An ion-imprinted material embedded carbon quantum dots for selective fluorometric determination of lithium ion in water samples

An ion-imprinted fluorescent polymer (referred to as CQD@SiO₂@IIP) is presented for recognition of lithium ion. The material is based on the use of carbon quantum dots (CQDs) and is prepared by a surface imprinting technique using benzo-15-crown-5 (B15C5) as the complexing agent, methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the crosslinker, 2,2-azobisisobutyronitrile (AIBN) as the radical initiator, and lithium ion as the template. After optimization of the detection conditions, the relative fluorescence intensity (F₀/F), best measured at excitation/emission wavelength of 360 nm/460 nm, varies linearly with the Li⁺ concentration in the range between 0.5 and 50 μmol·L⁻¹, with a limit of detection of 16 μmol·L⁻¹. Performance was compared to the non-imprinted material, and the imprinting factor is found to be 4.5. The ion-imprinted fluorescence material was applied to the determination of Li⁺ in (spiked) water samples and obtained good recoveries ranged from 102 to 111.6%. [Figure not available: see fulltext.].