Occurrence of tetracyclines, sulfonamides, sulfamethazine and quinolones in pasteurized milk and UHT milk in China's market

This study examines 94 samples of ultra high temperature (UHT) milk and 26 samples of pasteurized milk from China's top dairy brands (I, II, III, IV), using the ELISA method to assess their contamination with tetracyclines, sulfonamides, sulfamethazine and quinolones. All of the samples were collected from China's market in September 2010. The percentage of UHT milk samples containing detectable levels of tetracyclines, sulfonamides, sulfamethazine and quinolones were 0%, 20.2%, 7.4% and 95.7%, respectively, and 7.7%, 15.4%, 0% and 61.5%, respectively, in pasteurized milk samples. The maximum concentrations of the tetracyclines, sulfonamides, sulfamethazine and quinolones in all liquid milk samples were 47.7 μg kg−1, 20.24 μg kg−1, 14.62 μg kg−1 and 20.49 μg kg−1, respectively. None of the samples exceeded the maximum residue levels (MRLs) set by China, the European Union (EU) and the Codex Alimentarius Commission (CAC). However, because of the high detection rates of some veterinary drug residues in the liquid milk, stringent control measurements for these residues need to remain in effect, in order to guarantee that the milk is safe for people to drink.