Sulfonamide residues in commercial layer chicken eggs in Dar-es-Salaam, Tanzania

Sulfonamides are used in poultry production for prevention and treatment of bacterial and protozoal infections. Misuse of these drugs or poor adherence to drug withdrawal period has resulted in reports of unacceptable residue levels in poultry products from many developing countries. This study investigated sulphonamide residues in chicken eggs sold in Dar-es-Salaam, which is the biggest consumer of poultry pruducts in Tanzania. A total of 96 eggs randomly collected from commercial layer chicken production farms in Dar-es-Salaam were analysed for sulfadiazine and sulfamethazine residues by use of High Performance Liquid Chromatography (HPLC). Extraction of residues from eggs was executed using liquid-liquid extraction in acetonitrile. The quantification of residues was achieved by using the UV detector at 265 nm and C18 column; (25 cm x 4.6 mm x12 μm). The mobile phase composed of 10 mM potassium di-hydrogen phosphate buffer. Results indicated that all analysed samples contained sulfadiazine while 59.4% contained sulfamethazine residues. Out of the 96 positive samples which were positive for sulfadiazine residues, 28 (29.2%) contained residues above the maximum residues limit (MRL). However, sulfamethazine residues detected in 54% of eggs were all below the MRL. These finding suggest that egg consumers in Dar-es-Salaam are at a risk of exposure to sulfonamide residues.