Carbon dots-modified paper-based chemiluminescence device for rapid determination of mercury (II) in cosmetics

Here, a simple and portable paper-based analytical device (PAD) based on the inherent capability of carbon quantum dots (CQDs) to serve as a great emitter for the bis(2,4,6-trichlorophenyl)oxalate (TCPO)–hydrogen peroxide (H₂O₂) chemiluminescence (CL) reaction is introduced for the detection of harmful mercury ions (Hg²⁺). The energy is transferred from the unstable reaction intermediate (1,2-dioxetanedione) to CQDs, as acceptors, and an intensive orange-red CL emission is generated at ~600 nm, which is equal to the fluorescence emission wavelength of CQDs. The analytical applicability of this system was examined for the determination of Hg²⁺. It was observed that Hg²⁺ could significantly quench the produced emission, which can be attributed to the formation of a stable and nonluminescent Hg²⁺–CQDs complex. Accordingly, a simple and rapid PAD was established for monitoring Hg²⁺, with a limit of detection of 0.04 μg ml⁻¹. No interfering effect on the signal was found from other examined cations, indicating the acceptable specificity of the method. The designed assay was appropriately utilized to detect Hg²⁺ ions in cosmetic samples with high efficiency. It was characterized by its low cost, ease of use, and was facile but accurate and high selective for the detection of Hg²⁺ ions. In addition, the portability of this probe makes it suitable for on-site screening purposes.