This paper reported a real-time detection strategy for Hg²⁺ inspired by the visible spectrophotometer that used a smartphone as a low-cost micro-spectrometer. In combination with the smartphone’s camera and optical accessories, the phone’s built-in software can process the received light band image and then read out the spectral data in real time. The sensor was also used to detect gold nanoparticles with an LOD of 0.14 μM, which are widely used in colorimetric biosensors. Ultimately, a gold nanoparticles-glutathione (AuNPs-GSH) conjugate was used as a probe to detect Hg²⁺ in water with an LOD of 1.2 nM and was applied successfully to natural mineral water, pure water, tap water, and river water samples.

Excessive emissions of heavy metals not only cause environmental pollution but also pose a direct threat to human health. Therefore, rapid and accurate detection of heavy metals in the environment is of great significance. Herein, we propose a method based on laser-induced breakdown spectroscopy (LIBS) combined with filter paper modified with bovine serum albumin-protected gold nanoclusters (LIBS-FP-AuNCs) for the rapid and sensitive detection of Cr³⁺ and Mn²⁺. The filter paper modified with AuNCs was used to selectively enrich Cr³⁺ and Mn²⁺. Combined with the multi-element detection capability of LIBS, this method achieved the simultaneous rapid detection of Cr³⁺ and Mn²⁺. Both elements showed linear ranges for concentrations of 10–1000 μg L⁻¹, with limits of detection of 7.5 and 9.0 μg L⁻¹ for Cr³⁺ and Mn²⁺, respectively. This method was successfully applied to the determination of Cr³⁺ and Mn²⁺ in real water samples, with satisfactory recoveries ranging from 94.6% to 105.1%. This method has potential application in the analysis of heavy metal pollution.