A simple, low-cost, and reusable optofluidic platform was developed for direct and ultrasensitive immunoassay of AFM₁.

Effect of organic solvents on interaction of antibody-antigen in heterogeneous and homogeneous solutions was evaluated.

AFM₁ can be directly quantified by the proposed platform even if the samples contain a certain organic solvent.

This method provides the LOD of 5 ng/L for AFM₁ in dairy products.

This method provides a tool for the rapid, accurate, and reliable detection of AFM₁ with a simple sample pretreatment.