Determination of cephapirin and ceftiofur residues in bovine milk by liquid chromatography with ultraviolet detection.
A method capable of quantitating cephapirin at a level fo 20 ng/mL and ceftiofur at a level of 50 ng/mL was developed for raw bovine milk. Raw bovine milk is deproteinated with acetonitrile. The supernatant is collected and then acetonitrile is removed under reduced pressure while warming in a water bath at 40 degrees-50 degrees C. The extract is mixed with water and loaded onto a conditioned C18 solid-phase extraction column. Analytes are eluted with acetonitrile, which is removed completely under a stream of nitrogen gas. Analytes are separated from coextractives by gradient elution with an ion-pair mobile phase on a reversed-phase column and are detected by ultraviolet absorbance at 290 nm. Mean recoveries from fortified milk samples ranged from 79 to 87% for cephapirin and from 76 to 86% for ceftiofur, with intralaboratory coefficients of variation ranging of 6-10% and 7-14%, respectively.
U.S. Food and Drug Administration, Center for Veterinary Medicine, Laurel, MD 20708, USA.
P G
PG
Schermerhorn
P S
PS
Chu
M A
MA
Ngoh
D000818:Animals; D002511:Cephalosporins / Q000032:analysis*; D002514:Cephapirin / Q000032:analysis*; D002853:Chromatography, Liquid; D004350:Drug Residues / Q000032:analysis*; D005069:Evaluation Studies as Topic; D005506:Food Contamination; D008892:Milk / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
D002511:Cephalosporins; C053503:ceftiofur; D002514:Cephapirin