Speciation Analysis\nof Metals and Metalloids by Surface\nEnhanced Raman Spectroscopy

The presence of metalloids and heavy metals in the environment\nis of critical concern due to their toxicological impacts. However,\nnot all metallic species have the same risk level. Specifically, the\nphysical, chemical, and isotopic speciation of the metal(loids) dictate\ntheir metabolism, toxicity, and environmental fate. As such, speciation\nanalysis is critical for environmental monitoring and risk assessment.\nIn the past two decades, surface-enhanced Raman spectroscopy (SERS)\nhas seen significant developments regarding trace metal(loid) sensing\ndue to its ultrahigh sensitivity, readiness for in situ real-time\napplications, and cost-effectiveness. However, the speciation of metal(loid)s\nhas not been accounted for in the design and application of SERS sensors.\nIn this Perspective, we examine the potential of SERS for metal(loid)\nspeciation analysis and highlight the advantages, progress, opportunities,\nand challenges of this application.