Preparation of a new polymeric ionic liquid-based monolith for stir cake sorptive extraction and its application in the extraction of inorganic anions

In this study, a novel stir cake sorptive extraction (SCSE) sorbent based on polymeric ionic liquid-based monolith (PILM) for the extraction of inorganic anions was prepared. In the presence of a porogen solvent containing 1-propanol and dimethylformamid, an ionic liquid, 1-ally-3-methylimidazolium chloride was used as monomer to copolymerize in situ with ethylene dimethacrylate to form PILM. The effect of preparation conditions such as ratio of functional monomer to cross-linker, content of porogenic solvent on the extraction efficiencies were investigated in detail. The PILM was characterized by elemental analysis, scanning electron microscopy, mercury intrusion porosimetry and infrared spectroscopy. In order to investigate the extraction capacity of PILM-SCSE for inorganic anions, the SCSE was combined with ion chromatography with conductivity detection, F−, Cl−, NO2−, Br−, NO3−, PO43− and SO42− were selected as detected solutes. Several extractive parameters, including pH values in sample matrix, desorption solvent, extraction and desorption time were optimized. The results showed that under the optimum experimental conditions, low detection limits (S/N = 3) and quantification limits (S/N = 10) of the proposed method for the target anions were achieved within the range of 0.11–2.08 and 0.37–6.88 μg/L, respectively. The method also showed good linearity, simplicity, practicality and low cost for the extraction inorganic anions. Finally, the proposed method was successfully used to detect different water samples include commercial purified water, tab water and river water. Acceptable recoveries and satisfactory repeatability were obtained. To the best of our knowledge, this is the first to use polymeric ionic liquid to enrich inorganic anions.

► A new polymeric ionic liquid-based monolith (PILM) was first prepared.
► PILM was used as the sorbent of stir cake sorptive extraction (SCSE).
► The PILM-SCSE possessed high anion-exchange capacity.
► Combination of PILM-SCSE-LD-IC/CD was successfully used to analyze inorganic anions.