Micelle enhanced and terbium sensitized spectrofluorimetric determination of danofloxacin in milk using molecularly imprinted solid phase extraction

An efficient molecularly imprinted solid phase extraction (MISPE)-spectrofluorimetric method was developed to sensitively determine danofloxacin (DAN) in milk samples. Solid phase extraction procedure using MISPE cartridges was first performed on milk samples and then spectrofluorimetric determination was done at 546 nm using an excitation wavelength of 285 nm in presence of terbium and sodium dodecyl benzene sulfonate (SDBS). It was found that SDBS significantly enhanced the fluorescence intensity of the DAN–Tb3+ complex. Various factors affecting the fluorescence intensity of DAN–Tb3+–SDBS system were studied and conditions were optimized. The enhanced fluorescence intensity of the system (ΔF) showed a good linear relationship with the concentration of DAN over the range of 8.4 × 10−9–3.4 × 10−7 mol L−1 with a correlation coefficient of 0.9996. The detection limit was determined as 2.0 × 10−9 mol L−1 and the limit of quantification was determined as 6.5 × 10−9 mol L−1. The MISPE-spectrofluorimetric procedure was successfully applied to the determination of DAN in milk samples. The method is simple, rapid, sensitive and allows interference free determination of DAN in complex fluorescent matrices like milk. The method can be used to determine whether the DAN residues in milk exceed MRLs or not.

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► A terbium based spectrofluorimetric method is developed for determination of danofloxacin.
► Sample preparation is done using molecularly imprinted solid phase extraction cartridges.
► The method allows interference free determination of danofloxacin in complex matrices.
► Danofloxacin residues in milk around MRL values can be determined by this method.