Reddersen K, Heberer Th
Institute of Food Chemistry, Technical University Berlin, Gustav-Meyer-Allee 25, Sekr. TIB 413-1, 13355 Berlin, Germany.
J Chromatogr A. 2003 Sep 5;1011(1-2):221-6. doi: 10.1016/s0021-9673(03)01173-7.
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.
