title: Confirmation of phenylbutazone residues in bovine kidney by liquid chromatography/mass spectrometry.
abstract: A confirmatory method is described for phenylbutazone (PB) residues in bovine kidney tissue. Ground kidney tissue is diluted with water, and the mixture is made basic with 25% ammonium hydroxide in water; the lipids are extracted with ethyl and petroleum ethers. The ether layer is discarded, and the tissue is acidified with 6N HCl. PB residues are extracted with tetrahydrofuranhexane (1 + 4). The extract is passed through a silica solid-phase extraction column, and the eluate is evaporated to dryness. The residue is dissolved in acidified acetonitrile-water-acetic acid (50 + 49.4 + 0.6). A single quadrupole mass spectrometer coupled to a liquid chromatograph with an electrospray interface is used to confirm the identity of the PB residues in the kidney extract. Negative-ion detection with selected-ion monitoring of 4 ions is used. Sets of control and fortified-control kidney tissues (at 50, 100, and 200 ppb PB) and several kidney tissue field samples were analyzed for method validation. The method was tested further during the course of a survey to determine the incidence of PB residues in bovine kidney samples obtained from slaughterhouses across the country. In addition, the method was tested for use with an ion-trap mass spectrometer coupled to a liquid chromatograph, which allowed confirmation of PB at lower levels (5-10 ppb) in kidney tissue.
authors.affiliation: sclark1@ora.fda.gov
authors.forename: Susan B
authors.initials: SB
authors.lastname: Clark
authors.forename: Sherri B
authors.initials: SB
authors.lastname: Turnipseed
authors.forename: Gene J
authors.initials: GJ
authors.lastname: Nandrea
authors.forename: Mark R
authors.initials: MR
authors.lastname: Madson
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Hurlbut
authors.forename: John N
authors.initials: JN
authors.lastname: Sofos
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000032:analysis*; D002417:Cattle; D002853:Chromatography, Liquid; D004350:Drug Residues / Q000032:analysis; D007202:Indicators and Reagents; D007668:Kidney / Q000737:chemistry*; D013058:Mass Spectrometry; D010653:Phenylbutazone / Q000032:analysis*; D012015:Reference Standards; D015203:Reproducibility of Results
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D007202:Indicators and Reagents; D010653:Phenylbutazone