Contamination of Animal Feed with Undeclared Tetracyclines-Confirmatory Analysis by Liquid Chromatography-Mass Spectrometry after Microbiological Plate Test.

The presence of tetracycline (TC) antibiotics was determined in animal feed that had been previously screened with a microbiological plate test. Feed samples were screened by a microbiological plate test on a pH 6.0 culture medium seeded with ATCC 11778 able to pre-reveal the presence of tetracyclines.