Antibiotics are a class of antimicrobial veterinary drugs widely used to control disease in food producing animals including egg laying chickens. However, antibiotics can migrate into and accumulate in the egg of the chicken being treated.

Eating eggs that contain antibiotic residues could provoke allergic reactions or lead to the development, or dominance of resistant bacterial strains, rendering treatment of human patients with antibiotics ineffective. It is therefore important to develop efficient screening methods for antibiotic residues in eggs intended for human consumption.

Extraction of antibiotic compounds from eggs can be challenging. Eggs are known to contain large amounts of lecithin, which is a mixture of phospholipids, and significant amounts of fats. It is important that the final egg extract be free of these co-extractive substances since they are known to lead to ion suppression and interference during LC/MS/MS analysis.