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 x 10(-5) to 5.0 x 10(-2)g/L and in the range of 7 x 10(-6) to 2 x 10(-5)g/L, respectively. The recoveries of the AGs in milk samples were from 81.6 to 93.1% (n=3).