What to do if the total nitrogen detector is inaccurate during monitoring

Total nitrogen content is an important water quality detection index. In order to effectively detect the content of total nitrogen in water, online monitoring technology of total nitrogen has appeared. In the past, when my country's R&D and manufacturing technology was immature, it actively used foreign expensive monitoring instruments. Although the monitoring cost was greatly increased, it also achieved certain achievements. However, with the advancement of science and technology and the widespread use of total nitrogen online monitors, my country's technology in the manufacture of water quality monitoring instruments has been very mature, but there are still some areas worthy of improvement in application, because correct and standardized operations can ensure total nitrogen The correctness of monitoring results reduces the cost of monitoring and improves monitoring efficiency. The main problem in the online monitoring of total nitrogen is that the blank value of total nitrogen lower than ammonia nitrogen and K2S3O8 is unreasonable. Total nitrogen includes organic nitrogen and inorganic nitrogen. The online monitoring method for total nitrogen is to digest and oxidize water samples into nitrate-nitrogen. The method used for the online monitoring of total nitrogen is persulfate digestion-photometric method. Usually, total nitrogen includes ammonia nitrogen, so total nitrogen cannot be lower than ammonia nitrogen. However, in the total nitrogen online monitoring, the total nitrogen is lower than the ammonia nitrogen, which may be due to the environmental problems in the laboratory. The air often contains ammonia and ammonium salts, and both ammonia and ammonium salts are very soluble in water, so the ammonia nitrogen content will increase. An increase will cause errors in the measurement results, resulting in a situation where the total nitrogen is lower than the ammonia nitrogen. If the oxygen-containing compounds in K2S3O8 reach a certain level, the light absorption speed of the reagent blank will increase, thereby exceeding the light absorption value. Therefore, unreasonable deduction of K2S3O8 will directly cause errors in the entire water quality monitoring data. How to solve these problems encountered in online monitoring of total nitrogen in water quality? In the monitoring of total nitrogen, it often happens that in the determination of the same water sample, the water sample should be degassed immediately after digestion for 30 minutes, and the water sample tube should be shaken several times while it is hot, so that the NH3 gas in the gas phase can be converted into nitric acid by the hot K2S2O8 digestion. root. To solve the problem of K2S3O8 blank value, first determine that the test water is ammonia-free water, and cover it immediately after taking it; each bottle of K2S3O8 is only made of 6 reagent blanks, and the average value is taken as the blank value after the statistical test. Deduction; if the K2S3O8 blank is high, you can Use after purification, dissolve K2S2O8 in ammonia-free water at 50-60 degrees Celsius, cool it to room temperature naturally in a clean place without ammonia, put it in a refrigerator at about 4 degrees Celsius, filter out the crystals with a glass sand funnel, and use an infrared lamp to drying. If the nitrogen-containing compound is higher than 0.005%, the aforementioned recrystallization step must be repeated once. Since the traditional monitoring method cannot effectively detect whether the total nitrogen content of the water is unqualified or exceeds the standard in real time, the online monitoring equipment for total nitrogen has become the choice of many enterprises. Although there are certain problems in the online monitoring of total nitrogen, there are preventive measures and solutions for these problems. As long as we operate according to the standard steps, we can get accurate total nitrogen values.