What is microwave digestion, and why is it used?
Microwave digestion is a sample preparation technique commonly used in analytical chemistry, especially when performing metal and elemental analysis by ICP MS, ICP OES, or AAS.
The technique uses sealed, high pressure vessels and controlled microwave energy to rapidly break down solid or liquid samples in the presence of strong acids such as nitric acid or hydrochloric acid. This process converts the sample into a clear, homogeneous solution suitable for instrumental analysis.
How does microwave digestion work in practice?
Samples are typically weighed and placed into a digestion vessel along with a specific volume of acid determined by the sample mass. The vessel is sealed and placed inside a microwave digestion system which heats the mixture rapidly. As pressure and temperature increase, chemical reactions accelerate, causing organic matrices to oxidize and inorganic matrices to dissolve. Following digestion, the solution is cooled, vented and transferred for analysis.
What are the key advantages of Microwave Digestion?
Microwave digestion offers several advantages over traditional open vessel digestion methods:
- Faster digestion times with more complete matrix breakdown
- Reduced contamination risk due to sealed, closed‑vessel design
- Improved accuracy and reproducibility due to retention of volatile analytes
- Enhanced safety, limiting exposure to hazardous fumes and hot acids
- Precise control of temperature and pressure, delivering consistent, high‑quality sample preparation suitable for sensitive analytical techniques such as ICP MS, ICP OES, and AAS
Additional operational and throughput benefits include:
- Significantly reduced analyst time, with digestion cycles completed in ~30 minutes rather than overnight
- High-throughput capability, digesting up to 26 samples simultaneously in a single run
- Disposable vials, eliminating cleaning steps, reducing carryover risk, and improving efficiency
- Flexibility to digest multiple biological matrices together, including challenging samples such as bone and nail
Together, these benefits enable increased sample throughput and more efficient delivery of high quality data compared with alternative digestion approaches.
How does Arcinova use microwave digestion?
At Arcinova we ooperate a Milestone ultraWAVE digestion system that has been routinely and successfully applied in regulated studies for the digestion of complex biological matrices and elemental analysis.
In one GLP study, the ultraWAVE system was used to support the analysis of more than 600 tissue samples. The team efficiently digested and analyzed a broad range of tissues, including bone marrow, brain, gastrointestinal tract, liver, ovaries, testes, spleen, and uterus.
When is microwave digestion the right choice?
The alternative approach to using the ultraWAVE Digester is an overnight digest in a concentrated acid or base—which is labour intensive and takes time. Depending on the sample, an acid/base digest can also take longer than overnight, causing delays to sample analysis.
We recommend using the ultraWAVE digester in studies involving:
- Metallic nanoparticle solids
- Challenging biological matrices such as tissues, organs and fluids that are not easily digested
- Large clinical and non-clinical studies requiring high sample throughput
- Trace elemental impurity testing
Additional applications include:
- Pharmaceutical raw materials and drug products
- Food and nutritional analysis to determine trace metals, minerals and contaminants such as heavy metals
- Geological samples such as rocks and minerals
The ultraWAVE digester is a patented technology under Milestone.