title: Residue analysis of the pharmaceutical diclofenac in different water types using ELISA and GC-MS.
abstract: A highly sensitive and specific indirect competitive enzyme-linked immunosorbent assay (ELISA) for the determination of diclofenac in water samples was developed. With pure water, the limit of detection (LOD, S/N = 3) and IC50 were found to be 6 ng/L and 60 ng/L, respectively. The analytical working range was about 20-400 ng/L. Highest cross-reactivity (CR) of 26 tested pharmaceuticals, metabolites, and pesticides was found for 5-hydroxydiclofenac (100%). Other estimated values were well below 4% and, therefore, are negligible. The assay was applied for the determination of diclofenac in tap and surface water samples as well as wastewater collected at 20 sewage treatment plants (STPs) in Austria and Germany. Humic substances were identified as main interference in surface water. Wastewater samples which were only submitted to filtration and dilution yielded about 25% higher diclofenac concentrations using the ELISA compared to GC-MS. However, the ELISA turned out to be a simple, inexpensive, and accurate method for the determination of diclofenac both in influent and effluent wastewater after rather simple sample preparation, i.e., filtration, acidification, and readjustment to neutral pH-value, and at least 10-fold dilution with pure water.
authors.affiliation: Institute of Chemistry, Department of Analytical Chemistry, Johannes-Kepler-University Linz, Altenbergerstrasse 69, A-4040 Linz, Austria.
authors.forename: Anping
authors.initials: A
authors.lastname: Deng
authors.forename: Markus
authors.initials: M
authors.lastname: Himmelsbach
authors.forename: Qing-Zhi
authors.initials: QZ
authors.lastname: Zhu
authors.forename: Siegfried
authors.initials: S
authors.lastname: Frey
authors.forename: Manfred
authors.initials: M
authors.lastname: Sengl
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Buchberger
authors.forename: Reinhard
authors.initials: R
authors.lastname: Niessner
authors.forename: Dietmar
authors.initials: D
authors.lastname: Knopp
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000032:analysis*; D004008:Diclofenac / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D004797:Enzyme-Linked Immunosorbent Assay; D008401:Gas Chromatography-Mass Spectrometry; D012680:Sensitivity and Specificity; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D014874:Water Pollutants, Chemical; D004008:Diclofenac