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NASA brews better test to find ET in cosmic cocktails

Take an alien liquid, stir, add lasers, then wait to see what rises to the top

Space agency NASA has created a test 10,000 times more sensitive than current technology to detect signs of life beyond Earth.

Scientists hope to use the enhanced "capillary electrophoresis", an improvement on a three-decade old technique, in explorations of liquid-laden locales such as Europa where the test could help detect more amino acids in single tests and in more salty liquids.

The technique, decribed in the paper Enhanced Resolution of Chiral Amino Acids with Capillary Electrophoresis for Biosignature Detection in Extraterrestrial Samples [PDF] used laser-induced fluorescence detection, a technique that sees a laser shone through mixtures of molecules to observe and sort them.

Boffins at NASA's Jet Propulsion Laboratory tested the technique at Mono Lake in California where the highly alkaline waters make it difficult for life to survive. The 17 biotic and abiotic amino acids that were found were labeled the Signature 17 standard.

Principal investigator Peter Willis says the new test is tuned to detect left handed amino acids - a description for one of the two Chiral forms of amino acids - which are one of the most powerful signatures of Earth-based life.

"Using our method, we are able to tell the difference between amino acids that come from non-living sources like meteorites versus amino acids that come from living organisms," Willis says.

"Our best chance of finding life is by using powerful liquid-based analyses like this one on ocean worlds."

Here's how NASA explains the situation:

Amino acids are fundamental building blocks of terrestrial life as well as ubiquitous byproducts of abiotic reactions. In order to distinguish between amino acids formed by abiotic versus biotic processes it is possible to use chemical distributions to identify patterns unique to life.

This article describes two capillary electrophoresis methods capable of resolving 17 amino acids found in high abundance in both biotic and abiotic samples (seven enantiomer pairs d/l-Ala, -Asp, -Glu, -His, -Leu, -Ser, -Val and the three achiral amino acids Gly, β-Ala, and GABA). To resolve the 13 neutral amino acids one method utilizes a background electrolyte containing γ-cyclodextrin and sodium taurocholate micelles.

The acidic amino acid enantiomers were resolved with γ-cyclodextrin alone. These methods allow detection limits down to 5 nM for the neutral amino acids and 500 nM for acidic amino acids and were used to analyze samples collected from Mono Lake with minimal sample preparation.

Postdoctoral researcher Jessica Creamer says the process is simple.

"Our method improves on previous attempts by increasing the number of amino acids that can be detected in a single run," Creamer says.

"Additionally, it allows us to detect these amino acids at very low concentrations, even in highly salty samples, with a very simple 'mix and analyse' process." ®

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