What if your morning coffee spill could help detect harmful toxins? Scientists at the Raman Research Institute (RRI) in Bengaluru have found an innovative way to detect toxic substances at ultra-low concentrations. They achieved this by harnessing the “coffee-stain effect,” the phenomenon that makes a dried coffee drop form a dark ring around its edge.

A team of researchers from RRI, Bengaluru focused on Rhodamine B, a fluorescent synthetic dye widely used in textiles and cosmetics. While common in industry, the dye is toxic to humans and can persist in water, posing environmental and health risks .

To detect Rhodamine B, scientists used gold nanorods suspended in water. Droplets of this mixture were placed on a specially prepared silicon surface and left to evaporate naturally.

As th

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