title: Analytical procedure for the determination of chlortetracycline and 4-epi-chlortetracycline in pig kidneys.
abstract: A liquid chromatography-diode array detection (LC-DAD) procedure has been developed for assaying chlortetracycline (CTC) and its 4-epimer (4-epi-CTC) residues in pig kidneys. The procedure involved extraction with 0.1 M oxalic buffer followed by protein precipitation with trichloroacetic acid. Further solid-phase extraction (SPE) clean-up on a Strata X polymeric cartridge was allowed to obtain an extract suitable for LC analysis. Chromatographic separation was carried out on a C8 analytical column, using isocratic elution with methanol-acetonitrile-0.01 M oxalic acid (15:15:70, v/v/v) at ambient temperature. The flow-rate was 1.2 ml/min and the eluate was analysed at 365 nm. The whole procedure was evaluated according to the requirements of the European Union regulation 2002/657/EC determining specificity, decision limit (CCalpha), detection capacity (CCbeta), trueness, precision and robustness during validation process. The decision limit (CCalpha) was 674.8 microg/kg for CTC and 683.6 microg/kg for 4-epi-CTC. The detection capacity (CCbeta) was 683.6 and 696.3 microg/kg for CTC and 4-epi-CTC, respectively. The recoveries of CTC and 4-epi-CTC from spiked samples at the levels of 300, 600 and 900 microg/kg (0.5 x MRL, 1 x MRL and 1.5 x MRL) were higher than 70%. This method has higher throughput than reported previously extraction method with oxalic acid and acetonitrile used for dechelation and deproteinization.
authors.affiliation: National Veterinary Research Institute, Department of Pharmacology and Toxicology, Pulawy, Poland. aposyn@piwet.pulawy.pl
authors.forename: Andrzej
authors.initials: A
authors.lastname: Posyniak
authors.forename: Kamila
authors.initials: K
authors.lastname: Mitrowska
authors.forename: Jan
authors.initials: J
authors.lastname: Zmudzki
authors.forename: Jolanta
authors.initials: J
authors.lastname: Niedzielska
mesh_terms: D000818:Animals; D002751:Chlortetracycline / Q000032:analysis*; D002853:Chromatography, Liquid / Q000379:methods*; D007668:Kidney / Q000737:chemistry*; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine
chemical_list: D002751:Chlortetracycline