Determination of veterinary antibiotics in cow milk using rotating-disk sorptive extraction and liquid chromatography

• Published in: Microchemical journal 2021-03, Vol.162, p.105851, Article 105851
• Main Authors: Castillo-Aguirre, Alver, Cañas, Alejandro, Honda, Luis, Richter, Pablo
• Format: Article
• Language: English
• Subjects: Antimicrobial residues; HPLC-DAD; Rotating-disk sorptive extraction (RDSE); Styrene-divinylbenzene; UPLC-TOF/MS
• ISSN: 0026-265X; 1095-9149
• DOI: 10.1016/j.microc.2020.105851

•Rotating-disk sorptive extraction was applied for the first time in cow milk analysis.•Styrene-DVB is used for the first time in rotating-disk sorptive extraction (RDSE).•An eco-efficient milk analysis was developed for determination of antibiotics.•Antibiotics were determined after extraction by either HPLC-DAD or UPLC-TOF/MS. A novel application of rotating disk sorptive extraction (RDSE), using a styrene-divinylbenzene (S-DVB) sorbent for the extraction of antibiotic residues in milk was developed. The analytes studied were oxytetracycline and its 4-epimer, enrofloxacin, ciprofloxacin, sulfadoxine and trimethoprim. After RDSE, the analytes were determined by performing both high-performance liquid chromatography coupled to diode array detection (HPLC-DAD) and ultrahigh-performance liquid chromatography coupled to ultraspray-electrospray-time of flight-mass spectrometry (UPLC-TOF/MS). By using HPLC-DAD, the absolute recoveries were between 85.5% and 106.4% with relative standard deviations between 3.7% and 9.9%. The obtained limits of quantification (LOQs) were lower than the respective maximum residue levels (MRLs) reported for each analyte, demonstrating that the methodology was applicable for residue depletion studies. UPLC-TOF/MS showed absolute recoveries from 88.5% to 114.1%, with RSDs between 4.3% and 15.4%. The LOQs obtained using UPLC-TOF/MS were also lower than the MRLs for each respective analyte. Compared with other analytical methods previously reported for some of the analytes, the present method is simpler and less expensive and utilizes green chemistry, all while providing comparable figures of merit.