Nitrogen and zinc doped carbon quantum dots for rapid and accurate detection of mercury ions in cosmetics

Rapid and reliable detection technologies for mercury ion in cosmetics are critical for public health. In this study, we synthesized nitrogen and zinc doped carbon quantum dots (N, Zn-CDs) with bright and stable fluorescence using the hydrothermal method. Structure characterization reveals the abundant oxygen- and nitrogen-containing functional groups on the surface of N, Zn-CDs, which readily coordinate with Hg2+, resulting in fluorescence quenching. Basing on this, a rapid and simple quantitative analysis method for Hg2+ detection was designed. By optimizing the detection conditions, a good linear relationship in the range of 0 to 10 μM and a low detection limit of 0.023 μM were achieved. Besides, interference tests demonstrate the presence of other metal ions does not interfere with Hg2+ detection. When detecting Hg2+ in four types of cosmetics spiked with the ion, the sensor achieved recovery rates of 98.27 %, 110.03 %, 100.90 %, and 108.80 %, respectively, with relative standard deviations all under 6.90 %, demonstrating its capability to identify Hg2+ in complex matrices. This research offers a novel approach for the rapid and accurate detection of mercury in cosmetics.