Screening of synthesis conditions for the development of a radium ion-imprinted polymer using the dummy template imprinting approach

Abstract

In this study, a selective and specific sorbent for radium extraction was developed for the first time using ion-imprinted polymer technology. A novel and original approach was used in order to screen the best synthesis conditions. After identifying the best monomer candidates, porogen, and complexation time from electrospray ionization mass spectrometry experiments, solubility tests, and conductimetry experiments, five ion-imprinted polymers (IIPs) were synthesized by bulk polymerization using Ba2+ as a dummy template ion. Non-imprinted polymers (NIPs) were similarly prepared but without template ions. Polymers were packed in solid phase extraction (SPE) cartridges for their characterization. Composition of the percolation and washing solutions (e.g. buffer concentration, nature and pH, and ethanol proportion) was varied to achieve the highest retention for the template ion while minimizing that of interfering ions. The retention, selectivity (retention on IIP versus on NIP), and specificity (targeted ions versus interfering ions) properties of the different polymers were compared by measuring the recovery yields in the SPE collected fractions by inductively coupled plasma mass spectrometry (ICP-MS). The IIP synthesized in acetonitrile/dimethylsulfoxyde (1/1, v/v) using Ba2+ as template ion, vinylphosphonic acid as complexing monomer, and styrene and divinylbenzene as co-monomer and cross-linker showed both selectivity and specificity. It retained strongly Ra2+ while having the potential to isolate it from alkali metals, metalloids and some transition metals.