Determination of tetracycline residues in dairy milk powder and fresh dairy milk by HPLC method

Abstract Tetracycline residues are group of antibiotics found in animal products such as dairy milk. In this study, the occurrence of tetracycline residues in 45 dairy milk powder and 24 fresh dairy milk samples have been investigated. Tetracycline residue were extracted from milk samples using McIlvine buffer and purified with a solid phase extraction (SPE) C18 column. Residues were detected through HPLC-PDA at wavelengths of 355 and 368 nm. Three forms of tetracyclines were discovered in the 45 milk powder samples, namely; oxytetracycline (31.75 ng/g), tetracycline (28.02 ng/g) and chlortetracycline (10.55 ng/g). The results of 24 fresh dairy milk samples, on the other hand, revealed that only one form of tetracycline (i.e., oxytetracycline) was detected with concentrations ranging from 6.67 to 10.19 ng/g. Although the low incidence and concentration levels of tetracycline contamination in all samples analysed were not alarming, regular monitoring is recommended to avoid any negative public health consequences.