As part of an international team, scientists from Paderborn University have developed a new method to quickly and accurately detect toxic arsenic variants in soil and water. The study, which was published in the journal "Nanoscale" of the Royal Society of Chemistry, shows how simple technologies can replace expensive laboratory procedures and enable rapid on-site analysis.
Not all arsenic is the same
Arsenic is a dangerous heavy metal that can be found in soil and water. However, it is not only the quantity of arsenic that is decisive: the toxicity depends heavily on the chemical form in which the arsenic is present. Researchers must therefore be able to distinguish precisely whether it is arsenic(III) or arsenic(V). "These two forms behave completely differently in the environment and also have different effects on health. Until now, however, measurements at this high level have been very expensive and complicated," explains Professor Dr Thomas Zentgraf from the Department of Physics at Paderborn University.
Currently, the so-called SERS method (SERS = "Surface-Enhanced Raman Scattering") is generally used to detect traces of arsenic. This is a highly sensitive analytical technique that combines conventional Raman spectroscopy with nanostructured metal surfaces. This amplifies the Raman signal of the molecules a million-fold, so that even the smallest traces of chemical or biological substances can be clearly identified. However, the method is preceded by complex manufacturing processes that often require special machines and expensive materials. In addition, sensors often have to be treated with chemicals in order to work reliably. "Analysing the data also often requires powerful computers and expensive measuring devices that cannot simply be used on site," adds Professor Zentgraf.
Fast, inexpensive and can be used on site
The researchers have developed a new solution. They use a special structure, the "hole-sphere nanogap platform". They use gold nanoparticles that arrange themselves independently on a gold surface. They then treat the surface with heat and lightly etch it. This step replaces complicated lithography, i.e. structuring by means of exposure to light. The result is a platform that works extremely reliably. The researchers have shown that the measurement results hardly fluctuate. The method amplifies the light signal by a factor of 100 million. This means that even the smallest amounts of arsenic are clearly visible. As the structure is made entirely of metal, no other signals from the material interfere with the measurement. This makes the results very reliable.
The biggest advantage of the new method is its simplicity. It does not require any expensive machines or special chemicals. The platform works reliably even if the measuring devices are not of the highest precision. For example, the researchers have shown that they can even recognise the arsenic variants using simple filters or smartphones. This makes the method ideal for use in the field, e.g. on construction sites or in agriculture.
To the paper: https://pubs.rsc.org/en/content/articlelanding/2026/nr/d5nr03414k
This text was translated automatically.
