useMicrowave digestion instrumentTemperature/pressure conditions for organic reaction

Carbohydrates, proteins, and lipids are the three fundamental components of biological and plant tissue samples. Protein materials rapidly decompose at around 150 ℃, while tristearin (carbon fatty acid ester) only shows the same decomposition at around 160 ℃. After 175 ℃, which organic bonds remain unbroken under this condition are the π bonds in the benzene ring, which are aromatic amino acids. The decomposition of organic matrix samples by nitric acid is not *, * decomposition can only be achieved using special reagents such as perchloric acid. But the use of such strong oxidants should be avoided. The decomposition temperature of organic samples varies from 140 ℃ to 180 ℃ depending on their weight. The critical temperature for the digestion of organic sample components with nitric acid is as follows:

Substance nitric acid digestion temperature (℃)

Starch carbohydrates at 140 ℃

Proteins 145 ℃~150 ℃

Carbohydrates at 150 ℃

Lipids, fats>160 ℃~165 ℃

Heavy oil, petroleum, asphalt>180 ℃~185 ℃

In the decomposition of biological and plant substrates, gas byproducts such as CO2 and NO2 can generate high pressure. The solubility of NO2 will suddenly change due to the influence of the total pressure in the container. NO2 gas slowly escapes without foaming, releasing smoke with NO2 characteristics. Then the solution transformed into a more familiar yellow brown color. The color change from green to yellow brown is caused by nitric acid digestion products.