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In this paper, a rapid and sensitive multiplex flow-through immunoaffinity chromatography test (FTIACT) was developed for the on-site screening of 14 sulfonamide and 13 quinolone residues in milk. The developed FTIACT method combines the purification, preconcentration and immunochemical detection of multiple antibiotics on the sepharose gel test layers. The use of liposome-encapsulated quantum dots (LQDs) with the FTIACT method exhibited the best results, with limits of detection (LODs) of 1 and 0.5 ng/mL for the sulfonamides (SAs) and quinolones (QNs), respectively, through qualitative analysis (visual detection by the naked eye). In order to achieve low detection limit, the color intensity of the images were converted into relative optical density values to enable a quantitative evaluation. Quantitative analysis of the samples enabled the detection of SAs (0.13 ng/mL) and QNs (0.062 ng/mL) in spiked milk samples. The FTIACT described in this work shows promise as a multiplex immunoassay for the qualitative and quantitative screening of multiple chemical residues in milk. [ABSTRACT FROM AUTHOR]

Abstract A reliable ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method was developed for the simultaneous identification and quantification of 22 β-agonist residues in swine muscle and liver tissues. A special focus was given to sample the pretreatment procedures and was crucial for an accurate and reliable analytical method. With regard to the high complexity of food matrices, the extraction solvent, time, and temperature, as well as clean-up cartridges, were optimized to improve the extraction efficiency and reduce matrix effects. The UHPLC-MS/MS method was further validated by determining the linearity (R2 ≥ 0.9900), sensitivity (limit of detection varying from 0.05 μg/kg to 0.8 μg/kg, limit of quantitation ranging from 0.2 μg/kg to 2.5 μg/kg), recovery (ranging from 76.4 to 111.7%) and precision (≤22.9%) in swine muscle and liver tissues. The UHPLC-MS/MS method was proven to be suitable for both screening and the confirmatory determination of 22 β-agonist residues in swine muscle and liver tissues. [ABSTRACT FROM AUTHOR]

In this study, new clindamycin (CLIN) artificial antigens were prepared and used to produce broad-specificity monoclonal antibodies. Based on the as-produced mAbs, a heterologous ELISA was developed to detect CLIN and lincomycin (LIN) residues in edible animal tissues. The IC 50 values of the developed assay were 0.3 ng/mL (CLIN) and 1.2 ng/mL (LIN) in buffer, respectively. The detection limits were estimated to be 1.8 μg/kg (CLIN) and 6.8 μg/kg (LIN) in bovine, chicken, porcine and fish muscles. In the spike and recovery tests, the mean recovery rate ranged from 76% to 112% at different spiked levels, and the intra −/inter-assay coefficients of variation were in the range of 7.1% to 13.2%. This method was verified using LC − MS/MS with a correlation coefficient > 0.97. The developed ELISA is therefore well suited for simultaneous determination of CLIN and LIN residues in bovine, chicken, porcine and fish muscles. [ABSTRACT FROM AUTHOR]