title: Optimization of a liquid chromatographic method for determination of oxytetracycline, tetracycline, and chlortetracycline in milk.
abstract: A liquid chromatographic (LC) method was developed for the simultaneous identification and quantitation of oxytetracycline, tetracycline, and chlortetracycline in milk. Milk samples (5 mL) were deproteinized by adding 1 mL 1N HCl and 24 mL acetonitrile, and filtering. Dichloromethane and hexane were added to 15 mL filtrate to separate the water layer. The organic layer was washed with 1 mL deionized water, and the combined water layers were diluted to 4 mL. Sample aliquots of 1000 microL were then injected directly and analyzed on an LC system. The sensitivity limit of the method is 5 ppb for each antibiotic; no interferences are present at their retention times. Mean recoveries from milk spiked at 0.01-1 ppm ranged from 87 to 99%, and precision was good.
authors.affiliation: University of Delaware, Department of Food Science, Newark 19716.
authors.forename: C R
authors.initials: CR
authors.lastname: White
authors.forename: W A
authors.initials: WA
authors.lastname: Moats
authors.forename: K L
authors.initials: KL
authors.lastname: Kotula
mesh_terms: D000818:Animals; D002417:Cattle; D002751:Chlortetracycline / Q000032:analysis; D002853:Chromatography, Liquid; D004350:Drug Residues / Q000032:analysis; D008892:Milk / Q000737:chemistry*; D010118:Oxytetracycline / Q000032:analysis; D013056:Spectrophotometry, Ultraviolet; D013752:Tetracycline / Q000032:analysis; D013754:Tetracyclines / Q000032:analysis*
chemical_list: D013754:Tetracyclines; D013752:Tetracycline; D002751:Chlortetracycline; D010118:Oxytetracycline