New Cost-Effective Method to Detect Arsenic in Drinking Water

Scientists have unveiled a new optical fiber sensor that enables real-time detection of arsenic in drinking water at levels far below WHO’s safety threshold. This innovation could empower households worldwide to easily monitor water safety and reduce risks associated with arsenic exposure.

A team of researchers from the Indian Institute of Technology Guwahati has developed a new optical fiber sensor that provides a simple, real-time method for detecting arsenic in drinking water at extremely low levels. This innovative technology promises to enable household testing for arsenic, giving individuals the power to monitor their own water quality more effectively.

Arsenic contamination presents a significant environmental and public health crisis, affecting millions around the globe. It naturally leaches into groundwater from rocks and soil but is also exacerbated by human activities, such as mining, industrial waste disposal and the use of arsenic-based pesticides.

“Consuming arsenic-contaminated water can lead to severe health conditions, including arsenic poisoning and cancers of the skin, lung, kidney and bladder,” lead author Sunil Khijwania, a professor in the Department of Physics at IIT Guwahati, said in a news release. “By creating a sensor that is sensitive, selective, reusable and cost-effective, we aim to address the need for a reliable and user-friendly tool for routine monitoring, helping to protect communities from the risks of arsenic exposure.”

Published in the journal Applied Optics, the study details a sensor that uses an optical fiber and a phenomenon known as localized surface plasmon resonance. Remarkably, it can detect arsenic levels as low as 0.09 parts per billion (ppb), which is 111 times lower than the World Health Organization’s maximum permissible limit of 10 ppb.

A User-Friendly Tool for Safer Water

Conventional spectroscopy methods for detecting arsenic, though highly accurate, require complex and expensive equipment that is cumbersome to use.

This new sensor fills a crucial gap by being cost-effective and straightforward enough for routine use, permits real-time monitoring and delivers results within 0.5 seconds.

To develop this sensor, the researchers coated the inside core of an optical fiber with gold nanoparticles and a unique nanocomposite of aluminum oxide and graphene oxide, which selectively binds to arsenic ions.

As light travels through the optical fiber, it interacts with the gold nanoparticles, triggering localized surface plasmon resonance. If arsenic is present, it binds to the sensor’s nanocomposite, causing a detectable shift in wavelength.

Comprehensive testing of the sensor revealed it consistently and reliably detected arsenic across various concentrations, with a maximum resolution of ± 0.058 ppb. It demonstrated negligible variations over multiple days of testing and showed strong agreement with measurements from inductively coupled plasma mass spectrometry (ICP-MS), a gold-standard method for arsenic detection.

Testing on real drinking water samples from diverse locations in Guwahati, India, confirmed the sensor’s reliable performance in real-world conditions.

“These investigations established that the proposed optical fiber sensor offers a highly sensitive, selective, fast, cost-effective, straightforward and easy solution for arsenic detection in real field conditions,” Khijwania added. “In the long term, this new approach could potentially be modified to create a new wave of affordable and accessible environmental monitoring tools.”

Future Prospects

While the sensor is ready for real-world applications, further development of a less expensive and easier-to-use optical source and detector would be necessary for widespread adoption.

The researchers hope that their work will lead to a new standard in water quality testing, potentially saving lives by preventing arsenic exposure and ensuring safer drinking water for communities worldwide.