Microwave digestion is an efficient sample preparation method that meets the requirements of modern instrumental analysis for sample pretreatment, with the advantages of fast and uniform heating, low reagent consumption, low blank values, and high energy efficiency. Especially in the analysis and detection of volatile elements, it can maintain the integrity of the sample and achieve high sample recovery rate.
According to the power emission mode, microwaves are divided into pulsed microwaves and non-pulsed microwaves. The traditional fixed power output characteristic is a switchable pulsed microwave, which is not only difficult to control, but may also directly affect the digestion effect.
The development of automated microwave digestion systems emphasizes on automatic power frequency conversion control and non-pulsed technology. This technology is hallmarked by automatic power modulation and non-pulsed microwave output, which eliminate the need for turning off the microwave emission during the digestion process. Its advantages are that it does not require turning off the microwave emission. Under continuous microwave emission conditions, the microwave power output is automatically changed linearly according to temperature and pressure feedback signals, adjusting the reaction state and controlling the temperature more accurately to ensure the safety and smooth progress of the experiment.
As a type of popular lab automation equipment, high-end microwave digestion instruments on the market generally use the following materials: the inner vessel uses TFM, the outer vessel uses aerospace composite materials, the lid uses PFA, and the pressure diaphragm uses PEEK.
Explosives (TNT, nitroglycerin, etc.), propellants, ignition chemicals, perchlorates, glycols (ethylene glycol, propylene glycol, etc.), aviation fuels, acetylene compounds, various ethers, ketones, short-chain alkanes, and so on. Do not use nitric acid to digest phenol, triethylamine, and animal fats.
After adding acid to the sample (especially unknown samples), do not immediately put it into the microwave digestion instrument. Observe the reaction situation. If there is severe reaction, it needs to be allowed to sit for a period of time. Some samples need to be soaked in acid overnight.
Do not put samples with sudden reactions and explosive components into the microwave sealed digestion system for digestion.
Do not use perchloric acid to digest oil samples and samples with high oil content.
The microwave digestion instrument should be placed on a sturdy and stable laboratory bench, and there should be no covering on the top and sides of the furnace, with a space of more than 20 centimeters. There should be a space of more than 15 centimeters on the back wall to ensure good ventilation.
It should be kept away from heat sources to avoid hot air and steam entering the microwave oven to cause malfunctions. It should also be far away from the tap water source to avoid the risk of electric shock due to water splashing.
Do not approach strong magnetic materials or appliances with magnetic properties, because external magnetic fields will interfere with the uniform distribution of magnetic fields in the furnace and reduce heating efficiency.
Other normal laboratory temperature and water and electricity conditions.