Electrophoretic methods for screening for antibiotics in animal feeds.

A new system for screening antibiotics in animal feeds involves washing antibiotic-containing animal feeds with a series of organic solvents to eliminate interferences and partially separate the antibiotics. Antibiotics are then determined by using paper electrophoresis and thin-layer bioautography. This approach enables the separation and qualitative identification of 17 antibiotics currently used in animal feeds and provides the ability to detect low-level cross-contamination.