Rapid Colorimetric Detection of Heavy Metal Hg²⁺ in Cosmetics Based on Amrinone‐Modified AuNPs Sensor

Abstract Mercury is unacceptable as a whitening agent in cosmetics because it is highly toxic and much harmful to the digestive, respiratory, circulatory, and nervous systems of humans. Therefore, it is of fundamental and practical importance to detect whether the concentration of mercury in cosmetics meets national standards. In this work, a new way for the simple visual and rapid colorimetric detection of Hg²⁺ using gold nanoparticle (AuNPs) modified with amrinone (3‐amino‐5‐pyridin −4‐yl‐1H‐pyridin‐2‐one, ALN) is proposed and characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), UV‐vis, Fourier transform infrared (FTIR) and analyzed of Gaussian16w and Multiwfn simulations. The solution colors changed from wine‐red to gray‐blue with increasing Hg²⁺ concentration resulting from the agglomeration of AuNPs with favorable anti‐interference and selectivity. The limit of detection (LOD) is 0.8 μmol/L by the unaided eye, and 18.2 nmol/L by UV‐vis spectroscopy with the excellent linear relationship (R²=0.9935) in the range of 0.0∼6.0 μmol/L (Hg²⁺ concentration), showing that AuNPs modified with ALN can serve as the quantitative determination of Hg²⁺. After testing actual samples, it is found that the test method can be practically applied to the monitoring of heavy metal mercury in cosmetics.