ASSAY FOR CEPHAPIRIN AND AMPICILLIN IN RAW-MILK BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY-INTEGRATED PULSED AMPEROMETRIC DETECTION

The FDA has issued guidelines governing the use of antibiotics in catt le and routinely tests for the presence of antibiotics in milk. Unfort unately, these compounds are often difficult to detect by direct metho ds because they often lack a chromophore or fluorophore. Integrated pu lsed amperometric detection (IPAD) following reversed-phase liquid chr omatography is well-suited for this analysis because it is selective, sensitive, and direct; i.e., derivatization is not required. This work involves the development of a simple, rapid assay for the determinati on of beta-lactam antibiotic residues in milli using HPLC-IPAD, specif ically, ampicillin and cephapirin. Since the analytes studied here are detectable by UV detection, a comparison between IPAD and UV detectio n will be made. Sample preparation schemes that involve the extraction of antibiotics of interest from the milk matrix and subsequent cleanu p are an important aspect of this project. These procedures will be di scussed in detail. In addition, analytical figures of merit and IPAD w ave form optimization will be addressed.