Determination of kanamycin A, amikacin and tobramycin residues in milk by capillary zone electrophoresis with post-column derivatization and laser-induced fluorescence detection

An analytical method for kanamycin A, amikacin and tobramycin of aminoglycoside (AG) antibiotics in milk samples was proposed using capillary zone electrophoresis (CZE) with post-column derivatization and laser-induced fluorescence detection. A simple and convenient homemade coaxial-gap reactor was adopted in the post-column derivatization of the AGs with 1.0 mmol/L naphthalene-2,3-dicarboxaldehyde and 8.0 mmol/L 2-mercaptoethanol in 35 mmol/L sodium tetraborate buffer (pH 10.0) of 30% (v/v) methanol. 50 mmol/L sodium acetate (pH 5.0) containing 0.5 mmol/L cetyltrimethyl ammonium bromide was used as the separation buffer. The linear calibration concentrations and detection limits were from 2.1 × 10−5 to 5.0 × 10−2 g/L and in the range of 7 × 10−6 to 2 × 10−5 g/L, respectively. The recoveries of the AGs in milk samples were from 81.6 to 93.1% (n = 3).