Establishment of magnetic beads-based enzyme immunoassay for detection of chloramphenicol in milk

In this research, magnetic beads-based enzyme immunoassays were investigated for rapid analysis of chloramphenicol (CAP) in milk. To improve sensitivity of CAP determination, two kinds of immunomagnetic separation methods were designed and compared. Magnetic polystyrene microspheres were conjugated with anti-CAP antibody (Method I) or goat-anti-mouse IgG (Method II). The whole determination could be finished in 1.25 h. Both methods showed high sensitivity to CAP in buffer, and obtained an IC50 value of 0.05 ng mL−1 for Method I and 0.4 ng mL−1 for Method II. The methods showed high specificity, only showing a little cross-reaction towards CAP succinate. The two methods were applied to detect CAP in milk. The recovery rates were 80–106% and the coefficients of variation (CVs) were 4.7–15%. The immunomagnetic assay showed promising potential in rapid screening field for CAP analysis. Between the two methods, Method I is more sensitive, and Method II is more suitable for producing a general assay by changing a primary antibody for another analyte.