A highly selective solid-state fluorescent sensor based on N-doped carbon quantum dots (N-CQDs) and cotton fiber paper (CFP) is reported for the determination of trace mercury (II)(Hg2+). The N-doped carbon quantum dots on cotton fiber paper (N-CQDs@CFP) was synthesized using a facile one-step microwave hydrothermal method. Multiple approaches were employed to fully investigate the morphology and chemical structure of the paper-based fluorescent sensor. The N-CQDs were chemically bonded onto the CFP, which offers good reproducibility and stability of the sensor. The N-CQDs@CFP showed high-intensity blue emission in dark-field imaging, and the fluorescence was quenched by Hg2+. The Hg2+ in aqueous samples was easily determined and visually monitored. There was good linearity from 0 to 250 μM, and the limit of detection was 34 nM. The paper-based fluorescent sensor provided accurate and rapid determination of Hg2+ upon comparison with flame atomic absorption spectrophotometry (FAAS). The simple preparation, rapid detection (< 5 min), low cost, and easy-handling illustrate that the reported sensor has a significant value in environmental monitoring.
As an ideal alternative to bisphenol A (BPA), bisphenol S (BPS) has similar biotoxicity, teratogenicity , carcinogenicity and mutagenicity as BPA. Nevertheless, to date, a fast, sensitive and portable method for meeting on-site measurement of BPS had not been established. Hence, it was particularly urged to develop a fast and highly sensitive method for tracing BPS. Currently, a novel molecularly imprinted polymer (MIP) electrochemical sensor had been successfully fabricated for the detection of BPS, wherein the composite of three-doped carbon quantum dots (B, N, F-CQDs) and silver nanoparticles (AgNPs) were utilized as an electron conducting layer, and MIP was applied as recognition element of target molecules. The step-by-step fabrication process and the adsorption capacity of the modified electrode were evaluated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronocoulometry (CC). The results indicated that the synergy between B, N, F-CQDs and AgNPs dramatically improved the sensitivity of the electrode and achieved the amplification of the electrical signal. Meanwhile, the electrochemical activities of BPS were explored by CV and differential pulse voltammetry (DPV). And, the various parameters relating to the electrochemical kinetic properties of BPS were calculated. To the best of our knowledge, this was rarely reported in peer journals. The MIP remarkably improved the selectivity of the sensor owing to the specific recognition of the imprinted cavities. The linear response range of the new sensor was 1 × 10 −8 M to 5 × 10 −5 M with a detection limit of 1.12 × 10 −8 M and the electrode designed in this paper could meet the requirement of trace-level measurement of BPS in biological and environmental samples. Additionally, the sensor was used to determine BPS in plastic products with good anti-interference and acceptable recovery.
危险品化学品经营许可证（带存储）