A quick and cheap way to test water quality
Engineers at the University of Michigan have developed a strip of paper that can quickly detect a toxin in drinking water.
The paper strips perform 28 times faster than the complicated method most commonly used today to detect microcystin-LR, a chemical compound produced by the blue-green algae (cyanobacteria) commonly found on nutrient-rich waters.
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Microcystin-LR (MC-LR) is among the leading causes of biological water pollution. Even in very small quantities, it is suspected to cause liver damage and possibly liver cancer. MC-LR is believed to be a culprit of mass poisonings. Water treatment plants—even in developed countries—can’t always remove MC-LR completely, nor can they test for it often enough. The new biosensor provides a quick, cheap, and sensitive test that could allow water treatment plants and individuals to verify the safety of water on a more regular basis. The technology could easily be adapted to detect a variety of harmful chemicals or toxins in water or food. |
Tests for toxin detection |
The sensor works by measuring the electrical conductivity of the nanotubes in the paper. Before the nanotubes are impregnated in the paper, they are mixed with antibodies for MC-LR. When the paper strips come in contact with water contaminated with MC-LR, those antibodies squeeze in between the nanotubes to bond with the MC-LR. This changes their electrical conductivity, which is then measured by an external monitor.
The whole device is about the size of a home pregnancy test, developers say. Results appear in fewer than 12 minutes. To adapt the biosensor for other toxins, it is enough to simply replace the antibodies.
Source: gizmag.com
