13-Jun-2022 - American Chemical Society (ACS)

‘E-nose’ sniffs out mixtures of volatile organic compounds

Accurately distinguish xylene isomer mixtures

As paint thinner, ink and adhesives dry, they can release volatile organic compounds (VOCs), which can negatively impact health. Typically, one of those VOCs is xylene, which exists as three isomers with the same elements but slightly different arrangements. Because the isomers are so similar, they’re hard to monitor separately. Now, researchers reporting in ACS Sensors have developed an electric nose (“e-nose”) with porous metal-organic framework (MOF) films that can accurately distinguish xylene isomer mixtures.

Xylene, sometimes called xylol, is harmful if large amounts are inhaled or absorbed through skin. Each isomer, o-xylene, m-xylene and p-xylene, interacts differently in humans and other mammals, so it’s important to monitor the environment for each isomer and not just their cumulative presence. Previously, researchers used gas chromatography analysis to identify the three forms of xylene. But this procedure requires large instruments that are expensive, and the analyses are time intensive. So, Lars Heinke and colleagues wanted to see if MOF films could be incorporated into simple, faster sensors to detect and measure the presence of each isomer separately in the air. 

The researchers prepared six different porous MOF films known to adsorb xylene isomers and applied them to gravimetric sensors in an array called an “e-nose.” In initial experiments, the team showed that the MOF films had different sensitivities to o-xylene, m-xylene and p-xylene. Then, they tested the e-nose’s ability to distinguish xylene isomers within mixtures at concentrations of 10 ppm and 100 ppm, which is the U.S. National Institute for Occupational Safety and Health’s exposure limit. By analyzing the sensor array data with a machine learning algorithm, the team could determine the composition of the mixtures with 86% accuracy for the 10-ppm mixture and 96% accuracy for the 100-ppm mixture. The researchers say that the MOF-based e-nose is a simple device for discriminating the three forms of xylene in environmental monitoring and diagnostic health testing.

American Chemical Society (ACS)

Recommend news PDF version / Print

Share on

Facts, background information, dossiers
  • volatile organic compounds
  • xylene
  • isomers
  • metal organic frameworks
  • electronic noses
  • artificial nose
More about American Chemical Society
  • News

    Mucus could explain why SARS-CoV-2 doesn’t spread easily from surfaces

    Early in the pandemic, many people fastidiously disinfected surfaces because laboratory studies predicted that SARS-CoV-2 could be easily transmitted in this way. Now, researchers reporting in ACS Central Science have found a possible explanation for why the predictions didn’t pan out: Suga ... more

    ‘E-nose’ could someday diagnose Parkinson’s disease by ‘smelling’ skin

    A couple of years ago, a woman named Joy Milne made headlines when scientists discovered that she could “smell” Parkinson’s disease (PD) on people with the neurodegenerative disorder. Since then, researchers have been trying to build devices that could diagnose PD through odor compounds on ... more

    Camels’ noses inspire a new humidity sensor

    Camels have a renowned ability to survive on little water. They are also adept at finding something to drink in the vast desert, using noses that are exquisite moisture detectors. In a new study in ACS Nano, researchers describe a humidity sensor inspired by the structure and properties of ... more

  • Videos

    The chemicals we leave behind

    The products we use every day leave behind chemical footprints. Learn how and why researchers are now studying those trails. Mass spectrometry is helping researchers learn more about our interactions with the everyday chemicals we use, such as DEET, caffeine, even medications. In this episo ... more

More about KIT
  • News

    Neutrinos are lighter than 0.8 electron volts

    The international KArlsruhe TRItium Neutrino Experiment (KATRIN), located at Karlsruhe Institute of Technology (KIT), has broken an important "barrier" in neutrino physics which is relevant for both particle physics and cosmology. Based on data published in the prestigious journal Nature Ph ... more

    Taking Microbes Out of Dark and Into the Light

    Microorganisms are the oldest, most abundant, and most diverse life forms on earth and offer enormous potential for biotechnological applications. To date, however, only a fraction of them could be isolated and cultivated. The “MicroMATRIX” research project, funded with EUR 1.5 million by t ... more

    New Sensor Detects Ever Smaller Nanoparticles

    Nanoparticles are omnipresent in our environment: Viruses in ambient air, proteins in the body, as building blocks of new materials for electronics, or in surface coatings. Visualizing these smallest particles is a problem: They are so small that they can hardly be seen under an optical mic ... more