Method for detecting the content of phenol and cresol in high-purity ammonia

Abstract

The invention discloses a method for detecting the content of phenol and cresol in high-purity ammonia. The method comprises the following steps: utilizing phenol and cresol in ammonia to easily dissolve in chromatographic pure water and form a stable solution, and then adding a PNBA solution for esterification reaction; after 30 minutes, transferring 1mL of liquid in the upper part into a 2mL of automatic sampling bottle to be arranged in a liquid chromatogram automatic sampler, and detecting the content of phenol and cresol through a gradient elution experiment. The inner wall of a C18 reversed column is made of small silicone balls, the chromatographic column of an instrument is protected, the service life of the chromatographic column is prolonged, and a monitoring role is played for the production and internal control of high-purity ammonia. The method is used for detecting the content of phenol and cresol in high-purity ammonia and has the advantages of simplicity in sampling, simplicity and convenience in operation, low cost, high analysis speed, high detection precision, low method detection limit and short analysis cycle.

Description

technical field [0001] The invention relates to a method for detecting impurities in gas, in particular to a method for detecting the content of phenol and cresol in high-purity ammonia. Background technique [0002] 5N high-purity ammonia is a very important raw material in food additives. In our daily life, it is closely related to us and is almost everywhere. It can be said that without food additives, it is impossible to have the color, aroma and taste of food , shape and texture, etc., there is no our colorful life today. And ammonium glycyrrhizinate is the most common food additive we come into contact with in our daily life: dissolve glycyrrhizic acid powder in an organic solvent solution for reflux extraction, add ammonia gas or ammonia water, filter and dry to obtain ammonium glycyrrhizinate; ammonium glycyrrhizinate has anti-inflammatory properties. The effect of liver poisoning is an active ingredient extracted from the traditional Chinese medicine licorice, whic...

AI Technical Summary

Problems solved by technology

However, in the existing technology of the domestic additive industry, the monitoring and detection of phenol and cresol are not mentioned in the standards on ammonia

The phenol and cresol in high-purity ammonia are mainly derived from raw ammonia: hydrogen is one of the raw materials for the synthesis of raw ammonia, and hydrogen is produced by cracking natural gas, so the process of cracking and synthesis has not been well controlled. Generally speaking, the content of phenols is relatively low, and they all exist in the form of gaseous or gaseous macromolecules. At present, there is no special method to detect them. They can only be vaporized or adsorbed or dissolved in an appropriate way, and then reused. At the same time, ammonia is a corrosive gas, and the majority of technicians have a headache for it. They have been looking for a direct gas sampling method to detect phenol and cresol in ammonia, but the direct Injection can corrode, damage or even destroy chromatography and columns

Although direct sampling is relatively simple, it brings a great degree of corrosion, damage and even destruction to the chromatographic instrument and chromatographic column at the same time; because the materials of chromatographic instrument and chromatographic column are all stainless steel, and ammonia gas is very easy to Corrosion of stainless steel substances, causing fatal damage to the instrument

For a new instrument that is put into work, it usually takes more than three months to replace the chromatographic column and consumables, or even make the instrument unable to work in a few weeks. The maintenance usually costs more than 20,000 yuan each time, and a lot of time is wasted. Such a serious hampers our daily testing

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