title: Determination of six sulfonamide antibiotics, two metabolites and trimethoprim in wastewater by isotope dilution liquid chromatography/tandem mass spectrometry.
abstract: A highly sensitive method for the analysis of six sulfonamide antibiotics (sulfadiazine, sulfathiazole, sulfapyridine, sulfamerazine, sulfamethazine and sulfamethoxazole), two sulfonamide metabolites (N(4)-acetyl sulfamethazine and N(4)-acetyl sulfamethoxazole) and the commonly co-applied antibiotic trimethoprim was developed for the analysis of complex wastewater samples. The method involves solid phase extraction of filtered wastewater samples followed by liquid chromatography-tandem mass spectral detection. Method detection limits were shown to be matrix-dependent but ranged between 0.2 and 0.4 ng/mL for ultrapure water, 0.4 and 0.7 ng/mL for tap water, 1.4 and 5.9 ng/mL for a laboratory-scale membrane bioreactor (MBR) mixed liquor, 0.7 and 1.7 ng/mL for biologically treated effluent and 0.5 and 1.5 ng/g dry weight for MBR activated sludge. An investigation of analytical matrix effects was undertaken, demonstrating the significant and largely unpredictable nature of signal suppression observed for variably complex matrices compared to an ultrapure water matrix. The results demonstrate the importance of accounting for such matrix effects for accurate quantitation, as done in the presented method by isotope dilution. Comprehensive validation of calibration linearity, reproducibility, extraction recovery, limits of detection and quantification are also presented. Finally, wastewater samples from a variety of treatment stages in a full-scale wastewater treatment plant were analysed to illustrate the effectiveness of the method.
authors.affiliation: UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, NSW 2052, Australia. minh@student.unsw.edu.au
authors.forename: Nhat
authors.initials: N
authors.lastname: Le-Minh
authors.forename: Richard M
authors.initials: RM
authors.lastname: Stuetz
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Khan
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis*; D002853:Chromatography, Liquid; D060766:Drinking Water / Q000737:chemistry*; D006801:Humans; D007201:Indicator Dilution Techniques; D007553:Isotope Labeling; D057230:Limit of Detection; D012015:Reference Standards; D015203:Reproducibility of Results; D012722:Sewage / Q000737:chemistry*; D052616:Solid Phase Extraction; D013449:Sulfonamides / Q000032:analysis*; D053719:Tandem Mass Spectrometry; D014295:Trimethoprim / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D000900:Anti-Bacterial Agents; D060766:Drinking Water; D012722:Sewage; D013449:Sulfonamides; D014874:Water Pollutants, Chemical; D014295:Trimethoprim