Sijun Zhao

Developing and optimizing an immunoaffinity cleanup technique for determination of quinolones from chicken muscle.

An immunoaffinity chromatographic method was developed using an antibody mediated immunosorbent to selectively extract and purify 10 quinolones (marbofloxacin, norfloxacin, ciprofloxacin, lomefloxacin, danofloxacin, enrofloxacin, difloxacin, sarafloxacin, oxolinic acid, and flumequine) in chicken muscle followed by HPLC. The operating conditions of the immunoaffinity chromatography (IAC) column were optimized, and the IAC has been successfully used for the isolation and purification of 10 quinolones from chicken muscle tissue. The optimized immunoaffinity column sample cleanup procedure combined with HPLC coupling to fluorescence detection afforded low limits of detection (0.1 ng g(-1) for danfloxacin and 0.15 ng g(-1) for all other quinolones tested). The method was also applied to determine quinolone residues in commercial muscle samples.

Simultaneous Determination of 7 Quinolones Residues in Animal Muscle Tissues by High Performance Liquid Chromatography

Abstract A rapid and robust multiresidue method was developed for the analysis of seven quinolones (ciprofloxacin, danofloxacin, enrofloxacin, sarafloxacin, difloxacin, oxolinic acid, and flumequine) in animal muscle tissues by HPLC-FLD. The samples were extracted with phosphate aqueous solution and cleaned with HLB-SPE. The analytes were separated using formic acid aqueous solution-acetontrile system as mobile phase with a linear gradient elution program, and determined by programmable fluorescence detection. The linear range was 0.3–1000 μg l −1 with correlation coefficients ( r ) greater than 0.9989. The limits of detection were 0.1–0.3 μg kg −1 , and limits of quantification were 0.3–1.0 μg kg −1 . The mean recoveries for each analyte in chicken and pig muscles ranged from 70.4% to 105.8% with relative standard deviation below 9.3% at 1–100 μg kg −1 fortification levels. The method is convenient, fast, safe, sensitive, and accurate for determining residual quinolones in actual samples.

Design, synthesis and characterization of tracers and development of a fluorescence polarization immunoassay for the rapid detection of ractopamine in pork

In this study, 10 fluorescein-labeled ractopamine (RAC) derivatives (tracers) were synthesized and characterized to develop a rapid fluorescence polarization immunoassay (FPIA) for the detection of RAC in pork, using previously produced RAC polyclonal antibodies. The effect of the tracer structure on the sensitivity of the FPIA was investigated. The specificity of the FPIA was evaluated with 70 β-agonists and β-blockers. The FPIA showed a limit of detection of 0.56 μg kg-1 for RAC in pork, with recoveries ranging from 74.8% to 86.6% in spiked samples. The total analysis time, including sample pretreatment, was less than 1 h. The FPIA was used to screen 150 commercial pork samples for RAC residues and the results were consistent with those of an enzyme-linked immunosorbent assay (ELISA) and ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Our results demonstrate that the FPIA developed here is a rapid, accurate, and sensitive screening method for RAC residues in pork.