Embedding matrices to extend the shelf-life of reference materials 2: Carboxymethyl Cellulose

Volume: 67, December 2025, pages 2-17

Authors: Ana María Sánchez Hernández^a,*, Ramon Carlos Marquez^a, Kalman Toth^b, Buda Razvan^a, Nidhu Banik^a, Jeroen Bauwens^b, Renáta Buják ^c, Rožle Jakopič ^b, Vasiliki Exarchou ^b, Oliver Dieste-Blanco ^d, Evelyn Zuleger ^a, Yetunde Aregbe ^b

^a _{European Commission, Joint Research Centre (JRC), Karlsruhe, Germany}
^b _{European Commission, Joint Research Centre (JRC), Geel, Belgium}
^c _{International Atomic Energy Agency, IAEA Laboratories, Seibersdorf, Austria}
^d _{European Commission, Directorate General ENER, Luxembourg, Luxembourg}
 

Abstract: Large-sized dried (LSD) spikes are reference materials used in nuclear safeguards to accurately determine nuclear material inventories by Isotope Dilution Mass Spectrometry, which need to keep dried actinides stable in their vessel. For about 20 years, a solvent-cast film made of cellulose acetate butyrate (CAB) has been used to embed the dried material. This study proposes a new approach with a different embedding material to improve the mechanical properties of the LSD spikes and, therefore, extending their shelf-life. Furthermore, this approach increases the current capacity of the LSD spikes to embed actinides and, thus, to produce these certified reference materials with a broader range of uranium and plutonium amounts.
The new embedding material used to preserve the LSD spikes was prepared using a cellulose-based biodegradable polymer called carboxymethyl cellulose (CMC). The initial form of the matrix, including the actinide material, is foamy, although, with time it may become a viscous resin. Several tests and analyses were performed in spikes containing different amounts of uranium and plutonium to test the embedding matrix, its mechanical properties, ageing and to determine the shelf-life. It was demonstrated that LSD spike certified reference materials embedded in a CMC matrix have a guaranteed extended shelf-life of at least eight years, provided the protocols for preparation are carefully respected.

Keywords: Carboxymethyl Cellulose (CMC), Certified Reference Material (CRM), Large-sized dried (LSD) spike; Embedding matrix, Isotope Dilution-Thermal Ionisation Mass Spectrometry (ID-TIMS)

Reference guideline: Sánchez Hernández, A.M., Marquez, R.C., Toth, K., Razvan, B., Banik, N., Bauwens, J., Buják, R., Jakopič, R., Exarchou, V., Dieste-Blanco, O., Zuleger, E., Aregbe, Y., ( 2025, December). Embedding matrices to extend the shelf-life of reference materials 2: Carboxymethyl Cellulose, ESARDA Bulletin - The International Journal of Nuclear Safeguards and Non-proliferation, 67, 2-17. https://doi.org/10.3011/ESARDA.IJNSNP.2025.1