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IP10 Emerging Issues in Analytical Chemistry
(IP085) Quantification of sulfonamides in natural waters using fully automated online solid phase extraction liquid chromatography tandem mass spectrometry.
Stoob, K1, Goetz, C2, Ruff, M1, Singer, H P1, Mueller, S R3, 1 Swiss Federal Institute for Environmental Science and Technology (EAWAG), Duebendorf, Switzerland2 Swiss Federal Institute of Technology (ETH), Zuerich, Switzerland3 Swiss Agency for the Environment, Forests and Landscape (SAEFL), Bern, Switzerland
ABSTRACT- For field studies dealing with the fate and behaviour of sulfonamide antibiotics in the environment fast and reliable quantification methods are needed to analyse the large quantities of water samples necessary to assess their export behaviour from agricultural fields. For these purposes, a new method was developed by coupling online an automated solid phase extraction (SPE) with a liquid chromatography tandem mass spectrometer (LC-MS/MS). The online coupling allows the easy, fast and reliable determination of sulfonamide antibiotics and metabolites in environmental water samples at the low ng/L level. Reliable results where achieved by using isotope labelled sulfonamides as internal standards for almost each analyte. Due to the identical behaviour of analytes and internal standards during enrichment and measurement, problems with variable extraction recoveries and ion suppression effects in the MS were eliminated. The online SPE coupling was developed with commercial available standard equipment. A PAL-Autosampler equipped with three additional switching valves and a diluter was used for automated enrichment (sample volumes up to 20 mL) and for the elution from the OASIS HLB enrichment column. The elution was performed with a 1:1 mixture of methanol and water containing 0.1% formic acid (pH 2.4). By pumping a 10 mM ammonia acetate (pH 7) solution to the eluted fraction before the separation column, the methanol concentration was decreased to less then 5% and the analytes could be trapped and separated on the analytical column (C18 Nucleodur). Detection and quantification of sulfonamides in the MS/MS system were done in the Selected Reaction Monitoring (SRM) mode. With the developed online-SPE-LC-MS/MS system it was possible to enrich, measure and quantify simultaneously the following sulfonamides and metabolites during a 30-minute-run with a minimum of sample preparation: Sulfadiazine*, Sulfathiazole*, Sulfamethazine*, Sulfamethoxazole*, Sulfadimethoxine*, Acetylsulfadiazine, Acetylsulfathiazole*, Acetylsulfamethoxazole*, Acetylsulfadimethoxine, Acetylsulfamethazine, (*: marked isotope labelled compounds available). The developed method was successfully applied to the analysis of more than 100 water samples from a field study investigating the input of veterinary sulfonamide antibiotics to suface water.
Key words: online-solid-phase-extraction, sulfonamides, environment, trace-analysis
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