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Sample Pretreatment and Analysis

What happens to your samples at Aeon? Here is a brief outline of the process.

Pretreatment

Inspection
The sample quality and quantity are assessed and the course of pretreatment is planned.

Physical selection
A sub-sample is identified and selected from the submitted material. Non-representative bulk materials (rootlets, unwanted deposits, etc) are removed.

Chemical isolation
The sub-sample is cleaned and the carbon compounds of interest are chemically isolated and decontaminated. Carbonates are removed from organic samples; organic material and secondary carbonates are removed from carbonate samples. Soluble organic compounds are separated from insoluble ones. In some cases, specific compounds are individually selected. The sub-sample is then dried and weighed.

Carbon extraction
Adsorbed atmospheric carbon is removed. The carbon compounds in the sub-sample are converted to carbon dioxide by acid digestion or combustion. Different carbon compounds are preferentially combusted at specific temperatures. The carbon dioxide is then catalytically and cryogenically purified and its quantity is measured.

Graphitization
The purified carbon dioxide is reduced to a graphite (pure carbon) test sample.

Analysis

Radiocarbon analysis
The 14C/12C and 13C/12C isotope ratios in the graphite test sample are determined using a particle accelerator. The accelerator separates the different isotopes by mass, so the technique is called "Accelerator Mass Spectrometry," or AMS for short. The process is repeated several times. The data are averaged and normalized to international standards, and fractionation and blank corrections are applied.

Stable isotope analysis
A tiny portion of the extracted carbon dioxide is independently analyzed to determine its 13C/12C ratio with respect to the international standard (δ13CVPDB) .

 
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