A Novel Approach for Single-Step Analyte Fractionation of Raw Milk Prior to Antibiotic Residue Trace Analysis as an Alternative to QuEchERS-Based Extraction

Abstract

Background Antibiotic residues in milk are a well-known hazard in the dairy food chain. Detection methods for these residues, such as non-specific microbiological inhibitor tests or group-specific receptor tests, respectively, are relatively inexpensive, easy to use and widely applied to ensure food safety. In contrast, specific detection by liquid chromatography tandem mass spectrometry (LC-MS/MS) - although a critical, complimentary method to confirm the results of non-specific testing—is relatively costly, time consuming and laborious. Furthermore, sample processing before LC-MS/MS analysis requires unique preparation procedures for different groups of antibiotic compounds. Objective To simplify and speed up specific antibiotic residue detection, a low-cost, passive and single-step method to fractionate analytes in raw milk was developed. Methods Untreated raw milk was fractionated into its water and fat/protein phases using a FraMiTrACR® AB fractionation unit. The water fraction was then analyzed by LC-MS/MS. The analyte fractionation method was evaluated against a QuEChERS based method for sample preparation. Results Our method allows qualitative and quantitative detection of substances from the Penicillin, Cephalosporin, Macrolide, Lincosamide, Sulfonamide, Tetracycline and Fluoroquinolone groups of antibiotics. Detection limits are below the legally prescribed maximum residue levels, allowing reliable, specific and rapid validation of a positive result in non-specific microbiological inhibitor tests. Conclusion Analyte fractionation by FraMiTrACR® AB is a faster alternative to QuEChERS based sample preparation for the detection of antibiotic substances in milk. Highlight This method describes a low-cost, environmentally friendly, passive and single-step milk analyte fractionation. As an alternative to QuEChERS based preparation, this fractionation method simplifies and speeds up the process for specific antibiotic residue detection.