More accurate tracking of sample origins from now on

A growing number of laboratories are discovering the advantages of isotope analysis
Research & Analysis
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25 March 2019

More and more laboratories are carrying out analytical measurement on isotopes, not surprising considering that isotope analysis can often offer unique insights. But, there’s a catch.

A quick refresher: isotopes are atoms from the same chemical element with the same number of protons, but a different number of neutrons in their atomic core. Two atoms with identical numbers of protons and different numbers of neutrons are considered two isotopes of the same element (Carbon-12 and Carbon-13, for instance). Among other things, the number of neutrons determines how stable the core is and, combined with the number of protons, the atomic mass. Most elements have multiple stable isotopes (between two and ten). Some isotopes are unstable (or radioactive), and some are stable.

In nature, an element’s isotopes will always be present in the same ratios. However, the distribution of isotopes of the same element can change if the elements have, for instance, varying geographical or synthetic origins. External factors, such as climate or geographical conditions, can additionally cause changes. By measuring the distribution of two stable isotopes of the same element and comparing this to other measurements, we can draw certain conclusions about the origins of the samples measured.

Fingerprint

“The distribution of stable isotopes in the same element (also known as the ratios) creates a sort of fingerprint,” explain Simon James, NWE Offer Deployment Manager at Air Liquide. “This can help us track the origins of food products and medicines, but the technology is equally useful in measuring the atmosphere for greenhouse gases, or geochemical measurements to optimise oil and gas drilling.”

“For accurate, consistent measurement of stable isotopes, it is absolutely essential that the employed measuring instrument be calibrated using a reliable reference. We can supply such references, exhibiting a specific traceable stable isotopes fingerprint, either as a single gas (such as CO2 or CH4) or as a composite gas mixture consisting of multiple components. With these gases, the user can reliably measure the concentration of the stable isotope compared to the concentration of the element’s most commonly occurring stable isotope (delta values). The gases are available in different cylinder sizes and are suitable for a variety of research applications.”

Genuine Italian olive oil?

“Isotope Ratio Mass Spectrometry (IRMS) can be used to determine the authenticity and quality of food products such as wine, honey, olive oil, cheese, meat and rice. That’s because the ‘fingerprint’ revealed by the isotope distribution (ratio) means that its source can be determined with confidence, facilitating fraud prevention.”

“Analyses of stable isotopes can also be employed in environmental research projects, for example to date groundwater, or determine landfill contamination, investigate the origins of nitrates in groundwater, conduct research into vegetation, and greenhouse gases in the atmosphere.”

Efficient oil and gas drilling

“Isotope analysis can generate significant savings for the oil and gas industry. By analysing hydrocarbons in rock formations and liquids we can determine their geological history. Isotope analysis can then function as a diagnostic tool to determine whether the oil or gas obtained from two different wells originates from the same compartment. The source’s production can then be optimised, reducing costly exploratory drilling.”

“The medical sector is also making increasing use of isotope analysis to identify, for example, the origin of particular medicines, and also for diagnostic testing through breath analysis. If such testing reveals deviations in the stable isotope distribution compared to the reference values, this could indicate a gastric disorder.”

The DIY approach

Theoretically, laboratories could develop their own reference materials, but the reliability and accuracy of these references might not be assured, and this approach could compromise the traceability of the measurements. The work is also complex and time-intensive.

Primary Reference Materials

“Our R&D departments have gone to great lengths to maximise the reliability of our reference materials. We are currently involved in a subsidised European project to develop ‘Primary Reference Materials’ in collaboration with nine partners, primarily institutes and universities. These will function as a metrological anchor for future measurements and calibrations.”

“Additionally, we have partnered with two of the leading OEMs who manufacture equipment used to measure stable isotopes. Within these partnerships, we supply standardised reference gases for specific measurements using their equipment.”

“We are also happy to share our expertise and R&D with laboratories to assist in resolving their analytical concerns.”

Feel free to contact Simon James for more information.

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