Determination of four fluoroquinolones in milk by on-line immunoaffinity capture coupled with reversed-phase liquid chromatography

An automated, on-line immunoaffinity extraction method was developed for th e analysis of 4 fluoroquinolones in milk: ciprofloxacin, difloxacin, enrofl oxacin, and sarafloxacin, This method involves analyte extraction using an immunoaffinity capture column containing anti-fluoroquinolone antibodies co upled on-line with reversed-phase column chromatography. Liquid chromatogra phic analyses were performed by isocratic elution using a mobile phase of 2 % acetic acid-acetonitrile (85 + 15) and an Inertsil phenyl column with flu orescence detection at excitation and emission wavelengths of 278 and 444 n m, respectively, No significant interferences from the sample matrix were o bserved, indicating good selectivity with the immunoaffinity column, Recove ries from fortified raw milk samples (5-50 ppb of each fluoroquinolone) ran ged from 72 to 90%, with standard deviations of less than or equal to 8%.