by means of Fourier transform infrared spectroscopy, X-ray powder diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. Further, FF was electrocatalytically oxidized at the CuO@SiO 2 film modified glassy carbon electrode (GCE), which led to a sensitive determination of FF. The oxidation current of FF was linear with concentration in the range of 0.030–10 μM and the detection limit was found to be 5.0 nM (S/N = 3). The observed analytical parameters such as wide linear range, low detection limit and short response time were superior to previously reported FF sensors. Finally, it was demonstrated that the proposed sensor could be used for the selective determination of FF present in swine feed and tissues.
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