INVESTIGATION INTO THE THERMAL STABILITY OF NICARBAZIN AND NITROIMIDAZOLES : AN OVERVIEW

Most food containing drug residues is consumed after cooking or processing, yet surveillance for these residues is almost always conducted on raw tissue. This investigation was to establish the effect of cooking on residues associated with the treatment of chickens with (I) the anti-coccidial drug nicarbazin and (U) the nitroimidazole drugs, dimetridazole and ronidazole. Both chicken muscle and egg were studied. Incurred nicarbazin residues in egg, measured using the marker compound (dinitrocarbanilide, DNC), were stable to microwave cooking and residues in chicken muscle were stable to stewing (boiling). Other cooking procedures led to a decrease in amount of DNC by 22 % to 48 % of the total amount of analyte present. Only a small amount (< 2 %) of residue leached with juices which exuded as the food was cooked. In the case of dimetridazole and ronidazole it was found that that these incurred residues were not destroyed by cooking chicken meat, although some of residue leached from the sample with juices which exuded as it cooked. Residue concentrations of these nitroimidazole drugs in egg reduced during cooking by between 14 % and 32 % of their original concentration.