Effect of Cold-Temperature Storage on Stability of Benzylpenicillin Residues in Plasma and Tissues of Food-Producing Animals

Abstract

Abstract A recently developed liquid chromatographic method is used to determine benzylpenicillin residues in incurred tissue and plasma samples from experimental animals stored at freezer temperatures of -20°C and -76°C. It was observed that penicillin- incurred plasma samples stored at -20°C for 2 months were relatively stable, showing a gradual loss of only 10-20% of the residues present at the beginning of the storage period. Loss of penicillin residues from bovine kidney and liver stored at -20°C occurred at a rate that was more rapid than from plasma. Losses in benzylpenicillin concentrations of up to 20% were observed in kidney and liver samples stored at -20C after as little as 10 days of storage. Gluteal muscle samples stored at the same temperature showed almost 50% reduction in benzylpenicillin concentration after only 10 days of storage. However, incurred tissue samples stored at -76°C remained stable. The depletion of benzylpenicillin residues from edible tissues and biological fluids follows a first-order rate law.