title: Procedure for detecting and confirming pentobarbital residues in dog food by gas chromatography/mass spectrometry.
abstract: The method described detects and confirms presence of pentobarbital residues in dry, extruded feeds at concentrations of 5-20 ppb. Dried feed is ground to a uniform powder and shaken overnight in methanol. A portion of the methanolic extract is evaporated, and the residue is reconstituted in phosphate-buffered saline. The aqueous extract is cleaned with a solid-phase extraction cartridge designed to extract barbiturate residues from biological matrixes. Dimethyl sulfoxide, tetramethylammonium hydroxide, and iodomethane are added to derivatize pentobarbital, 1,3-Dimethyl-pentobarbital is then acidified with dilute hydrochloric acid and extracted with isooctane. The organic layer is transferred and evaporated under a stream of nitrogen. The residue is reconstituted in a small volume of ethyl acetate for analysis by gas chromatography/mass spectrometry. The limit of detection is approximately 0.7 ppb. The method was validated with pentobarbital-fortified feed samples containing high concentrations of meat and bone meal.
authors.affiliation: U.S. Food and Drug Administration, Center for Veterinary Medicine, Laurel, MD 20708, USA.
authors.forename: L A
authors.initials: LA
authors.lastname: Adam
authors.forename: V B
authors.initials: VB
authors.lastname: Reeves
mesh_terms: D000478:Alkylation; D000821:Animal Feed / Q000032:analysis*; D000818:Animals; D004285:Dogs; D004350:Drug Residues / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry; D006993:Hypnotics and Sedatives / Q000032:analysis*; D010424:Pentobarbital / Q000032:analysis*; D015203:Reproducibility of Results; D012996:Solutions
chemical_list: D006993:Hypnotics and Sedatives; D012996:Solutions; D010424:Pentobarbital