Magnetic molecularly imprinted microspheres and carbon dots based semi-homogeneous fluorescence method for detection of roxarsone and arsanilic acid in animal feeds

Roxarsone and arsanilic acid are all organoarsenic compounds, and they are usually used as feed additives. However, their residues in foods of animal origin and their metabolites distributing into the environment are the public concerns. The inspection of their appearances in animal feeds can avoid the above problems. In this study, a type of magnetic molecularly imprinted microsphere was synthesized that was combined with a carbon-dots labeled fluorescent tracer to develop a semi-homogeneous fluorescence method for determination of the two drugs in animal feeds. Results showed this method contained only one step (sample-loading), the limits of detection for roxarsone and arsanilic acid were 0.02 and 0.12 mg/kg respectively, and the magnetic microsphere could be reused for 4 times. In addition, the method sensitivity when using carbon-dots labeled fluorescent tracer was higher than that when using fluorescein isothiocyanate labeled fluorescent tracer. This method exhibited better performances than the previous immunoassays and molecularly imprinted polymer-based method for determination of the two analytes. So this method could be used as a simple tool for screening of roxarsone and arsanilic acid in animal feeds.