The challenge
Microfluidics is a promising avenue of exploration for new ways to handle radioactive materials at the microscale. However, a major limitation of microfluidic actinide analysis is the final determination, where known issues with conventional approaches such as UV visible light spectroscopy and X-ray fluorescence can lead to unreliable results.
Sponsored by AWE – Nuclear Security Technologies, a researcher from the University of Manchester has developed a system designed to overcome these limitations. The briefcase-sized device exploits lab-on-a-chip microfluidic technology for element separation and can be coupled with inductively coupled plasma mass spectrometry (ICP-MS) instrumentation for highly accurate analysis.
By exploiting fluid behaviour at a far smaller scale than conventional laboratory processes, with sample volumes in the range of micro to picolitres, it aims to provide an alternative approach to current analytical methods. As well as providing more rapid results and real-time output data, it has the potential to drive down costs, improve worker safety and reduce risks through automation, smaller sample volumes and less waste material.
Having tested a prototype with a simulated uranium sample, the researcher took advantage of NNUF-EXACT’s specialist facilities and expertise to validate the system using radioactive samples.
The research
With access to our unique combination of accessible equipment and a laboratory environment that can safely handle aqueous radioactive samples, the researcher was able to use the device to successfully perform mass spectrometry-based analysis of actinide materials, using as little as 20–50 microlitres of the active sample solution per analysis.
The research was conducted in two phases:
Phase 1
- This phase tested the on-line coupling of the microfluidic system with the ICP-QQQ-MS.
- UTEVA resin was used to separate uranium from other elements using different concentrations of nitric acid. An online dilution was also used to reduce the concentration of nitric acid to 2% (suitable for the ICP-MS system to handle).
- This demonstrated that the technology was capable of determining trace element concentrations in samples with high concentrations of uranium. This is very useful for nuclear forensics where they can be used to establish the origin of uranium materials such as ores and concentrates.
- The study made use of time-resolved ICP-MS analysis. This showed the potential for further applications such as chromatography method development, for example for screening new resins or optimising elution schemes.
Phase 2
- The study moved from separation of uranium only from trace elements to a more complicated separation scheme capable of separating uranium and plutonium at <fg amounts.
- This was done using a MC-ICP-MS system which allows for isotopic ratio information to be produced (for example, ²³⁵U/²³⁸U, ²³⁴U/²³⁸U, ²³⁸Pu/²³⁹Pu ²⁴¹Pu/²³⁹Pu). This is also important in nuclear forensics in determining the origin of a sample.
For more detailed technical information, please get in touch. You can also read about phase 1 methods and results in the published research paper.
Specialist facilities
- Unlike most laboratories, our ICP-MS system is available for use with radioactive solutions.
- Working with NNUF-EXACT opened up access to ICP-MS equipment across our network of supporting facilities. These included an ICP-QQQ-MS at GAU-Radioanalytical Laboratories, and an MC-ICP-MS at the University of Southampton’s Geochemistry department which allowed the researcher to measure plutonium and americium isotopes as well as uranium.
Expert input
The researcher benefited from the knowledge and experience of our specialist staff, who contributed to the experiment feasibility assessment and design, and advised on the proposal for user access funding.
Research support
- We took care of all radiological risk assessments and provided material handling support, allowing the researcher to focus on their work.
- As holders of a Euratom materials license and an Environment Agency radioactive substance permit, we arranged access to materials including certified uranium ore concentrate and radionuclide contaminated sediment.
- We also provided mixed radionuclide solutions prepared from certified tracers including one containing Pu-238, Pu-239, Pu-240, Pu-241 and Pu-242.
- We monitored the equipment for clearance after each visit, and produced, stored and disposed of aqueous radioactive solutions.
Flexible approach
We adapted our equipment to meet the researcher’s needs by fitting a bespoke sample introduction system to interface with ICP-MS.