Analysis of sulfonamide and quinolone antibiotic residues in Korean milk using microbial assays and high performance liquid chromatography

A new protocol to analyse sulfonamides and quinolones from cows’ and goats’ milk was developed. Seven antibiotics, sulfamonomethoxine (SMM), sulfadimethoxine (SDM), sulfamethazine (SMZ), sulfamerazine (SMR), sulfaquinoxaline (SQX), enrofloxacin (ERF), and ciprofloxacin (CIP), were analysed by microbial assays and HPLC. In microbial assays, 21 of 269 samples were screened to have possible antibiotic residues. In HPLC analysis 4 samples were detected to contain SMR (3 samples) and CIP (1 sample). The concentration of SMR in the cows’ milk was 12.2 μg kg−1, which is higher than the LOQ (limit of quantification) and LOD (limit of detection). The levels of SMR and CIP in the other 3 samples were between their LOD and LOQ. Based on this study, we were able to establish an analytical protocol for accurate and robust detection of sulfonamide and quinolone-type antibiotics in milk using two assays.