Effective separation and simultaneous determination of seven fluoroquinolones by capillary electrophoresis with diode-array detector.

A simple, rapid and accurate method has been developed for effective separation and simultaneous determination of lomefloxacin, gatifloxacin, enoxacin, ciprofloxacin, ofloxacin, enrofloxacin and pefloxacin residues in porcine tissue by capillary electrophoresis with diode-array detector. The separation conditions were investigated and optimized. The sample was extracted with acetonitrile, and a mixture consisted of 25 mM NaH(2)PO(4), 25 mM Na(2)B(4)O(7) and 25 mM H(3)BO(3) (pH 9.0) was used as a running buffer. A linear relationship between concentration and peak area for each compound was obtained in the concentration range of 0.5-100 mg/L with a correlation coefficient greater than 0.9994. For analysis of porcine tissue, the detection limits of lomefloxacin, gatifloxacin, enoxacin, ciprofloxacin, ofloxacin, enrofloxacin and pefloxacin were 0.013, 0.012, 0.023, 0.040, 0.037, 0.035 and 0.034 mg/kg, respectively. The recoveries are in the range of 72-93%. The intra-day precision is less than 5%, and the inter-day precision is less than 10%. The proposed method has high resolution, speed and the extremely small sample volume required. It can permit to confirm the presence of the studied seven fluoroquinolones in porcine tissue at the required maximum residue limit (MRL) level.