Rapid and reliable determination of p-nitroaniline in wastewater by molecularly imprinted fluorescent polymeric ionic liquid microspheres

- A novel MIPIL microspheres for fluorescent sensing of p-nitroaniline was described.
- Strong emission of anthracene fluorophore coupled ionic liquid monomer was obtained.
- The response time needed in p-nitroaniline sensing was only 1 min.
- The MIPIL microspheres sensor could recognize p-nitroaniline from its analogs.
- The p-nitroaniline fluorescent detection results in real water samples are in well accordance with HPLC measurements.

Rapid and efficient detecting trace amount of environmental p-nitroaniline (p-NA) is in urgent need for security concerns and pollution supervision. In this work we report the use of molecularly imprinted polymeric ionic liquid (MIPIL) microspheres to construct recognizable surfaces for detection of p-NA through fluorescence quenching. The p-NA imprinted microspheres are synthesized by precipitation polymerization upon co-polymerization of 3-(anthracen-9-ylmethyl)-1-vinyl-1H-imidazol-3-ium chloride (Fluorescent IL monomer) with ethyleneglycol dimethacrylate (EGDMA). The electron-rich group alkenyl imidazole in IL functional monomer can dramatically improve the emission of anthracene fluorophore and the π-π stacking, electronic, and hydrogen bond between p-NA and MIPIL can efficiently enhance the selective recognition force. The as-synthesized MIPIL microspheres present spherical shape, high fluorescence emission intensity and specific recognition, which showed rapid detection rate (1 min), stable reusable property (at least 4 time recycles), wonderful selectivity over several structural analogs, wide linear range (10 nM to 10 M) with a correlation coefficient of 0.992, and excellent sensitivity (LOD, 9 nM). As synthesis and surface functionalization of MIPIL microspheres are well established, the methods reported in this work are facile, rapid and efficient for monitoring p-NA in environmental wastewater.