Adsorption and detection of praseodymium ion by ion-imprinted polymer with ultra-low sensitivity.

A novel kind of carbon dot (CD) was prepared by one-step hydrothermal microwave assisted method using L-tryptophan and L-tartaric acid as raw materials. Monodisperse poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) microspheres were utilized as the matrix, with praseodymium (Pr) ion (Pr) as the template, methacrylic acid as the functional monomer, and 5-amino-8-hydroxyquinoline (5-AHQ) acts as the ligand. A composite microsphere of ion-imprinted polymer (IIP) and CD (noted CD@IIP) was prepared by surface-initiated atom transfer radical polymerization (SI-ATRP). For comparison, IIP without CD (Pr-IIP) and non-imprinted polymer (NIP) were also prepared. Through static adsorption experiments, it was  determined that the saturated adsorption amount of CD@IIP is 47.19 mg g, that of Pr-IIP is 54.49 mg g, while that of NIP is only 24.32 mg g. Dynamic adsorption experiments showed that the equilibrium of three kinds of materials was reached within 30 min. Particularly, CD@IIP could emit two fluorescence peaks at 325 nm and 421 nm under ultraviolet irradiation, and exhibited excellent selectivity and fluorescence quenching effect on Pr. The fluorescence response of Pr in the range 0-400 μmol L was determined by ratiometric fluorescence method, offering a two-stage model and robust linear regression coefficient. These results demonstrated that CD@IIP exhibited selective adsorption ability for Pr, and a sensitive, rapid and simple method for detection of Pr was successfully developed.