title: Determination of ciprofloxacin, the major metabolite of enrofloxacin, in milk by isopotential fluorimetry.
abstract: A new method for the determination of ciprofloxacin, the major metabolite of enrofloxacin, for concentrations between 20 and 200 ng/mL by means of matrix isopotential synchronous fluorescence spectrometry and derivative techniques is proposed. This new method is useful for the determination of compounds in samples with unknown background fluorescence, such as ciprofloxacin in whey, without the need of tedious preseparation. The determination was performed in an ethanol/water medium (20% v/v) at pH 4.8, provided by adding a sodium acetate/acetic acid buffer solution. Since enrofloxacin is widely used as an antibacterial agent in veterinary medicine, the method was successfully applied to the determination of its main metabolite in milk. An exhaustive statistical analysis has been developed to all calibration graphs. This treatment includes robust regression such as least median of squares, which also detects outliers and leverage points. The overall least-squares regression has been applied to find the more exact straight line that fits the experimental data. The error propagation has been considered to calculate the detection limit and the repeatability of the method.
authors.affiliation: Department of Analytical Chemistry and Foods Technology, University Castilla-La Mancha, 13071 Ciudad Real, Spain. joseantonio.murillo@uclm.es
authors.forename: J A
authors.initials: JA
authors.lastname: Murillo Pulgarín
authors.forename: A
authors.initials: A
authors.lastname: Alañón Molina
authors.forename: L
authors.initials: L
authors.lastname: Muñoz Fernández
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000032:analysis*; D002939:Ciprofloxacin / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D008892:Milk / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D000890:Anti-Infective Agents; D002939:Ciprofloxacin