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Chemical Imaging Gives Insight Into Early Earth

chemical imaging, desorption electrospray ionization, mineral surface analysis
Experimental set-up used for chemical imaging of rock surfaces by a technique known as desorption electrospray ionization (Image credit: Rachel V. Bennett, Georgia Institute of Technology)

This Research in Action article was provided to LiveScience in partnership with the National Science Foundation.

Rock surfaces often have a variety of colors and textures. Each of these variations actually indicates a different mineral composition. A great number of different chemical reactions can occur on rock surfaces, making them hotbeds of exciting chemistry.

Researchers from the Center for Chemical Evolution, a NASA/National Science Foundation Center for Chemical Innovation, are studying the formation of complex biomolecules that carry genetic information, such as DNA, RNA and proteins, from simple compounds that may have been present on Earth before life existed on the planet (the Earth's pre-biotic period). Studies of prebiotic chemistry investigate complex systems, including the roles of gases, rocks and pools of liquid. One question these studies ask is, "What were the ideal conditions for formation of complex biomolecules?" Researchers are tackling this question from all angles, including analyzing the kinds of rock surfaces that could have been involved in key chemical reactions on early Earth.

Scientists use a technique known as desorption electrospray ionization (DESI) to generate chemical fingerprints of various surfaces, including rock surfaces. DESI equipment works like a miniature power-washer that sprays the surface of a rock sample. The chemicals that are washed off the surface by the power-washer travel in ionized form through the air into an inlet connected to a mass spectrometer — an instrument that measures the masses and relative concentrations of atoms and molecules and thereby helps identify the compositions of the chemicals. By then using the DESI equipment to scan across the sample surface, it is able to create a map of the molecules that are present.

To learn more about conditions that led to the formation of complex biomolecules like DNA and RNA, scientists create chemical reactions that model those on prebiotic Earth. With the help of DESI, they are analyzing rock samples that more closely resemble the rocks on prebiotic Earth (such as meteorites) and creating an inventory of building blocks that form biological systems.

The impact of DESI reaches far beyond the analysis of mineral surface reactions. Applications include the analysis of tissue samples to identify biomarkers of disease, detection of natural medicinal products from sources such as marine algae and characterization of mixtures separated on surfaces by other traditional chemistry methods.

Editor's Note: Any opinions, findings and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation. See the Research in Action archive.