Microwave digestion technology has unique advantages such as time and material savings, safety, low pollution, low blank value, low loss, easy implementation of automatic monitoring, etc. It has been widely used in the analysis of heavy metals in food, environmental samples, human and animal samples, agricultural products, Chinese herbal medicine samples, textiles, alloys, cosmetics, and mineral samples, especially in the analysis and detection of volatile elements. It can be used in conjunction with a variety of analytical instruments, including atomic absorption spectroscopy (AAS), atomic emission spectroscopy, atomic fluorescence (AFS), inductively coupled plasma mass spectrometry (ICP-MS), and other analytical methods.
Microwave digestion is an important and effective pretreatment method widely used in food testing, mainly for the pretreatment stage of heavy metal detection in samples such as meat products, aquatic products, dairy products, seasoning, and food packaging materials. Since most common foods are composed of organic compounds such as carbohydrates, a large amount of CO2 gas will be produced during the digestion process. In addition, nitric acid used for digestion will be reduced to produce NO2 gas, and the reagents and water themselves will also generate a certain vapor pressure when heated. Therefore, in most food digestion reactions, when the temperature reaches a certain level, the pressure within the closed reaction system will rapidly increase. Since there is high temperature and high pressure in the reaction process, microwave radiation power must be controlled when digesting food samples, and the equipment used must also have multiple pressure protection measures to prevent danger.
Many environmental samples are not completely digested by acid under atmospheric pressure. Herein lies the significance of an automated microwave digestion system. The high temperature and high pressure conditions achieved by using closed microwave digestion can solve this problem well. At the same time, some volatile elements contained in the sample during the digestion process are well enclosed in the digestion vessel and not easily lost. Therefore, microwave digestion technology has been widely used in the analysis of many environmental samples such as sewage, sludge, and soil.
With the development of modern medical theory and technology, the role of trace elements in the human body has been gradually revealed, so people pay more and more attention to the content of various trace elements in biological samples. For the determination of trace elements, common analytical methods include AAS, AFS, ICP-AES, etc. These testing methods usually require certain pretreatments of the samples, namely, using the acid digestion method to dissolve all trace elements in the sample organism and its interior into soluble salts. The traditional digestion method often cannot reach the corresponding reaction temperature, and the sample is difficult to completely digest. However, utilizing automated laboratory systems such as a closed microwave digestion instrument produces high-pressure and high-temperature conditions, improving digestion efficiency and quality. Therefore, with significant advantages over other traditional processing methods and the existence of a large demand, microwave digestion technology is becoming more and more widely used in the analysis of trace elements in biological samples, including Chinese herbal medicine samples, animal and plant tissue samples, agricultural products, and biological fluid samples.
In addition to the above-mentioned fields, microwave digestion technology has also been widely used in product analysis or quality control in other industries such as petroleum and petrochemicals, metallurgy and mining, cosmetics, toy manufacturing, and paint industry. Many samples in these industries are difficult to be completely digested using conventional methods during testing. The unique advantages of closed microwave digestion method show good results in handling this type of sample.