A highly sensitive and specific competitive ELISA on 96-microwell plates was developed for the analysis of the nonsteroidal anti-inflammatory drug diclofenac. Within the water cycle in Europe, this is one of the most frequently detected pharmaceutical active compounds. The LOD at a signal-to-noise ratio (S/N) of 3, and the IC50 , were found to be 6 ng/L and 60 ng/L respectively in tap water. In a comparative study using ELISA and GC-MS, diclofenac levels in wastewater from 21 sewage treatment plants were determined and a good correlation between these methods was found (ELISA vs. GC-MS: r = 0.70, slope = 0.90, intercept = 0.37, n = 24). An average degradation rate of ≈25% can be calculated. Labscale-experiments on the elimination of diclofenac in continuous pilot sewage plants revealed a removal rate of only 5% over a period of 13 weeks. In a further study, the ELISA was applied to a number of extracts of various animal tissues from a range of species, and again a very good relationship between ELISA and LC-ESI/MS data sets was obtained (r = 0.90, p<0.0001; n = 117). The ELISA has proven to be a simple, rapid, reliable and affordable alternative to otherwise costly and advanced techniques for the detection of diclofenac in matrix diverse water samples and tissue extracts after only relatively simple sample preparation.
Knopp, D., Deng, A., Letzel, M., Taggart, M.
, Himmelsbach, M., Zhu, Q-Z., ... Niessner, R. (2009). Immunological Determination of the Pharmaceutical Diclofenac in Environmental and Biological Samples
. Rational Environmental Management of Agrochemicals: Risk Assessment, Monitoring, and Remedial Action
, 203-226. https://doi.org/10.1021/bk-2007-0966.ch013