Determination of chloramphenicol at ultra-trace levels by high-performance differential pulse polarography: Application to Milk and Meat

High-performance differential pulse polarography (h.p.d.p.p.) is used to determine the antibiotic chloramphenicol. Optimum operating conditions are discussed. Calibration curves are linear from 10 ng ml^-1 to 1 μg ml^-1; the detection limit is about 3 ng ml^-1. Above 1 μg ml^-1, deviations from linearity occur, because of adsorption of chloramphenicol at the mercury electrode. A correction, based on variations in natural drop time, is suggested. Chloramphenicol is readily extracted from milk or minced meat with diethyl ether. The ether is evaporated, and the residue is taken up in acetate buffer pH 4.7 and filtered through a membrane filter. Recoveries from samples fortified at levels of 10–1000 ng ml^-1 are about 60% for milk and 50% for minced meat.