Continuous potentiometric titration analysis method for micromolecule carboxylic acid and amino acid

Abstract

The invention discloses a volumetric analysis method, in particular to a continuous potentiometric titration analysis method for micromolecule carboxylic acid and amino acid in aqueous solution. The weak jump is enhanced by converting the first derivative of a titration curve into a jump index by a curve of the jump index to titrant volume; the pH value of the solution is regulated below 2 by using a strong acid when in titration; then the titration is carried out by using standard alkali liquor; a first jump is generated when the solution is titrated to have the pH value of 3-3.5, which shows that the free strong acid is titrated; the titration continues until the pH value of carboxyl is 7.5-9.3 to generate a second jump; then the titration continues until the pH value of amino is 11-11.5 to generate a third jump; and the consumed standard alkali liquor between the two adjacent jumps respectively reflect the total amount of the free strong acid, the carboxylic acid and the amino acid. The method is simple and convenient to operate and rapid to determine and has reliable result and low analysis cost, can be popularized and applied to analyzing other complicated samples.

Description

technical field [0001] The invention belongs to the field of chemical analysis technology and relates to a capacity analysis method, in particular to a method for continuous potentiometric titration analysis of small molecule carboxylic acids and amino acids. Background technique [0002] Small molecule carboxylic acids such as formic acid, acetic acid, propionic acid, aconitic acid, citric acid, malic acid, succinic acid, oxalic acid, and lactic acid are common carboxylic acids. One of the characteristics of this type of acid is its carboxyl (-COOH) dissociation constant The pKa value is generally between 3 and 7; amino acids such as aspartic acid, glutamic acid, threonine, proline, histidine, tyrosine, valine and alanine, the characteristics of such acids One is its pK 2 (-N + h 3 ) is generally between 9 and 11. The existence and content of these organic acids have practical significance in production and life. [0003] At present, the methods for the determination o...

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Problems solved by technology

The problem with this method is that a large amount of formaldehyde needs to be added to the titration solution, which will have adverse effects on the analysis environment and operators. At the same time, due to structural differences, a small number of amino acids are unstable in combination with formaldehyde, such as the interaction between proline and formaldehyde. Finally, the generated compound is unstable, resulting in a low titration result, while tyrosine contains a phenolic structure, resulting in a high titration result

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