阅读说明：本技术 一种氨基酸锌络合物中游离锌含量的检测方法 (Method for detecting content of free zinc in amino acid zinc complex ) 是由 吴彤彪 许详 黄志鹏 于 2020-07-19 设计创作，主要内容包括：本发明涉及一种游离锌含量检测技术领域,尤指一种氨基酸锌络合物中游离锌含量的检测方法,主要包括步骤：S1、称取氨基酸锌络合物样品加入烧杯中；S2、往烧杯中加入螯合剂溶液并搅拌,后进行过滤得到滤液A,加入螯合剂溶液对烧杯和滤纸进行重复三次冲洗,冲洗液与滤液A合并为总的滤液,并放置于锥形瓶中；S3、往滤液中添加乙酸溶液以调节溶液的酸碱度,并加入二甲酚橙指示剂；S4、往溶液中滴加六次甲基四胺溶液,然后采用乙二胺四乙酸二钠标准溶液滴定；S5、计算获得游离锌的百分含量；本发明高效检测甘氨酸锌、苏氨酸锌、赖氨酸锌中游离锌的含量,精确判定产品是否反应完全或者生成了多少锌水解产物,便于评价产品的优劣,以及指导工艺和生产。(The invention relates to the technical field of free zinc content detection, in particular to a method for detecting the content of free zinc in an amino acid zinc complex, which mainly comprises the following steps: s1, weighing an amino acid zinc complex sample and adding the amino acid zinc complex sample into a beaker; s2, adding a chelating agent solution into the beaker, stirring, filtering to obtain a filtrate A, adding the chelating agent solution to repeatedly wash the beaker and the filter paper for three times, combining the washing solution and the filtrate A into a total filtrate, and placing the total filtrate in a conical flask; s3, adding an acetic acid solution into the filtrate to adjust the pH value of the solution, and adding a xylenol orange indicator; s4, dropwise adding a hexamethylenetetramine solution into the solution, and then titrating by using an ethylene diamine tetraacetic acid standard solution; s5, calculating to obtain the percentage content of free zinc; the method has the advantages that the content of free zinc in the zinc glycinate, the zinc threonine and the zinc lysine is efficiently detected, whether the product completely reacts or how much zinc hydrolysate is generated is accurately judged, the quality of the product is conveniently evaluated, and the process and the production are guided.)

1. A detection method for the content of free zinc in an amino acid zinc complex is characterized by mainly comprising the following steps:

s1, weighing a sample: weighing an amino acid zinc complex sample and adding the amino acid zinc complex sample into a beaker;

s2, filtering to obtain filtrate: adding a chelating agent solution into the beaker in the step S1, stirring at normal temperature, filtering after stirring for 5min to obtain a filtrate A, then adding the chelating agent solution to repeatedly wash the beaker and the filter paper for three times, combining the washing solution and the filtrate A into a total filtrate, and placing the total filtrate in a 250mL conical flask;

s3, adjusting pH: adding an acetic acid solution to the filtrate of the step S2 to adjust the pH value of the solution, and adding a xylenol orange indicator;

s4, processing: dropwise adding a hexamethylenetetramine solution into the solution obtained in the step S3, and then titrating by using an ethylene diamine tetraacetic acid standard solution;

s5, calculating: the percentage of free zinc was calculated.

2. The method for detecting the content of free zinc in the zinc amino acid complex according to claim 1, wherein the sample of the zinc amino acid complex in step S1 can be lysine zinc hydrochloride, glycine zinc or threonine zinc, and the weighed amount is 0.4-0.8 g.

3. The method for detecting the content of free zinc in an amino acid zinc complex as claimed in claim 1, wherein the chelating agent of step S2 is an alkaline ligand comprising one or more of triethanolamine, ethylenediamine, and propylenediamine.

4. The method for detecting the content of free zinc in the zinc amino acid complex as claimed in claim 1, wherein the acetic acid solution of step S3 is a 1+16 acetic acid solution.

5. The method for detecting the content of free zinc in the zinc amino acid complex according to claim 1, wherein the xylenol orange indicator added in the step S3 is added in an amount of 5-6 drops.

6. The method for detecting the content of free zinc in the zinc amino acid complex as claimed in claim 1, wherein the pH value adjusted in step S3 is 5-7.

7. The method for detecting the content of free zinc in an amino acid zinc complex as claimed in claim 1, wherein the hexamethylenetetramine solution is added in step S4 until the solution is in a stable purple-red state, and the volume of 5mL is continuously added.

8. The method for detecting the content of free zinc in an amino acid zinc complex as claimed in claim 1, wherein the titration amount of the disodium ethylenediamine tetraacetic acid standard solution of the step S4 is determined by titration until the condition of the disodium ethylenediamine tetraacetic acid standard solution is changed from a purple state to a bright yellow state.

9. The method for detecting the content of free zinc in an amino acid zinc complex as claimed in claim 1, wherein the step S5 is calculated according to the following formula:

wherein 0.06538 is the mass in grams per millimole of zinc; c is the concentration of the standard solution of the disodium ethylene diamine tetraacetate, and the unit is mol/L; v is the volume of the standard solution of the disodium ethylene diamine tetraacetate, and the unit is mL; m is the mass of the sample in g.

Technical Field

The invention relates to the technical field of free zinc content detection, in particular to a method for detecting the content of free zinc in an amino acid zinc complex.

Background

Zinc glycinate, zinc threonine and zinc lysine are chelation reaction products of amino acid and a zinc source, zinc oxide, zinc hydroxide or basic zinc carbonate is required in the production process, and zinc hydroxide is generated due to zinc ion hydrolysis in the production process; among them, zinc glycinate, zinc threonine and zinc lysine are soluble in water, and insoluble zinc in the product is considered as an impurity. The conventional zinc detection method comprises a titration detection method and an instrument detection method, and both the titration method and the instrument detection method adopt a direct detection mode, but the detection method detects that the total zinc content is the total zinc content, the effective chelated zinc content in zinc lysine, zinc glycinate and zinc threonine cannot be effectively expressed, and insoluble zinc oxide, zinc hydroxide and the like can be detected; in general, in the process of dissolving or measuring a sample, zinc oxide and the like can be dissolved away by a reagent for detection, so that the detection result is inaccurate, and the problem of large error exists.

Because zinc glycinate, zinc threonine and zinc lysine are soluble in water, the chelated zinc and insoluble zinc source impurities can be filtered, separated and detected by utilizing the difference of solubility; but because zinc glycinate, zinc lysine and zinc threonine have hydrolysis phenomena to a certain degree in water solubility, particularly zinc lysine is obvious, and insoluble zinc hydroxide is generated after hydrolysis; this hydrolysis phenomenon interferes with the measurement if the filtration separation is carried out directly with pure water; therefore, in order to solve the above problems, it is necessary to adopt an applicable reagent or method to separate the original insoluble zinc source impurities such as zinc oxide, zinc hydroxide, zinc carbonate, etc. in the sample during the dissolution, filtration and separation of the sample, and the zinc glycinate, zinc lysinate, and zinc threonine will not be hydrolyzed, and the substances interfering the detection will not be generated, thereby overcoming the problems of inaccurate zinc measurement and incapability of evaluating the quality of the product.

Disclosure of Invention

In order to solve the above problems, the present invention discloses a method for detecting the content of free zinc in an amino acid zinc complex.

In order to achieve the purpose, the invention adopts the technical scheme that: a detection method for the content of free zinc in an amino acid zinc complex is characterized by mainly comprising the following steps:

s1, weighing a sample: weighing an amino acid zinc complex sample and adding the amino acid zinc complex sample into a beaker;

s2, filtering to obtain filtrate: adding a chelating agent solution into the beaker in the step S1, stirring at normal temperature, filtering after stirring for 5min to obtain a filtrate A, then adding the chelating agent solution to repeatedly wash the beaker and the filter paper for three times, combining the washing solution and the filtrate A into a total filtrate, and placing the total filtrate in a 250mL conical flask;

s3, adjusting pH: adding an acetic acid solution to the filtrate of the step S2 to adjust the pH value of the solution, and adding a xylenol orange indicator;

s4, processing: dropwise adding a hexamethylenetetramine solution into the solution obtained in the step S3, and then titrating by using an ethylene diamine tetraacetic acid standard solution;

s5, calculating: the percentage of free zinc was calculated.

Preferably, the amino acid zinc complex sample of step S1 can be lysine zinc hydrochloride, glycine zinc or threonine zinc, and the weighing amount is 0.4-0.8 g.

Preferably, the chelating agent of step S2 is an alkaline ligand, including one or more of triethanolamine, ethylenediamine, and propylenediamine, and most preferably triethanolamine.

Preferably, the acetic acid solution of step S3 is a 1+16 acetic acid solution.

Preferably, the amount of the xylenol orange indicator added in the step S3 is 5-6 drops.

Preferably, the pH value adjusted in step S3 is 5-7.

Preferably, the step S4 is to add hexamethylenetetramine solution until the solution is in a stable purple-red state, and to continue adding 5mL of solution.

Preferably, the titration amount of the disodium edta standard solution of step S4 is determined by titration to a state of bright yellow from a purple state.

Preferably, the step S5 is calculated according to the following formula:

wherein 0.06538 is the mass in grams per millimole of zinc; c is the concentration of the standard solution of the disodium ethylene diamine tetraacetate, and the unit is mol/L; v is the volume of the standard solution of the disodium ethylene diamine tetraacetate, and the unit is mL; m is the mass of the sample in g.

The invention has the beneficial effects that: the invention provides a new detection method to efficiently detect the content of zinc substances such as zinc threonine and zinc oxide in zinc lysine, so as to accurately judge whether the product is completely reacted or the content of the generated zinc hydrolysate, so as to evaluate the quality of the product and guide the process and the production.

Detailed Description

The following detailed description of the embodiments of the invention:

a detection method for the content of free zinc in an amino acid zinc complex mainly comprises the following steps:

s1, weighing a sample: weighing an amino acid zinc complex sample and adding the amino acid zinc complex sample into a beaker; the amino acid zinc complex sample can be lysine zinc hydrochloride, zinc glycinate, zinc threonine or other similar amino acid chelated zinc samples, and the weighing amount is 0.4-0.8 g;

s2, filtering to obtain filtrate: adding a chelating agent solution into the beaker in the step S1, stirring at normal temperature, filtering after stirring for 5min to obtain a filtrate A, then adding the chelating agent solution to repeatedly wash the beaker and the filter paper for three times, combining the washing solution and the filtrate A into a total filtrate, and placing the total filtrate in a 250mL conical flask; the chelating agent is an alkaline ligand, the chelating agent optimally selected in the embodiment is triethanolamine, and free zinc is chelated and protected by the strong binding effect of the chelating agent and metal ions to avoid hydrolysis;

s3, adjusting pH: adding an acetic acid solution into the filtrate obtained in the step S2 to adjust the pH value of the solution, wherein the acetic acid solution is a 1+16 acetic acid solution, the pH value is adjusted to 5-7, and adding 5-6 drops of a xylenol orange indicator;

s4, processing: dropwise adding hexamethylenetetramine solution into the solution obtained in the step S3 until the solution is in a stable mauve state, continuously adding 5mL of solution, and titrating by using an ethylene diamine tetraacetic acid standard solution until the mauve state becomes bright yellow;

s5, calculating: calculating to obtain the percentage content of the free zinc, and calculating according to a mathematical formula, wherein the mathematical formula is as follows:

wherein 0.06538 is the mass in grams per millimole of zinc; c is the concentration of the standard solution of the disodium ethylene diamine tetraacetate, and the unit is mol/L; v is the volume of the standard solution of the disodium ethylene diamine tetraacetate, and the unit is mL; m is the mass of the sample in g.

Determination method of total zinc:

weighing 0.4-0.8 g (accurate to 0.0002g) of amino acid zinc complex sample, adding the amino acid zinc complex sample into a 250mL conical flask, adding 5mL of acetic acid (1+16) solution and 30mL of pure water for dissolving, dripping 5 drops of xylenol orange indicator, dripping hexamethylenetetramine solution until the color of the stable mauve is changed into 5mL, and titrating by using an ethylene diamine tetraacetic acid disodium standard solution until the color of the mauve is changed into bright yellow to obtain the end point.

The percentage of total zinc (X2) was calculated as follows:

in the formula: 0.06538-grams of mass per millimole of zinc;

c-concentration of standard solution of disodium ethylenediaminetetraacetate (mol/L);

v-volume (ml) of sample consumed disodium EDTA standard solution;

m-mass (g) of the sample.