Determination of neomycin residues in eggs and stability of residues after cooking.

The procedure for neomycin residues used a surfactant to improve extraction, a centrifuge step to eliminate solids that interfere with the diffusion of the antibiotic, and a heat treatment to destroy interfering lysozyme activity. The use of Bcillus stearothermophilus and a 65 degree C incubation yielded a rapid assay with a sensitivity of 0.2 microgram neomycin activity/g egg. Frying eggs caused little or no loss of activity, poaching resulted in 25% loss, and soft boiling and hard boiling caused little or no loss of applied activity. Neomycin residues in eggs were quite stable to normal egg preparation procedures.