Sample dissolution has been a challenge for the analytical chemist. Dissolution of samples such as minerals, ores, rocks, soils, ceramics, oxides and coal test your patience as digestions take several hours or even days to complete under harsh conditions involving highly corrosive acids and heat.
Wet chemical digestions involve use of mineral acids conventionally in open systems. Closed microwave digestion systems offer several benefits which are highlighted below:
- Maximum heating temperature is limited by boiling point of the acid but can be raised to 250 – 300°C under pressurized conditions of closed systems
- Acid consumption is much less
- High extraction efficiency of analytes from sample matrix
- Minimum exposure of chemist to corrosive and pungent acid fumes
- Digestions generally take less than one hour in comparison to much longer time for open digestions
- 8 – 12 samples simultaneous digestions contribute significantly to increased laboratory productivity
- Due to closed system operation there is no loss of volatile elements during the digestion process and contamination from the environment is also eliminated.
The advantages offered far outweigh the initial investment and today several laboratories have introduced microwave digestion systems.
The sequence of images below will illustrate a typical digestion carried out using a commercial microwave digestion system.