Results: The limits of detection were 18 μg / kg, 18 μg / kg, 20 μg / kg, 90 μg / kg, 90 μg / kg and 450 μg / kg for gentamycin C1, gentamycin C1a, gentamycin C2+C2a, streptomycin, dihydrostreptomycin and neomycin, respectively.