Development of a multiplex flow-through immunoaffinity chromatography test for the on-site screening of 14 sulfonamide and 13 quinolone residues in milk.

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 0.5ng/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 (0.13ng/mL) and QNs (0.062ng/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.