Method Improvement for Analysis of Enrofloxacin and Ciprofloxacin in Chicken Meat: Application of In-Sample Addition of Trace Ethylenediaminetetraacetic Acid to Isotope Dilution Ultra-Performance Liquid Chromatography–Mass Spectrometry

A method for analyzing fluoroquinolone antibiotics, viz. enrofloxacin and ciprofloxacin, in chicken meat has been developed with the aim of reducing the total analysis time. Certified reference materials (CRMs) for the chicken meat powder, i.e. KRISS CRM 108-03-003 and KRISS CRM 108-03-004, were used for method development. Isotope dilution ultra-performance liquid chromatography–mass spectrometry (ID-UPLC-MS) was employed for sample analysis. The liquid chromatography (LC) conditions were optimized with an “in-sample addition” method using a trace amount of ethylenediaminetetraacetic acid (EDTA), in which EDTA was not added to the mobile phase but to the sample alone. The optimal EDTA amount was determined, and its influence on the separation of the target analyte was investigated. After the feasibility of the “in sample-addition” approach was confirmed, we attempted to improve the previously established sample pretreatment method by varying the conditions for liquid–liquid extraction and solid phase extraction. The developed method was validated using raw chicken meat for recovery evaluation. The “in-sample addition” method afforded highly improved peak shapes without adversely affecting the LC/MS method performance, and the quantification values of enrofloxacin and ciprofloxacin corresponded well with those obtained using the established method. Consequently, the total analysis time for the determination of enrofloxacin and ciprofloxacin in chicken meat CRM could be reduced by simplifying the sample pretreatment procedure. The developed method delivered better reliability compared to the previously established analytical method. The method will be used for stability monitoring of the chicken meat CRM and the development of other meat CRMs for fluoroquinolone analysis and improved food safety applications.