Improvement of the tube diffusion test with respect to detection of antibiotic residues and sulphonamides in raw milk

Improvements in detection of tetracycline, sulphonamide, macrolide, rifamycin, trimethoprim and aminoglycoside residues in milk were achieved by addition of either chloramphenicol or trimethoprim, and phenylbutazone to tube diffusion tests utilising Bacillus stearothermophilus var. calidolactis as bacterial test strain. If the modified tube diffusion tests are performed at pH 7 and 8.0 residues of beta-lactams, and of the forementioned groups can be detected below or near their maximum residue levels established for milk.