Determination of Danofloxacin and Marbofloxacin in Milk Samples by Micellar Liquid Chromatography with Fluorescence Detection

摘要

A simple,rapid,and sensitive analytical method has been developed for the determination of two fluoroquinolones,danofloxacin and marbofloxacin,in bovine milk samples.Separation and quantification were performed by micellar liquid chrom- atography with fluorescence detection (MLC-FD),using sodium dodecyl sulfate (SDS) as a surfactant.The influence of the principal factors,namely,the micelle concentration,the amount of organic modifier,tail-reducing agents,the pH,and the temperature were studied.The suitable condition was found to be 75 mM SDS-10 mM phosphate buffer-18 mM tetrabutylammonium bromide/3% (v/v) 1-propanol at pH 3.0 for the separation of marbofloxacin,danofloxacin,and tosuflox- acin (internal standard) in about 20 min.The linear concentration range of application was 1.8-30.0 ng centre dot mL-1 for danofloxacin and 16-120 ng centre dot mL-1 for marbofloxacin,and the relative standard deviation ranged between 4.9 and 2.7%.The limit of detection found for danofloxacin was 0.5 ng centre dot mL-1 and 5 ng centre dot mL-1 for marbofloxacin.These values were lower than the maximum residue limits (MRLs) established by the European Union for these compounds in bovine milk.It was applied to check the eventual existence of these compounds above these limits on com- mercial milk samples.The validation method was completed with spiked milk samples.Recovery levels obtained were 90.3-108.2%.