Development of biomimetic hexapeptide functionalized monolithic material for capillary microextraction of microcystins in environmental waters

In this work, a histidine-tagged hexapeptide functionalized monolithic material is described for the efficient capillary microextraction (CME) of microcystins (MCs) from environment waters. 1-Vinylimidazole (VIM) monomer was utilized to synthesize the matrix polymer monolith by the copolymerization with divinylbenzene (DVB) crosslinker in the presence of radical initiator azobisisobutyronitrile (AIBN). The affinity sorbent was then prepared by a metal ion chelation-based multi-step approach, in which the histidine tag peptide Trp-His-Trp-Leu-Gln-Trp (WHWLQW) was functionalized on a Cu2+ modified polymer monolith via a chelation reaction between the imidazole group of histidine and Cu2+. The resultant WHWLQW functionalized monolithic material had high affinity, hierarchical porosity and good mechanical stability. Especially, it exhibited favorable enrichment capacity for MCs compared to other affinity materials as previously reported. With the optimized CME protocol, MCs at ultra-trace level can be analyzed by CME coupled to high performance liquid chromatography-mass spectrometry (HPLC-MS) in different aqueous environmental matrices. The average recoveries were ranged from 89.3% to 104.5% with relative standard deviations (RSD%) of 2.1–8.4, demonstrating high extraction efficiency and repeatability. The limits of detection (LODs) of MCs were determined to be 0.28–0.45 ng L-1. This novel biomimetic sorbent shows promising potential for the enrichment of ultra-trace pollutants in environment waters.