Magnetic microsphere based droplet microarray for high-throughput screening of multiple chemical residues in milk

In this paper, aflatoxin M₁, sulfamethoxazole, ciprofloxacin, and lincomycin were selected as model analytes, and we introduced a novel quadplex droplet microarray format for simultaneous screening of multiple chemical residues in milk samples. The droplet microarray relied on micro-volume shallow-well microplate combined with microspheres-based suspension array. In the new established droplet microarrays, the consumption of samples and immunoreagents was reduced by 80 %. While, the antigen-antibody binding process can be completed in as little as 5 min. The limit of detection was evaluated to be 0.023 μg/kg for aflatoxin M₁, 5.68 μg/kg for sulfamethoxazole, 0.85 μg/kg for ciprofloxacin, and 2.65 μg/kg for lincomycin. The recoveries of the target analytes from spiked milk were 79.7 %-102.6 %, with the coefficients of variation not larger than 10.6 %. The newly developed droplet microarray has been demonstrated with good validity and sensitivity by comparing it with the conventional immunoassays and instrumental methods.