Validation of HPLC method of analysis of tetracycline residues in eggs andbroiler meat and its application to a feeding trial

HPLC with ion-pairing chromatography and diode-array detection at 355 nm wa s used to determine tetracycline antibiotics in eggs and broiler meat. The analytical methods were optimized and validated. The mean recovery values f or oxytetracycline for eggs and for, tetracycline for breast meat were 76%. The within-day precision ranged from 8.0 to 11.8% for oxytetra-cycline in eggs and from 6.1 to 15.5% for was tetracycline in breast meat. The between -day precision was 4.8% and 5.0% respectively for oxytetracycline in eggs a nd tetracycline in breast meat. The limit of detection and the limit of qua ntitation for oxytetracycline in eggs were 2.2 and 13.0 ng/g respectively. These limits for tetracycline in br east meat were 10.5 and 20.9 ng/g respe ctively. Residue values of tetracycline antibiotics in eggs and broiler mea t were determined after oral administration of medicated feed. Medicated fe ed with 840 mg/kg oxytetracycline was provided to laying hens for seven suc cessive days. Two days after the administration was stopped, the mean oxyte tracycline residue value in the eggs was already lower than the Maximum Res idue Limit (MRL)-level and reached 118 ng/g. Broilers were supplied with me dicated feed containing 480 mg/kg tetracycline for seven successive days. F our days after the administration was stopped, rite mean tetracycline resid ue value in breast meat decreased below the MRL and was 86 ng/g.