A new polymeric ionic liquid-based magnetic adsorbent for the extraction of inorganic anions in water samples

• A new polymeric ionic liquid-based magnetic adsorbent was prepared.
• The PIL/MNPs-MSPE could extract anions effectively with ion-exchange interaction.
• The extraction parameters were investigated in detail.
• Method of sensitive monitoring of inorganic anions in water samples was developed.

In this work, a novel type of polymeric ionic liquid (PIL)-based magnetic adsorbent was successfully synthesized and applied for the extraction and determination of seven inorganic anions in water samples by coupling with ion chromatography. The new adsorbent was synthesized by simple free radical copolymerization of 1-ally-3-vinylimidazolium chloride, ethylene glycol dimethacrylate and silica-coated magnetite. The adsorbent exhibited well-defined core-shell structure and good magnetic response ability. Furthermore, due to the presence of abundant anion-exchange groups in the PIL, the adsorbent displayed expected extraction performance for anions including F−, Cl−, Br−, NO2−, NO3−, PO43− and SO42−. Various experimental parameters that could affect the extraction performance, such as the amount of adsorbent, desorption solvent, extraction and desorption time, the pH value of sample solution were investigated in detail. Under the optimized conditions, low limits of detection (S/N = 3) and quantification limits (S/N = 10) of the proposed method for the target anions were achieved within the range of 0.061–0.73 μg/L and 0.19–2.41 μg/L, respectively. The repeatability was investigated by evaluating the intra-day, inter-day precisions and batch-to-batch reproducibility with relative standard deviations (RSDs) lower than 11%. At the same time, the method also showed high extraction speed, simplicity, practicality and low cost for the extraction inorganic anions. Finally, the proposed method was used to detect anions in different water samples successfully. The recoveries were in the range of 71.0–111%, and the RSDs were below 12% in the all cases.