Method for detecting total sulfite content in high-purity ammonia

Abstract

The invention discloses a method for detecting total sulfite content in high-purity ammonia. The method comprises the following steps of: adding purified water into a clean iodine flask, and directly introducing the high-purity ammonia into the iodine flask; heating obtained sample solution in a water bath at a temperature of 60+ / -5 DEG C to volatize a great quantity of ammonia, wherein the sulfite is dissolved in the water and does not volatilize, and cooling the solution to a lab temperature; adding a phenolphthalein indicator into the iodine flask, neutralizing excessive ammonia by hydrochloric acid solution, wherein the color of the solution is changed from pink to be colorless during the neutralization, adding hydrochloric acid solution into the iodine flask to ensure that the solution is acidic, converting the sulfite into sulphurous acid under the acid condition, carrying out redox reaction on the sulphurous acid and elemental iodine to generate sulfate; and calculating the mass of the total sulphurous acid through the mass of the consumed standard iodine solution, thus obtaining the total sulfite content in the high-purity ammonia. The method is used for detecting the total sulfite content in the high-purity ammonia and has the advantages of simplicity in sampling, easiness and convenience in operation, low cost, high analysis speed, high detection precision and low limit of detection limit.

Description

technical field [0001] The invention relates to a method for detecting impurities in gas, in particular to a method for detecting total sulfite content in high-purity ammonia. Background technique [0002] 4.5N 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, Taste, 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. Hepatotoxicity is an active ingredient extracted from the traditional Chinese medicine licorice, which can reduce alanine aminotransferas...

AI Technical Summary

Problems solved by technology

However, in the existing technology of the domestic additive industry, the monitoring and detection of the total sulfite content is not mentioned in the standards on ammonia

The sulfite substances 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 it is not well controlled in the cracking and synthesis processes; These by-products are also produced when the raw material ammonia is synthesized under high temperature and high pressure conditions; generally speaking, the sulfite content is relatively low, and they all exist in the form of gaseous or gaseous macromolecules, and there is currently no special method to detect them. , can only be quantified by appropriate methods such as vaporization or adsorption or dissolution, and then using detection equipment