The core reagents of Dumas combustion nitrogen analyzer mainly include combustion promoter, adsorbent, and carrier gas, and the selection of different reagents must follow strict standards. In terms of combustion accelerators, commonly used ones include tungsten trioxide, copper oxide, etc. When selecting, priority should be given to their oxidation ability and stability. High quality combustion promoters should be able to continuously release oxygen at high temperatures, ensuring complete combustion of the sample while avoiding impurities from decomposing and affecting the detection results. For example, tungsten trioxide not only has high oxidation efficiency, but also effectively reduces the combustion temperature of the sample and protects the internal components of the instrument. Adsorbents are mainly used to adsorb water and carbon dioxide generated during combustion processes. The commonly used anhydrous magnesium perchlorate has a good adsorption effect on water and is not easily reactive with other gases; Alkali lime can efficiently adsorb carbon dioxide, but attention should be paid to its strong hygroscopicity, and long-term exposure to air should be avoided to prevent failure. High purity helium or argon gas is usually used as the carrier gas, with a purity of over 99.999%. Excessive impurity content can interfere with the detection of nitrogen elements, resulting in biased results.

There are many key precautions during the use of reagents. Firstly, the amount of reagents added should be strictly controlled according to the instrument manual and experimental requirements. Adding too little combustion promoter can lead to incomplete combustion of the sample, while adding too much may result in excessive residue blocking the pipeline; Insufficient adsorbent addition can affect impurity adsorption efficiency, while excessive addition can increase gas flow resistance. Secondly, reagent replacement should be timely. When the color of the adsorbent changes significantly, such as anhydrous magnesium perchlorate changing from white to pink, it indicates that it has lost its adsorption capacity and needs to be replaced immediately; After long-term use, the activity of combustion accelerators will decrease, and they generally need to be replaced regularly after testing a certain number of samples. In addition, contamination should be avoided when adding reagents, and the addition tools should be cleaned and dried in advance to prevent the introduction of impurities that may affect the detection results.

The storage and management of reagents are equally important. All types of reagents should be stored by category, and combustion promoters should be stored in a dry and ventilated environment to avoid moisture; Adsorbents should be sealed and stored to prevent premature adsorption of moisture and carbon dioxide from the air; Gas cylinders should be kept away from sources of fire and high-temperature environments, and fixed and used according to regulations. At the same time, laboratory personnel should take personal protective measures during the operation, wearing gloves, goggles and other protective equipment to avoid contact with the skin and inhalation of reagents into the respiratory tract.