Development of a highly sensitive and specific monoclonal antibody-based enzyme-linked immunosorbent assay for determination of doxycycline in chicken muscle, liver and egg

A modified indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) method was developed using a highly sensitive and specific monoclonal antibody (McAb) to determine doxycycline (DC) residues in chicken tissues and egg. The McAb against DC was produced by hybridoma technique and a modified ic-ELISA was characterised in terms of sensitivity, specificity, precision and accuracy. At optimal experimental conditions, the standard curve was constructed at concentrations ranged from 0.01 to 100 ng/ml. The IC50 value was 1.32 ± 0.18 ng/ml. The limit of detection was 0.14 ± 0.02 ng/g. The recoveries of DC from spiked chicken liver, muscle, and egg at levels of 50–600 ng/g were 84.6–85.5%, 88.2–89.1%, and 84.4–89.3%, respectively. The coefficient variations (CVs) were 5.1–9.3%, 3.7–11.3%, and 4.7–9.8%, respectively. Linear regression analysis showed good correlation, with r2 values 0.9909 for chicken liver and 0.9916 for chicken muscle.