title: Formation of an artifact of diclofenac during acidic extraction of environmental water samples.
abstract: Solid-phase extraction at an acidic pH is used as a common sample preparation method for analyzing residues of the analgesic drug diclofenac (2-[(2,6-dichlorophenyl)amino] benzeneacetic acid) in environmental water samples. This paper describes the matrix-dependent formation of an artifact of diclofenac during sample preparation resulting in an up to 40% underestimation of diclofenac concentrations especially in matrix-prone samples such as sewage effluents or surface water. The artifact most likely being formed during acidification of the sample was unequivocally identified as 1-(2,6-dichlorophenyl)indolin-2-one by capillary gas chromatography-mass spectrometry. To avoid an underestimation of the analytical results quantification of both diclofenac and its artifact is recommended.
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000032:analysis*; D004008:Diclofenac / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D014874:Water Pollutants, Chemical; D004008:Diclofenac