Plate Nº 67 · recorded November 15, 2026
Chemistry & MaterialsReported finding
10-Second Color Test Spots Mercury in Water and Food
Istanbul Technical University chemists built NIR-2, a selenium-based molecule that turns yellow to green within 10 seconds of meeting mercury ions in water, food and even lung cells.
By Marcus Bennett3 min read531 words
In brief
- NIR-2 reacts to mercury ions in about 10 seconds, with a signal stable for at least 20 minutes.
- The sensor turns solutions from yellow to green and emits near-infrared light.
- A smartphone camera reading red and green pixel values estimated mercury levels across a concentration range.
- In human lung cells, cell survival stayed above 90% under tested conditions.
- The study was published in the journal Talanta; it is not yet a consumer home test.
A new molecular sensor detects mercury ions in roughly 10 seconds, changing a test solution from yellow to green and emitting near-infrared light that an ordinary smartphone camera can help measure.
Researchers at Istanbul Technical University designed the molecule, called NIR-2, to attack a stubborn practical problem: mercury contamination is invisible. Contaminated water and food look completely normal, yet the toxic metal can damage the nervous system and other organs even at low concentrations. Conventional testing usually demands specialist equipment and a laboratory, which slows down any response.
The study appeared in the journal Talanta.
How does the sensor work?
NIR-2 exploits a strong chemical attraction. The molecule's structure contains selenium, an element that interacts forcefully with mercury ions — a particular dissolved form of the metal. When selenium meets mercury, the molecule changes shape.
That shape shift produces two readable signals at once: a visible color change from yellow to green, and light in the near-infrared range, which sits beyond what human eyes can see but standard instruments can measure. The researchers call this combination the study's main achievement — a fast color response and a sensitive light signal fused into one molecular design.
The reaction completed in about 10 seconds, and the signal stayed stable for at least 20 minutes, a window long enough for practical readings. In short: one molecule delivers both a quick eyeball check and a quantitative signal.
Can a phone replace the lab?
Partly, and that is the interesting part for practitioners. The team investigated whether a standard smartphone camera could measure the color shift instead of relying entirely on laboratory instruments.
By comparing red and green values in photographs, they estimated mercury levels across a range of concentrations. The approach could eventually move some screening work out of the lab and closer to where contamination occurs, cutting cost and delay.
What did the researchers actually test?
To push beyond simple solutions, the scientists added known amounts of mercury to:
- drinking water
- lake water
- several fruits
- rice, corn, beans and lentils (color responses varied between foods)
In a separate experiment, the sensor produced mercury-related light signals inside human lung cells. Cell survival stayed above 90% under the tested conditions, suggesting NIR-2 may also serve as a research imaging tool for biological samples.
What are the limits?
This is not yet a home test strip. The researchers spell out the constraints plainly:
- Samples required preparation before testing.
- Lighting had to be controlled for the smartphone method to work.
- Most tests used materials deliberately spiked with known mercury amounts, not naturally contaminated ones.
For environmental monitoring, an early warning does not replace a full safety assessment. Authorities still need validated measurements, agreed safety limits, and clear procedures for responding when contamination turns up. A useful field test must also work consistently across different foods and water sources — not only in carefully prepared experiments.
Researchers still need to establish how reliably the sensor performs with naturally contaminated samples and under changing field conditions.
Even so, the work offers a promising route to making an invisible environmental danger visible — and, one day, affordable enough to check with the camera already in your pocket.
via knowridge.com (Source)
More from Marcus Bennett
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News editor covering regulation, policy and their impact on general science news at SciBeat.
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