Simultaneous determination of 16 macrolide antibiotics and 4 metabolites in milk by using Quick, Easy, Cheap, Effective, Rugged, and Safe extraction (QuEChERS) and high performance liquid chromatography tandem mass spectrometry.

A novel analytical method was developed and validated for simultaneous analysis of 16 macrolide antibiotics and 4 metabolites in milk. A modified quick, easy, cheap, effective, rugged, and safe extraction method (QuEChERS) optimized by response surface methodology (RSM) was used for sample preparation. All the drugs were subsequently separated and detected by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS), using roxithromycin as internal standards for maximum accuracy and precision. The method was validated following the guidelines specified in Commission Decision 2002/657/EC. The recoveries of all the analytes were in the range of 62.27%-115.28%. Most macrolide antibiotics and metabolites could be detected in the concentration of 1-100ng/mL with good correlation coefficient (r2>0.998). The LODs and LOQs of all analytes were in the range of 0.30-0.85μg/kg and 1.1-4.0μg/kg, respectively. The intra-day and inter-day precision were lower than 10% and 15%, respectively. The developed method has been successfully applied to screen these compounds in different milk products.