Determination of Antibiotic Residues in Milk Samples

In this study, antibiotic residues in raw milk and pasteurized milk products sold in Ankara - Turkey investigated. For this purpose; a total of 240 milk samples, which contains 10 raw and 10 pasteurized milk samples per month collected from various markets in Ankara between April 2003 and March 2004 were analyzed in terms of penicillin G, oxytetracycline, gentamicin, streptomycin and neomycin by using TLC (Thin Layer Chromatography)/Bioautographic method, in which Bacillus subtilis ATCC 6633 was used as test microorganism. The minimum detectable concentrations for penicillin G, oxytetracycline, gentamicin, streptomycin and neomycin, as mu g/L were 4, 100, 200, 100 and 1000, respectively and recovery rate as percentage were 75.6, 79.7, 80.9, 84.7 and 73.5, respectively. The concentrations found among pasteurized samples were 150.4 mu g/L oxytetracycline and 33.5 g/L penicillin G and 7688.4 mu g/L of neomycin among raw samples, which are higher than the maximum residue limits in milks accepted in Turkey and European Countries. According to the total number of samples analysed, the ratio of contamination with antibiotics was detected as 1.25%.