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A rapid, simple, and sensitive fluorescent immunochromatographic strip test (ICST) based on quantum dots (QDs) has been developed to detect 1-aminohydantoin (AHD), a major metabolite of nitrofurantoin in animal tissues. To achieve this, QD-labeled antibody conjugates, which consist of CdSe/ZnS QDs and monoclonal antibodies, were prepared by an activated ester method. Under optimal conditions, with the nitrophenyl derivative of AHD as the target, the ICST had a linear range from 0.1 to 100 ng/mL, with a correlation coefficient of 0.9656 and a 50% inhibitory concentration of 4.51 ng/mL. The limit of detection was 0.14 ng/g, which was below the minimum required performance limit of 1 μg/kg for AHD established by the European Commission. The recoveries for AHD ranged from 81.5% to 108.2%, with coefficients of variation below 13%, based on intraday and interday analysis. Furthermore, for AHD in real samples, the ICST showed high reliability and high correlation with liquid chromatography-tandem mass spectrometry (correlation coefficient of 0.9916). To the best of our knowledge, this is the first report of a novel and sensitive method based on a fluorescent ICST to detect AHD below the minimum required performance limit. The ICST demonstrated high reliability, and could be ideally suited for rapid, simple, and on-site screening of AHD contamination in animal tissues. Graphical abstract A rapid, simple, and sensitive fluorescent immunochromatographic strip test that is based on quantum dots was developed to detect 1-aminohydantoin (AHD), a major metabolite of nitrofurantoin in animal tissues. 2-NBA 2-nitrobenzaldehyde, NP nitrophenyl.

Abuse of pyrimethanil in crops to cause deleterious effects on humans has been of great concern. In this study, functionalized derivatives of pyrimethanil have been synthesized and conjugated to carrier proteins, and highly specific and sensitive monoclonal antibodies (mAb) have been produced. Based on the mAb 1F05, an ic-ELISA was developed and characterized for the analysis of pyrimethanil residues. The standard curves based on the pyrimethanil matrix calibration ranged from 0.03 to 3 ng/mL, with a 50% inhibitory concentration of 0.25 ng/mL. The limits of detection were 0.02-0.04 μg/kg in various matrices. The recoveries for pyrimethanil ranged from 88.6% to 102.3%, with coefficient of variation below 11%. A good correlation (R 2 > 0.9825) between the ic-ELISA and HPLC-MS/MS showed the reliability of the developed ic-ELISA. The proposed ic-ELISA was demonstrated to be a simple, rapid, and sensitive tool to monitor the residues of pyrimethanil in fruits and vegetables.

To monitor the levels of furaltadone in animal tissues, an immunochromatographic strip (immunostrip) based on quantum dot was developed for rapid detection of 3-amino-5methylmorpholino-2-oxazolidinone (AMOZ), the metabolite of furaltadone. Four monoclonal antibodies (mAbs) against nitrophenyl derivative of AMOZ (2-NP-AMOZ) were generated from the hybridoma cell lines. Among them, the mAb 5C10/3A8 showed the highest sensitivity to 2-NP-AMOZ. Using an immunostrip reader, with the 2-NP-AMOZ as the target, the immunostrip had a liner range from 1 to 30 ng/mL, with 50% inhibition concentration of 5.22 ng/mL and limit of detection of 0.07 ng/mL. The recoveries for AMOZ ranged from 78.6% to 108.9%, with coefficients of variation below 12%. A good correlation (R 2 = 0.9901) between the immunostrip and LC-MS/MS results in the tissues tested demonstrated the reliability of the immunostrip. These results indicate that proposed immunostrip is suitable for the rapid and quantitative detection of AMOZ residues in edible animal tissues. ARTICLE HISTORY