The working group "Analyses in Biological Materials" of the Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area developed and verified the presented biomonitoring method. This method allows for the sensitive and precise determination of selected antibiotics (ciprofloxacin, enrofloxacin, lincomycin, penicillin G, and penicillin V) in human urine. Sample preparation includes extracting the analytes by solid‑phase extraction on Oasis HLB cartridges, followed by concentrating the eluates under a stream of nitrogen. The analytes are separated from matrix compounds by liquid chromatography and subsequently detected with tandem mass spectrometry using electrospray ionisation. Quantitative evaluation is carried out via external calibration in urine.

The good precision data and accuracy data show that the method provides reliable and accurate measurement values. Any matrix effects are effectively compensated for by the use of isotope-labelled internal standards. This finding holds similarly true for ciprofloxacin, for which isotope-labelled enrofloxacin was used as internal standard (ISTD). With quantitation limits of 0.1 μg/l for ciprofloxacin, enrofloxacin, and lincomycin as well as 0.3 μg/l for penicillin G and penicillin V, this method is very sensitive and enables the reliable quantitation of occupational exposure to the selected antibiotics.