A highly efficient and economic method for the simultaneous determination of six common antibiotics (two tetracyclines, two quinolones, and two sulfonamides) in chicken manure was developed by using solid-phase extraction and high performance liquid chromatography (SPE-HPLC). The samples were extracted by using a mixture of the EDTA-McIlvaine buffer and a mixed organic extractant (methanol-acetonitrile-acetone, 2:2:1, v/v/v), cleaned by a hydrophile-lipophile balance (HLB) cartridge, eluted by methanol-dichloromethane (7:3, v/v), and separated by HPLC with an acetonitrile-0.7% (v/v) H3PO4 aqueous solution as the mobile phase. The detection wavelength and temperature of the chromatographic column were 270 nm and 32℃, respectively. All antibiotics showed great linear relationships in the range of 0.5-100 mg/L; the correlation coefficients (r2) of the standard curves were between 0.9999 and 1; the recoveries of antibiotics were between 70.0% and 116.3%; and the relative standard deviations were between 1.2% and 16.6%. The limits of detection were 1.3-6.7 μg/kg; and the limits of quantity were 3.5-9.2 μg/kg. This method was used to detect antibiotics in chicken manure from a hennery in Fushun, Liaoning Province. The contents of norfloxacin and enrofloxacin (quinolones) were from not detected to 9.23 mg/kg and 1.57-7.69 mg/kg, respectively, that of sulfamethazine (sulfonamides) were 2.02-13.05 mg/kg, while sulfamethoxazole, oxytetracycline, and tetracycline were undetectable.
