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TP5 Ecotoxicity and Environmental Chemistry Antibiotics
(284) Biodegradation of chlortetracyclines in manure fertilized soil and identification of degradates by electrospray ion-trap mass spectrometry.
Aga, Diana1, O'Connor, Seamus1, 2, 1 University at Buffalo, Buffalo, NY, United States2
ABSTRACT- The environmental fate, transport, and the ecotoxicological impacts of antibiotics from land-applied manure are largely unknown. A greenhouse experiment was conducted to determine the soil dissipation half-life and identify the degradation products of chlortetracycline using antibiotic-fortified manure. Analysis of the soil extracts showed the presence of undegraded chlortetracycline and transformation products that include isochlortetracycline and anhydrochlortetracycline. Identification and quantification were achieved using positive ion electrospray ionization in an ion-trap mass spectrometer, and comparison of chromatographic retention times with authentic standards. The data dependent MS/MS capabilities of the liquid chromatograph/mass spectrometer instrument facilitated identification of unknown degradates. The disappearance half-life of chlortetracycline was calculated to be 2.4 days, which was derived using the first order decay equation. In the pots planted with corn, only the isochlortetracycline and the chlortetracycline were detected in the soil extracts, while in the non-planted pots anhyrdrochlortetracycline was present in addition to the chlortetracycline isomers. This suggests that the presence of vegetation have an effect on the degradation pathway of chlortetracycline in the soil. The mechanism of soil degradation of chlortetracycline is currently unknown, but the observed effect of corn may have important implications because chlortetracycline isomers and their derivatives have varying degrees of microbial activity.
Key words: antibiotic, chlortetracycline
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