Hypercrosslinked polymer microspheres with weak anion-exchange character: Preparation of the microspheres and their applications in pH-tuneable, selective extractions of analytes from complex environmental samples

In the present study, we describe the preparation of two high-specific-surface area hypercrosslinked polymer resins (HXLPPs) in the form of monodisperse microspheres with average diameters around 6 μm, modified subsequently with two amine moieties: 1,2-ethylenediamine (EDA) and piperazine. The two resins were evaluated subsequently as weak anion-exchange (WAX) sorbents in solid-phase extraction (SPE), with the aim being to extract a group of acidic compounds from complex environmental samples and thereby free them from basic compounds, including interferences. The new hypercrosslinked sorbents with WAX capacity (HXLPP-WAX) were benchmarked against commercial, macroporous sorbents, namely Oasis-WAX and Strata-X-AW, and to the corresponding neutral sorbents, namely the HXLPP precursor, Oasis-HLB and Strata-X, with promising results. The off-line SPE method developed using the WAX sorbents was applied to Ebre river water samples and led to high recoveries of all the analytes when 500 ml of sample was applied to the cartridges, whereas lower recoveries were obtained with the neutral sorbents. The HXLPP-WAX resin modified with the EDA moiety displayed the most attractive overall performance characteristics; it was tested further with 1000 ml of Ebre river water samples, spiked at lower levels of the analyte mixture, and with effluent waste water from a treatment plant. In both cases, the resin provided good recoveries and net chromatogram, due to the ion-exchange moieties which enable the selective extraction of target compounds.