Confirmation of phenylbutazone residues in bovine kidney by liquid chromatography/mass spectrometry.
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.
Clark
Susan B
SB
sclark1@ora.fda.gov
Turnipseed
Sherri B
SB
Nandrea
Gene J
GJ
Madson
Mark R
MR
Hurlbut
Jeffrey A
JA
Sofos
John N
JN
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
D000894:Anti-Inflammatory Agents, Non-Steroidal; D007202:Indicators and Reagents; D010653:Phenylbutazone