Elimination rule on residues of ciprofloxacin in eggs of Laying hens

A high performance liquid chromatographic method was reported for the quantitative determination of residues of ciprofloxacin in eggs of Laying hens. Ciprofloxacin was extracted from eggs with acetonitrile solution. The extract solution was dried in vacuum condition (45℃) and residues were dissolved in mobile phase. Ciprofloxacin was separated on a Symmetry C18 Column (5 μm,3. 9 mm×150 mm) by 0. 015 mol·L-1 tetrabutyl ammonium bromide/ace-tonitrile (94/6,v/v) and detected at λEX 280 nm, λEM 455 nm by fluorescence detector. Recoveries of ciprofloxacin added to blank eggs at levels of 0. 05, 0. 50, 1. 00 mg·kg-1 were (82. 2±6. 8)%, (84. 5±5. 9)% and (87. 9±4. 7), respectively. This method permitted the minimum detection limit of ciprofloxacin residues in eggs at levels of 0. 01 mg·kg-1. After the Laying hens orally administered successively ciprofloxacin hydrochloride solution of 10. 0 and 20. 0 mg·kg-1 of body weight one time every day for 5 days, respectively, residues of ciprofloxacin in eggs were eliminated slowly. Residues of ciprofloxacin in eggs were lower than 0. 03 mg·kg-1 at 8th-9th withdrawal day. Residues of ciprofloxacin in eggs were all lower than the minimum detection limit (0. 01 mg·kg-1) at 9th-10th withdrawal day. With the increase of ciprofloxacin orally adminietered doses, residues of ciprofloxacin in eggs were increased, accordingly.