RECOVERY OF SULFADIMIDINE FROM PIG FEEDS

The poor analytical recovery of sulfadimidine from medicated pig feeds was investigated by high-performance liquid chromatography (HPLC) using unlabelled and C-14-labelled sulfadimidine. In addition, autoradiographic studies of C-14-labelled sulfadimidine binding in feeds was investigated. The HPLC studies using unlabelled sulfadimidine showed that there was an inverse relationship between feed moisture content and sulfadimidine recovery. Feeds with high moisture content (18% m/m) gave lower recoveries than both control feeds (12% m/m) and feeds with low moisture content (5% m/m). Studies using HPLC with both ultraviolet and radioactivity detection showed no evidence for degradation products of sulfadimidine. Autoradiographic studies showed that the non-recovered drug was dispersed throughout the feed. A hypothesis is proposed to account for the poor recoveries.