Stability of penicillin antibiotic residues in meat during storage - Ampicillin

Incurred samples from a pig treated with ampicillin, one of the most import ant penicillin antibiotic drugs used food-producing animal treatments, were analyzed at the residue level of the drug in muscle tissue (approximate to 100 mu g kg(-1)) during their freezing storage and using three different t echniques: quantitative microbiological assay, HPLC-UV and LC-MS. Two param eters have been specifically monitored: storage temperature (20 and -75 deg rees C) and storage packaging (ground meat or bulk meat). No significant de crease was observed during the first 3 months of storage monitoring at -20 and -75 degrees C. On the contrary, the sample preparation significantly af fected the drug concentration in muscle from the very beginning of the stor age. Grinding the meat before storage allowed to keep the drug near the hig her level of concentration (approximate to 100 mu g kg(-1)) when bulk meat stored frozen systematically led to a decreased value (approximate to 75 mu g kg(-1)). After 8 months of storage at -20 degrees C, a significant decre ase arose and was never observed at -75 degrees C. All the results were sim ilarly obtained with the three different techniques used simultaneously, wh ich allows to indicate a good correlation between the techniques. (C) 2000 Elsevier Science B.V. All rights reserved.