| Summary: | A rapid, cost-effective, and sample-preparation-free approach is proposed for the quantitative detection of arsenic in drinking water, using surface-enhanced Raman spectroscopy (SERS). This fabrication entailed comprehensive optimization of chemically synthesized silver colloidal nanoparticles, focusing on parameters such as centrifugation time and speed to attain maximal nanoparticle concentration while mitigating interference from trisodium citrate and other chemical agents. Subsequently, SERS substrates were fabricated by depositing a concentrated drop of colloidal silver nanoparticles onto hydrophobic silicon substrates using the drop-coating technique. The drying process induced a coffee-ring effect, resulting in a pronounced spatial variation of nanoparticle concentration, with significantly higher densities observed in the peripheral ring regions compared to the central regions of the substrate. These regions possess the ability to enhance the Raman spectrum of arsenic, enabling the detection of arsenic at concentrations as low as 50 ppb. This method can prove highly valuable for initial field analyses of drinking water.
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