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Scientists say that they have created an inexpensive system, using a smartphone and a lens made with an ink jet printer, capable of detecting lead in tap water at levels generally accepted as dangerous.
The system, described in the journal Analytical Chemistry, combines nano-colorimetry with dark-field microscopy, integrated with the microscope platform of the smartphone to detect lead levels below the safety threshold set by the Environmental Protection Agency (EPA).
"The nano-colorimetry of smart phones is fast, inexpensive and can allow citizens to test the lead content of drinking water on demand in virtually any environment," said Wei-Chuan Shih, associate professor at University of Houston in the United States.
Even small amounts of lead can cause serious health problems, as young children are particularly vulnerable to neurological damage.
According to EPA standards, lead concentrations in drinking water must be less than 15 parts per billion, and Mr. Shih said the consumer test kits currently available are not enough sensitive to accurately detect lead at this level.
The latest application incorporates color analysis to detect lead particles at the nanoscale.
The researchers built a stand-alone smartphone microscope that can work in both fluorescence and dark field imaging and combined it with an inexpensive smartphone with an 8-megapixel camera.
They added tap water with varying amounts of lead, ranging from 1.37 parts per billion to 175 parts per billion.
They then added chromate ions, which react with lead to form lead chromate nanoparticles; Nanoparticles can be detected by combining colorimetric analysis and microscopy.
The analysis measured both the intensity detected by the nanoparticles, the correlation with the lead concentration and verified that the reaction was stimulated by the presence of lead.
The mixture was transferred to a polydimethylsiloxane plate attached to a glass slide; after drying, deionized water was used to rinse the chromate compound and the remaining sediment was imaged for analysis.
Microscopic imaging capacity has proven essential, said Shih, because the amount of sediment was too small to be imaged with an unattended smartphone camera, making it impossible to detect relatively low levels of lead. .
According to Shih, it is essential to rely on the microscopic platform of the smartphone to create a useful consumer product.
"We wanted to make sure we could do something that would be useful from the point of view of lead detection at the EPA standard," he said.
(This article has not been modified by Business Standard staff and is generated automatically from a syndicated feed).
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