Robotic arm probes chemistry of 3-D objects by mass spectrometry
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Date posted: 25/03/2014
Posted by: Site Administration
This story is from the category
 Pure Research

When life on Earth was first getting started, simple molecules bonded together into the precursors of modern genetic material. A catalyst would have been needed, but enzymes had not yet evolved. One theory is that the catalytic minerals on a meteorite's surface could have jump-started life's first chemical reactions. But scientists need a way to directly analyze these rough, irregularly shaped surfaces. A new robotic system at Georgia Tech's Center for Chemical Evolution could soon let scientists better simulate and analyze the chemical reactions of early Earth on the surface of real rocks to further test this theory.

In a proof-of-concept study, scientists selected a region for analysis on round or irregularly-shaped objects using a 3-D camera on a robotic arm, which mapped the 3-dimentional coordinates of the sample's surface. The scientists programmed the robotic arm to poke the sample with an acupuncture needle. The needle collected a small amount of material that the robot deposited in a nearby mass spectrometer, which is a powerful tool for determining a substance's chemical composition.

"You see the object on a monitor and then you can point and click and take a sample from a particular spot and the robot will go there," said Facundo Fernandez, a professor in the School of Chemistry and Biochemistry, whose lab led the study. "We're using an acupuncture needle that will touch very carefully on the surface of the object and then the robot will turn around and put the material inside of a high resolution mass spectrometer."

Mass spectrometry is a powerful tool for analyzing surface chemistry or for identifying biological samples. It's widely used in research labs across many disciplines, but samples for analysis typically have to be cleaned, carefully prepared, and in the case of rocks, cut into thin, flat samples. The new robotic system is the first report of a 3-D mass spectrometry native surface imaging experiment.

"Other people have used an acupuncture needle to poke a sample and then put that in mass spec, but nobody has tried to do a systematic, three-dimensional surface experiment," Fernandez said. "We are trying to push the limits."

To show that the system was capable of probing a three-dimensional object, the researchers imprinted ink patterns on the surfaces of polystyrene spheres. The team then used the robotic arm to model the surfaces, probe specific regions, and see if samples collected were sufficient for mass spectrometry analysis. The researchers were able to detect inks of different colors and create a 3-D image of the object with sufficient sensitivity for their proof-of-principle setup, Fernandez said.

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