SIMULTANEOUS DETERMINATION OF AMPICILLIN AND TETRACYCLINE IN MILK BY USING A STOPPED-FLOW T-FORMAT SPECTROFLUOROMETER/

A fast and simple fluorimetric method is described for the simultaneou s determination of ampicillin and tetracycline in milk by combining th e stopped-flow mixing technique with a T-format spectrofluorimeter. Am picillin determination is based on its hydrolysis with penicillinase a nd reaction with mercuric chloride, while the intramolecular energy tr ansfer from tetracycline to europium ions in the presence of thenoyltr ifluoracetone is used for tetracycline determination The similar excit ation wavelengths of both systems and the separation between the corre sponding emission wavelengths allow the direct determination of both a nalytes by measuring simultaneously the initial rate of the ampicillin system and the equilibrium signal of the tetracycline system. The rel ative standard deviations were lower than 2%. The proposed method was applied to the determination of these antibiotics in different milk sa mples with a recovery of 95.0-103.3% for ampicillin and 93.3-103.3% fo r tetracycline. (C) 1997 Elsevier Science B.V.