Unlocking the secrets of resistant rocks and advanced materials
with ultraWAVE 3 microwave digestion system

The “Element and Isotopes” laboratory of the Central Analytical Research Facility (CARF) at Queensland University of Technology (QUT) produces high-precision analysis of trace elements and radiogenic isotopes in natural and engineered materials. Their research covers a wide range of samples, including rocks, soils, sediments, water, plants, insects, refractory materials, and even lithium battery components and organic matter. Since joining QUT in 2018, Prof. Balz Kamber has guided the analysis of digested rocks in CARF. Equipped with five ICP-MS and two ICP-OES instruments, the CARF “Elements and Isotopes” laboratories are designed for scientific excellence. It is a premium analytical facility dedicated to producing high-quality data that enables groundbreaking research. Even if this means fewer samples per year (about 300 difficult to digest geological samples), the emphasis is always on scientific value. A key part of this strategy is their clean laboratory, a small, HEPA-filtered room designed to maintain strict contamination control. Previously, all digestions had to be performed in this space using closed beakers on hotplates to avoid external contamination, leading to a resource and energy intensive method.

The lab’s primary challenge was digesting refractory materials, both geological and synthetic. Traditional methods like hotplate digestion with HF-HNO3 in closed Teflon beaker could not break down minerals such as zircon, rutile, chromite, or alumina. These minerals host critical elements like Zr, Ti, REEs, and Sn, which are increasingly important in global resource exploration and materials science. Additionally, due to safety regulations and operator risk, the lab opted not to use self-pressurizing ‘Parr’ style vessels, removing a conventional option for high-temperature, highpressure digestion. The physical clean fume hood space demands of hotplate digestion and Teflon cleaning also curtailed cleanroom use and protocols, making sample integrity difficult to maintain.

The introduction of single reaction-chamber (SRC) microwave technology marked a turning point. Chemical engineers in the adjoining lab suggested using their ultraWAVE 2, to test if it could provide a safer and more effective way to digest “refractory” rocks, based on the successful application of SRC for alumina, battery components and nanomaterials. The microwave SRC technology proved to be the ideal solution for refractor rocks and minerals due to its:

• Operational safety
• Compact footprint
• Ability to run in general laboratory
• Reduced energy and reagent consumption
• Ability to digest refractory materials like alumina

The lab recently upgraded to ultraWAVE 3, achieving improved robustness, ease of use, and higher sample capacity. The latest model allows digestion of up to 20 samples at 100 mg each, compared to 50 mg/ sample with the previous generation, significantly increasing productivity without compromising data quality. Another major advantage is vial cleaning. Microwave SRC built-in cleaning process allows PTFE vials to be cleaned directly in the system using sub-boiling distilled nitric and hydrofluoric acid, saving slow and laborious manual cleaning under fume hoods and reducing contamination risk. Finally, the sample workflow has been optimized: reagents are added inside the cleanroom, then the sealed rack is transported in contamination-free bags to the general lab for digestion in ultraWAVE 3, by eliminating the need for digestions to occur in the cleanroom itself.