RESUMO
Carbadox, an antimicrobial agent, and pyrantel tartrate, an anthelmintic, are feed additives that are often used in combination in the United States. The current AOAC methods for these analytes are spectrophotometric, using standard addition techniques. These methods are labor-intensive and prone to variability as well as matrix interferences. Published methods for both analytes that use high-performance liquid chromatography were evaluated and a test method was developed. The method uses a water prewetting step to enhance extraction of pyrantel followed by extraction with acetonitrile-ethanol (50 + 50). Sample extracts are filtered through a glass fiber filter and purified using alumina solid-phase extraction columns. Chromatography is performed on a C18 column with a gradient mobile phase of dibutylamine acetate and acetonitrile. The data show that both analytes exhibit acceptable peak shape when a C18 column that is both acid- and base-deactivated is used. Linearity has been established and initial recovery studies on medicated swine feeds are promising.
