Comprehensive evaluation of imidazole-based polymers for the enrichment of selected non-steroidal anti-inflammatory drugs.

This study reports the comparison of four manufactured imidazole-based copolymers and two commercially available hydrophilic sorbents for the solid phase extraction (SPE) of selected non-steroidal anti-inflammatory drugs (NSAID). Different hydrophilic copolymers were obtained by a suspension polymerization using a styrene-based and a methacrylate-based cross-linker and by single step modifications for enhancing the ion-exchange character. SPE protocols were optimized for both non-modified and modified sorbents and applied for the enrichment of selected NSAID using all six copolymers. Comparison and evaluation were carried out by determining recovery rates of standard mixtures at different concentration levels ranging from 0.5mgL(-1) to 10mgL(-1) and by the enrichment of spiked human urine at two concentration levels. In order to gain insight into the complexity of the biological sample and its reduction after solid phase extraction, UHPLC-MS analysis and following database comparison was performed for the three mixed-mode strong anion-exchange sorbents. In order to prove the applicability of the modified imidazole-based polymers for the enrichment of NSAID in surface water, river water or groundwater, solid phase extraction was performed with 10ppb of NSAID which resulted into enhanced enrichment by a hundredfold.