PARENT SESSION
1F Human and Veterinary drugs in the environment
9:00 AM to 7:00 PM, Monday, 07 May 2001

(M/EH059) Detection of tetracyclines in the environment by HPLC directly coupled with microbiological assay and MS-MS.

Sczesny, Silke¹, Hamscher, Gerd¹, Höper, Heinrich², Nau, Heinz¹, ^{1 2}

ABSTRACT- Detection of tetracyclines in the environment by HPLC directly coupled with microbiological assay and MS-MS. Sczesny S¹, Hamscher G¹, Höper H², and Nau H¹. ¹Department of Food Toxicology, School of Veterinary Medicine, Hannover. ¹Geological Survey of Lower Saxony, Bremen, Germany. There is growing interest about the exposure, the fate and the effects of veterinary drugs in the environment. Recently we found tetracycline (TC) and chlortetracycline (CTC) residues in farmland fertilized with slurry [Hamscher et al., Dtsche. tierärztl. Wschr.8, 332-334, 2000]. Actually we investigated with a newly developed method dried slurry, which was picked up from the topsoil of farmland fertilized with pig slurry. After sample cleanup and HPLC, 90% of the eluate was subjected in line to a microbiological assay and 10% were used for LC-ESI-MS-MS. In order to perform the microbiological assay the HPLC eluent was fractionated into 96-well microplates. After lyophilisation of the eluent a tetracycline sensitive Staphylococcus aureus in culture broth was added to the microplates and incubated at 37°C. 14h later the bacterial growth was measured with a microplate photometer at 595 nm. The maximum concentration of the microbiological active substances found were 132 g/kg TC and 1000 g/kg CTC. The biologically less active 4 - epimer of CTC could also be detected with this assay because of its epimerisation back to CTC during incubation. With LC-ESI-MS-MS we found additionally the 4-epimer TC, and the biologically inactive iso-CTC and epi-iso - CTC as well as anhydro -CTC. We conclude that acute problems with tetracyclines in the environment may arise, especially from the viewpoint of antibiotic resistance, when animal slurry is not sufficiently ploughed into the soil. The dried slurry may be picked up by birds or other animals and the liberation of active compounds from soil compartments may occur in the acidic environment of the GI-tract.

Key words: microbiological assay, tandem mass spectrometry, tetracyclines, soil