Analytical Strategy for the Regulatory Control of Residues of Chloramphenicol in Meat: Preliminary Studies in Milk

An analytical strategy Is described for the regulatory control of residues of the veterinary drug chloramphenicol (CAP) In meat. Screening is performed directly in meat by a simple immunochemical card test with a limit of detection of about 2 μg/kg. Statistical evaluation of a collaborative study involving 13 laboratories showed that at CAP concentrations exceeding 8 μg/kg, no false negatives are found (N = 554). In positive samples, CAP Is quantltated with a routinely applicable, collaboratively tested column liquid chromatographic method with a limit of detection of about 1 μg/kg. At concentrations exceeding 10 μg/kg, the Identity of CAP Is established by Its UV spectrum obtained by using diode-array UV/VIS detection. A further confirmation can be obtained by the combination of gas chromatography/ mass selective detection In the electron Impact mode. Using 2 diagnostic Ions (m/z 225 and 208), the limit of identification Is about 5 μg/kg. The combination of the different analytical principles ensures reliable quantitation and Identification of CAP in positive samples, as established experimentally in Incurred samples and spiked samples (n > 100), and theoretically by the estimation of the uncertainty factor. The proposed set-up makes a regulatory program possible in which screening can be performed In a simple laboratory environment, followed by quantitation and Identification under more sophisticated conditions. Preliminary experiments Indicate that the analytical strategy Is also applicable to the control of CAP in milk. Application of mass spectrometry with negative chemical ionization permits the confirmation of CAP concentrations as low as 0.2 μg/L.