Determination of penicillin G and cloxacillin residues in beef and pork tissue by high-performance liquid chromatography.
Tissues were homogenized and then deproteinized with acetonitrile. The acetonitrile extract was partitioned between dichloromethane and pH 2.2 buffer and then extracted with pH 7 buffer. After addition of ammonium sulfate to the aqueous solution, it was mixed with acetonitrile. The acetonitrile extract was separated and evaporated, and the residue was taken up in water. The aqueous solution was analyzed by high-performance liquid chromatography (HPLC) on a C18, 10-microns particle size, reversed-phase column using gradient elution with 0.01 M orthophosphoric acid-acetonitrile (from 80:20 to 40:60 in 20 min) at a flow-rate of 1 ml/min and UV absorbance detection at 220 nm. Recoveries were generally greater than 90% with all tissues. Data on incurred residues from a treated cow showed recoveries of penicillin which were frequently several times higher by HPLC than by bioassay. Sensitivity limits in muscle were about 0.05 ppm for both penicillin G and cloxacillin, but higher in liver and kidney because of interferences. The method is suitable for other monobasic penicillins but not for dibasic or amphoteric penicillins.
D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003023:Cloxacillin / Q000032:analysis*; D008460:Meat / Q000032:analysis*; D010400:Penicillin G / Q000032:analysis*; D013552:Swine
D003023:Cloxacillin; D010400:Penicillin G