Identification and measurement of beta-lactam antibiotic residues in milk: integration of screening kits with liquid chromatography.
A procedure for identifying and quantitating violative beta-lactams in milk is described. This procedure integrates beta-lactam residue detection kits with the multiresidue automated liquid chromatographic (LC) cleanup method developed in our laboratory. Spiked milk was deproteinized, extracted, and subjected to reversed-phase LC using a gradient program that concentrated the beta-lactams. Amoxicillin, ampicillin, cephapirin, ceftiofur, cloxacillin, and penicillin G were, thus, separated into 5 fractions that were subsequently tested for activity by using 4 kits. beta-lactams in the positive fractions were quantitated by analytical LC methods developed in our laboratory. The LC cleanup method separated beta-lactam antibiotics from each other and from interferences in the matrix and also concentrated the antibiotics, thus increasing the sensitivity of the kits to the beta-lactam antibiotics. The procedure facilitated the task of identifying and measuring the beta-lactam antibiotics that may be present in milk samples.
Harik-Khan
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U.S. Department of Agriculture, Meat Science Research Laboratory, Beltsville, MD 20705, USA.
Moats
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WA
D000818:Animals; D000900:Anti-Bacterial Agents / Q000032:analysis*; D002853:Chromatography, Liquid; D004350:Drug Residues / Q000032:analysis; D005069:Evaluation Studies as Topic; D005506:Food Contamination; D008892:Milk / Q000737:chemistry*; D011933:Reagent Kits, Diagnostic; D047090:beta-Lactams
D000900:Anti-Bacterial Agents; D011933:Reagent Kits, Diagnostic; D047090:beta-Lactams