Many laboratory procedures require the use of a microwave digester for sample preparation. The rationale for any microwave digestion process is based on the introduction of the samples into special transparent and closed vessels, in conjunction with the reagents required for testing. The sample is heated to temperatures ranging from 200° to 300° C so that it is partially or completely degraded.
Microwave digestion has many advantages over conventional open vessel digestion, however, the most important is that the one performed with microwave allows the more precise control of fundamental parameters, such as temperature, pressure and digestion time, to have a better management of the reaction that is occurring in the equipment.
Microwave digestion is a technique used to convert specific solid samples into suitable solutions for further analysis in spectrophotometry or polarography. It is based on the chemical digestion of the solid sample by using a liquid reagent, which is usually a mineral acid, then the sample together with the acid are capped in a closed container. When heating the closed container, the temperature increases rapidly, well above the boiling point of the acids, this allows the digestion process to accelerate and finish very quickly, in fact, a typical digestion lasts between 20 and 40 minutes, making this technique a very powerful tool.
Warming occurs by the interaction of microwaves with dipole ions and molecules in the sample. In the case of dipole molecules, an increase in the rotation of the molecules is generated, which in turn causes friction and generates heat. For ions, the microwave field increases vibrations, causing collisions between molecules and producing heat and energy. At the end of digestion, an aqueous solution is obtained, which can be analyzed with a spectrophotometer.
Necessary elements of a microwave digester
Because the digestion process aims to obtain a complete solution without loss or contamination, as well as a decomposition of the components of the sample to its most basic elements, aggressive reagents such as hydrochloric acid, hydrofluoric acid, nitric acid, sulfuric acid or hydrogen peroxide should be used. This means that the vessels to be used to include the sample must not react with the acids and must allow the transmission of microwave radiation.
The rapid heating of the samples in the closed containers also leads to a rapid increase in internal pressure, which is why, the microwave digestion containers must also be made of the material needed to withstand this. On the other hand, heating also generates heat-shedding reactions, which will lead to high pressures and temperatures.
Microwave digestion in the agricultural sector
In laboratories, microwave digestion is widely used in the mineralization of samples to subsequently analyze their most elemental components with the use of spectrophotometry techniques, making it necessary that the sample must always be in a liquid state. One of the industries where it is mostly used is in agriculture for environmental analysis.
In agriculture it is especially important because microwave digestion using acids such as nitric acid and mixing with hydrogen peroxide is very useful to analyze the most elementary components of soil samples. Knowing the components of certain types of soil is vital in the agricultural sector as farmers need to know which soils are suitable for planting. It is equally important because tissue analysis of plants and fruits can also be done.
Kalstein brand microwave digester
We at Kalstein, have microwave digesters useful for agricultural laboratories and any laboratory where the use of microwave digestion is vital. Our digesters are characterized by:
- Optional number of containers, up to 12 containers to meet different digestion requirements.
- Vertical design for uniform microwave distribution.
- Real-time monitoring of both the temperature and pressure of each vessel.
When you make your PURCHASE with us, you will get a high quality equipment since we are the MANUFACTURERS of each of these equipment, besides this, you will not find in other better PRICES than those offered by our company. To view our catalog of microwave digesters go to HERE