A rapid magnetic bead-based immunoassay for sensitive determination of diclofenac

Alexander Ecke,Tanja Westphalen,Jane Hornung,Michael Voetz,Rudolf J Schneider

doi:10.1007/s00216-021-03778-7

Abstract

Increasing contamination of environmental waters with pharmaceuticals represents an emerging threat for the drinking water quality and safety. In this regard, fast and reliable analytical methods are required to allow quick countermeasures in case of contamination. Here, we report the development of a magnetic bead-based immunoassay (MBBA) for the fast and cost-effective determination of the analgesic diclofenac (DCF) in water samples, based on diclofenac-coupled magnetic beads and a robust monoclonal anti-DCF antibody. A novel synthetic strategy for preparation of the beads resulted in an assay that enabled for the determination of diclofenac with a significantly lower limit of detection (400 ng/L) than the respective enzyme-linked immunosorbent assay (ELISA). With shorter incubation times and only one manual washing step required, the assay demands for remarkably shorter time to result (< 45 min) and less equipment than ELISA. Evaluation of assay precision and accuracy with a series of spiked water samples yielded results with low to moderate intra- and inter-assay variations and in good agreement with LC–MS/MS reference analysis. The assay principle can be transferred to other, e.g., microfluidic, formats, as well as applied to other analytes and may replace ELISA as the standard immunochemical method.Graphical abstract

Highlights

The nonsteroidal anti-inflammatory drug (NSAID) diclofenac (DCF, Fig. 1) has been used frequently in the treatment of rheumatic diseases, inflammations, and fever, as well as acute and chronic pain since its introduction in the 1970s [1, 2]
Insufficient degradation in wastewater treatment plants (WWTPs) promotes introduction of DCF into surface waters where its ecotoxicological effects can lead to disruption of whole biosystems [6,7,8,9,10,11,12]
DCF has been proposed as a priority substance and was added to the EU watchlist for substances of concern requiring Union-wide monitoring in the field of water policy [13]

Summary

Introduction

The nonsteroidal anti-inflammatory drug (NSAID) diclofenac (DCF, Fig. 1) has been used frequently in the treatment of rheumatic diseases, inflammations, and fever, as well as acute and chronic pain since its introduction in the 1970s [1, 2]. Insufficient degradation in wastewater treatment plants (WWTPs) promotes introduction of DCF into surface waters where its ecotoxicological effects can lead to disruption of whole biosystems [6,7,8,9,10,11,12]. DCF has been proposed as a priority substance and was added to the EU watchlist for substances of concern requiring Union-wide monitoring in the field of water policy [13]. In this context, environmental quality standards for DCF in inland waters of 100 ng/L and 10 ng/L in all other surface waters were proposed [14].

Methods

Results

Conclusion