阅读说明：本技术 有机溶剂沉淀法和分光光度法联用测定糖醇螯合钾螯合率的方法 (Method for determining chelating rate of sugar alcohol chelated potassium by combining organic solvent precipitation method and spectrophotometry ) 是由 颜冬云 崔玉照 牛军浩 聂兆广 刘可忠 谭慧婷 孙伟 李鹏超 于 2021-09-06 设计创作，主要内容包括：本发明属于螯合物螯合率测定技术领域,涉及一种有机溶剂沉淀法和分光光度法联用测定糖醇螯合钾螯合率的方法,具体步骤包括：(1)有机溶剂沉淀法分离纯化糖醇螯合钾,用乙醇和丙酮按一定比例混合的有机溶剂反复振荡提取,将糖醇螯合钾母液分离得到底层沉淀物；(2)分光光度法测定螯合率,用紫外分光光度计分别测定母液和底物的吸光度,计算出乙酸根含量,根据公式计算得到螯合率；发明人首次用混合有机溶剂实现了糖醇螯合钾母液中螯合态钾的分离提纯,分离效果好,纯度高；无需测定钾离子含量,仅需测定乙酸根含量即可,测定方法操作简单、快速,对实验设备及人员要求较低,满足于一般企业和实验室快速检测需要。(The invention belongs to the technical field of chelate rate determination, and relates to a method for determining a sugar alcohol chelated potassium chelate rate by combining an organic solvent precipitation method and a spectrophotometry, which comprises the following specific steps: (1) separating and purifying sugar alcohol chelated potassium by an organic solvent precipitation method, repeatedly oscillating and extracting by using an organic solvent mixed by ethanol and acetone according to a certain proportion, and separating a sugar alcohol chelated potassium mother solution to obtain a bottom-layer precipitate; (2) measuring the chelation rate by a spectrophotometry method, respectively measuring the absorbance of the mother solution and the substrate by an ultraviolet spectrophotometer, calculating the content of acetate, and calculating according to a formula to obtain the chelation rate; the inventor firstly uses the mixed organic solvent to realize the separation and purification of chelated potassium in the sugar alcohol chelated potassium mother solution, and has good separation effect and high purity; the content of potassium ions is not required to be measured, only the content of acetate is required to be measured, the measuring method is simple and quick to operate, the requirements on experimental equipment and personnel are low, and the requirements on quick detection of general enterprises and laboratories are met.)

1. A method for measuring the chelating rate of sugar alcohol chelated potassium by combining an organic solvent precipitation method and a spectrophotometry method is characterized by comprising the following specific operation steps:

(1) separation and purification of sugar alcohol chelated potassium by organic solvent precipitation method

Adding a proper amount of mixed organic solvent consisting of ethanol and acetone into the sugar alcohol chelated potassium mother liquor, placing the mixture into an oscillator, adjusting oscillation frequency and time, and separating to obtain white colloidal precipitate and supernatant; adding a proper amount of the mixed organic solvent into the bottom layer jelly again, placing the mixture in an oscillator, adjusting oscillation frequency and time, separating to obtain bottom layer precipitate and supernatant, repeating the operation until the content of acetate in the supernatant is unchanged, and finally obtaining the bottom layer jelly which is the sugar alcohol chelated potassium substrate;

(2) spectrophotometric determination of chelation rate

Respectively adding the same amount of the sugar alcohol chelated potassium mother liquor and the purified sugar alcohol chelated potassium substrate into a proper amount of sugar alcohol chelated potassium mother liquorIonized water with FeCl₃Measuring absorbance of the solution at 252nm wavelength with ultraviolet spectrophotometer, and calculating acetate content S_SubstrateAnd S_{Mother liquor}(ii) a The chelating rate of the sugar alcohol chelated potassium is calculated according to the following formula: chelation rate (%) ═ S_Substrate/S_{Mother liquor}×100％。

2. The method for measuring the chelating rate of the sugar alcohol chelated potassium by combining the organic solvent precipitation method and the spectrophotometry method according to claim 1, wherein the volume ratio of ethanol to acetone in the mixed organic solvent is 1:1-1: 1.5.

3. The method for measuring the chelating rate of the sugar alcohol chelated potassium by combining the organic solvent precipitation method and the spectrophotometry method as claimed in claim 1, wherein the sugar alcohol chelated potassium mother liquor is prepared from deionized water, sugar alcohol and potassium acetate, wherein the sugar alcohol includes but is not limited to one or more of sorbitol, mannitol or xylitol.

4. The method for measuring the chelating rate of potassium alditol chelate according to claim 1, wherein the amounts of both the potassium alditol chelate mother liquor and the potassium alditol chelate substrate used in step (2) correspond to each other.

The technical field is as follows:

the invention belongs to the technical field of chelate rate determination, relates to a detection method of sugar alcohol chelated potassium chelate rate, and particularly relates to a method for determining sugar alcohol chelated potassium chelate rate by combining an organic solvent precipitation method and a spectrophotometry method.

Background art:

potassium is one of mineral nutrient elements necessary for plant growth and development, and has an extremely important function in physiological and biochemical processes of crops. The sugar alcohol chelated potassium is a substance with a chelated ring generated by chelating reaction between sugar alcohol serving as a ligand and potassium ions, and the substance has the advantages of good stability, high utilization rate and the like, and has been applied to field crops and facility agriculture. As a novel fertilizer, the sugar alcohol chelated potassium has no national standard, the quality of the chelated potassium fertilizer on the market at present cannot be judged, and more, the organic matter and the inorganic sylvite are simply mixed and dissolved, so that the beads of fish eyes are mixed, or even if chelated, the chelating rate is unknown. The existing detection methods such as glucose gel filtration chromatography, organic solvent extraction, ultraviolet spectroscopy, spectrophotometry, XRD combined method and the like are mainly applied to the detection of the chelating rate of amino acid chelates, and the chelating central atoms are Ca in divalent state or trivalent state²⁺、Mg²⁺、Zn²⁺、Cu²⁺、Fe²⁺、Fe³⁺And the like. So far, no report on the detection method of the series of chelated potassium with the central ion in a valence state, such as the detection of the chelating rate of sugar alcohol chelated potassium, is available.

Chinese patent CN 108195968A discloses a detection method for determining amino acid chelate rate, which has the basic principle that after being heated and centrifuged, chelates are separated into precipitated chelate elements, soluble chelate elements and free metal ions, and are separated by using a gel chromatographic column under appropriate conditions, and then the contents of different forms of metal elements are determined by atomic absorption spectrometry, so as to calculate the amino acid chelate rate, which may cause chelate structure change in the heating and centrifuging process, and in addition, the operation has higher requirements on experimental equipment conditions, an atomic absorption spectrophotometer needs to be equipped, and the whole detection process is complex in operation, takes long time, and about 3-5 hours, increases the test cost, and is not suitable for analysis and test in common laboratories. Chinese patent CN 107286219 a discloses a method for determining the synthesis ratio of a trace element compound amino acid/small peptide chelate and rapidly estimating the chelating rate by using a combination of photometry and XRD. Chinese patent CN 108613939A discloses a method for detecting the chelation rate of small peptide microelement chelate, and the centrifugal speed of the patent in the operation process is as high as 12000r/min, so that the structure of the chelate is possibly damaged, and the detected chelation rate is less than the real chelation rate. The subject group discloses a separation and purification method of sugar alcohol chelated calcium in organic fertilizer (patent No. CN 110015945A), which adopts acetone as an extracting agent to separate free calcium ions and chelated calcium ions, but the method is not suitable for separation and purification of sugar alcohol chelated potassium, the sugar alcohol chelated potassium cannot be effectively separated by a single acetone extraction method, only partial precipitate is generated, the chelating rate of the sugar alcohol chelated potassium cannot be truly reflected, and the main reason is that the two elements have different valence states, and the structure difference of chelate formed after the two elements are combined with sugar alcohol is large.

The solubility of the chelated metal ions in organic solvents such as ethanol and acetone is low, but the non-chelated metal ions are easily dissolved in the organic solvents, so that the chelate can be separated and purified according to the principle, and the chelating rate of the chelate can be calculated by respectively measuring the chelated metal ions in the precipitate and the metal ions in the solution, and no report is found at present for effectively separating the sugar alcohol chelated potassium. However, the sugar alcohol in the sugar alcohol chelated potassium is a weak chelating agent, and the chelated structure is easily destroyed by high-speed centrifugation, so that the measurement result is inaccurate. After separation, the concentration of potassium ions is determined by EDTA coordination titration, so that the workload is inevitably increased, and if the chelation rate is determined by adopting an atomic absorption method or a liquid chromatography, the detection cost is high. Therefore, a convenient, rapid and accurate method for determining the chelating rate of the sugar alcohol chelated potassium is needed to be established, so that a technical basis is provided for optimizing the quality of the products and popularizing and applying the products.

Disclosure of Invention

The invention aims to find a method for detecting the chelating rate of sugar alcohol chelated potassium based on the combination of an organic solvent precipitation method and a spectrophotometry method, and the method has the advantages of high accuracy of the determination result, simple operation and easy application and popularization.

In order to achieve the purpose, the invention provides a method for measuring the chelating rate of sugar alcohol chelated potassium by combining an organic solvent precipitation method and a spectrophotometry method, which comprises the following operation steps:

(1) separation and purification of sugar alcohol chelated potassium by organic solvent precipitation method

Adding a proper amount of mixed organic solvent consisting of ethanol and acetone into the sugar alcohol chelated potassium mother liquor, placing the mixture into an oscillator, adjusting oscillation frequency and time, and separating to obtain white colloidal precipitate and supernatant; adding a proper amount of the mixed organic solvent into the bottom layer jelly again, placing the mixture in an oscillator, adjusting oscillation frequency and time, separating to obtain bottom layer precipitate and supernatant, repeating the operation until the content of acetate in the supernatant is unchanged, and finally obtaining the bottom layer jelly which is the sugar alcohol chelated potassium substrate;

(2) spectrophotometric determination of chelation rate

Adding the same amount of deionized water into a proper amount of sugar alcohol chelated potassium mother liquor and a purified sugar alcohol chelated potassium substrate respectively, and adding FeCl₃Measuring the absorbance of the solution by using an ultraviolet spectrophotometer under the wavelength of 252nm to calculate the content of acetate in different solutions; the chelating rate of the sugar alcohol chelated potassium is calculated according to the following formula: chelation rate (%) ═ S_Substrate/S_{Mother liquor}×100％。

In the formula: s_Substrate-acetate content (g) in sugar alcohol chelated potassium substrate;

S_{mother liquor}Acetate content (g) in the sugar alcohol chelated potassium mother liquor.

Further, the volume ratio of the ethanol to the acetone in the mixed organic solvent is 1:1-1: 1.5.

Further, the sugar alcohol chelated potassium mother liquor is prepared from deionized water, sugar alcohol and potassium acetate, wherein the sugar alcohol includes but is not limited to one or more of sorbitol, mannitol or xylitol.

Furthermore, the amount of the sugar alcohol chelated potassium mother liquor and the amount of the sugar alcohol chelated potassium substrate in the step (2) correspond to each other.

The main principle of the invention is as follows: the sugar alcohol chelated potassium has very low solubility in ethanol and acetone, while the potassium acetate and the sugar alcohol are easily dissolved in a mixed solution prepared by ethanol and acetone according to a certain proportion, and the chelated potassium and the non-chelated potassium are separated by utilizing the solubility difference of the potassium acetate and the sugar alcohol in the mixed organic solvent. The ratio of the chelating substrate potassium ion content to the mother liquor potassium ion content in the sugar alcohol chelated potassium acetate is approximately equal to the ratio of the chelating substrate acetate content to the mother liquor acetate content. Therefore, the chelating rate of the sugar alcohol chelated potassium can be represented by measuring the acetate content of the mother liquor and the substrate.

Compared with the prior art, the invention has the following advantages:

(1) the inventor firstly uses the mixed organic solvent to realize the separation and purification of chelated potassium in the sugar alcohol chelated potassium mother solution, and has good separation effect and high purity; the mixed organic solvent is prepared by mixing ethanol and acetone, and the raw materials are easily available; (2) the determination method is simple and quick to operate, has low requirements on experimental equipment and personnel, and meets the requirements on quick detection of enterprises and laboratories; (3) compared with the conventional method, the method does not need to measure the content of potassium ions, only needs to measure the content of acetate, and obviously reduces the economic cost; (4) provides a method for measuring the chelating rate of sugar alcohol chelated potassium, and can provide a basis for formulating the detection standard of the chelating rate of sugar alcohol chelates.

Description of the drawings:

FIG. 1 is a schematic diagram of a chelate mother liquor obtained by reacting different sugar alcohols according to the present invention with potassium acetate.

FIG. 2 is a diagram showing the separation and purification effects of different sugar alcohol chelated potassium according to the present invention.

The specific implementation mode is as follows:

the present invention will be described in further detail with reference to examples.

Example 1:

the embodiment relates to a method for detecting the chelating rate of potassium sorbate chelate by combining an organic solvent precipitation method and a spectrophotometry method, which comprises the following specific operation steps:

(1) sequentially adding 12 parts of deionized water, 27 parts of sorbitol and 5 parts of potassium acetate into a wide-mouth bottle, stirring in a heat-collecting constant-temperature magnetic stirrer, controlling the water temperature to be 65 ℃, the rotating speed to be 1000r/min and the reaction time to be 40min to obtain a clear and transparent sugar alcohol chelated potassium mother solution;

(2) mixing absolute ethyl alcohol and acetone according to the volume ratio of 1:1.25, and shaking up to prepare a mixed organic solvent;

(3) adding 1.0000g of the sugar alcohol chelated potassium mother liquor prepared in the step (1) and 10mL of the mixed organic solvent prepared in the step (2) into a centrifuge tube, sealing, placing in an oscillator, adjusting the oscillation frequency to 300r/min and the oscillation time to 40min, and pouring off the supernatant A_i，i＝1；

(4) Adding 10mL of the mixed organic solvent prepared in the step (2) into a centrifuge tube from which the supernatant is poured, sealing, putting the centrifuge tube into an oscillator again, adjusting the oscillation frequency to 300r/min, oscillating for 40min, and pouring out the supernatant A_iI is 2; repeating the above steps for 3 times, and removing supernatant A_iI is 3, 4, 5; the bottom colloidal precipitate is sugar alcohol chelated potassium;

(5) collecting the bottom colloidal precipitate of sugar alcohol chelated potassium generated in the step (4), diluting to 100mL with deionized water, shaking up, and adding FeCl₃As a color developing agent, the content S of acetate in the substrate is calculated by adopting an ultraviolet spectrophotometry at the wavelength of 252nm_Substrate(ii) a Weighing 1.0000g of sugar alcohol chelated potassium mother liquor prepared in the step (1), using deionized water to fix the volume to 100mL, shaking up, and using FeCl₃As color developing agent, at 252nm wavelength, calculating acetate content S in mother liquor by ultraviolet spectrophotometry_{Mother liquor}；

(6) Sugar was calculated according to the following formulaChelating ratio of alcohol-chelated potassium: chelation rate (%) ═ S_Substrate/S_{Mother liquor}X 100%, results are shown in table 1:

TABLE 1 results of organic solvent precipitation and spectrophotometry combined determination of potassium sorbate chelating rate

And (4) conclusion: as can be seen from Table 1, the results of the three sets of parallel tests are similar, which indicates that the spectrophotometry is suitable for the determination of the chelating rate of the chelate synthesized by using sorbitol as a chelating agent and potassium acetate.

Example 2:

the embodiment relates to a method for determining the chelating rate of potassium complex alditol chelate by using an organic precipitation method and a spectrophotometry method, which comprises the following specific operation steps:

(1) sequentially adding 12 parts of deionized water, 23 parts of sorbitol, 3 parts of mannitol and 5 parts of potassium acetate into a wide-mouth bottle, stirring in a heat-collecting constant-temperature magnetic stirrer, controlling the water temperature to be 65 ℃, the rotating speed to be 1000r/min and the reaction time to be 40min to obtain the clear and transparent sugar alcohol chelated potassium mother liquor.

(2) Mixing absolute ethyl alcohol and acetone according to the volume ratio of 1:1, and shaking up.

The procedure was the same as in example 1 except for the steps (1) and (2).

With FeCl₃The chelating ratio of this example was measured at a wavelength of 252nm by ultraviolet spectrophotometry as a color developing agent, wherein the chelating ratio (%) was S_Substrate/S_{Mother liquor}X is 100%; the results are shown in Table 2.

Table 2 results of organic solvent precipitation method and spectrophotometry method combined determination of chelating rate of potassium complex sugar alcohol chelate

And (4) conclusion: as can be seen from Table 2, the results of the three groups of parallel tests are similar, which indicates that the spectrophotometry is suitable for the determination of the chelating rate of the chelate synthesized by taking the complex sugar alcohol consisting of sorbitol and mannitol as the chelating agent and potassium acetate.

Example 3:

the embodiment relates to a method for determining the chelation rate of potassium xylitol chelate by combining an organic matter precipitation method and a spectrophotometry method, which comprises the following specific operation steps:

(1) sequentially adding 12 parts of deionized water, 23 parts of xylitol and 5 parts of potassium acetate into a wide-mouth bottle, stirring in a heat-collecting constant-temperature magnetic stirrer, controlling the water temperature to be 65 ℃, the rotating speed to be 1000r/min and the reaction time to be 40min to obtain clear and transparent sugar alcohol chelated potassium mother liquor;

(2) mixing ethanol and acetone at a volume ratio of 1:1.5, and shaking up.

The procedure was the same as in example 1 except for the steps (1) and (2).

With FeCl₃The chelating ratio of this example was measured at a wavelength of 252nm by ultraviolet spectrophotometry as a color developing agent, wherein the chelating ratio (%) was S_Substrate/S_{Mother liquor}X is 100%; the results are shown in Table 3.

TABLE 3 results of the organic solvent precipitation method and spectrophotometry method for determining the chelating rate of potassium xylitol chelate

And (4) conclusion: as can be seen from Table 3, the results of the three sets of parallel tests are similar, which indicates that the spectrophotometry is suitable for determining the chelating rate of the chelate synthesized by taking xylitol as the chelating agent and potassium acetate.

Example 4:

two methods for measuring the chelating rate of potassium sugar alcohol chelate, which are described in the present example: the method comprises the following specific operation steps of:

(1) sequentially adding 12 parts of deionized water, 23 parts of sorbitol, 3 parts of mannitol and 5 parts of potassium acetate into a wide-mouth bottle, stirring in a heat-collecting constant-temperature magnetic stirrer, controlling the water temperature to be 65 ℃, the rotating speed to be 1000r/min and the reaction time to be 40min to obtain the clear and transparent sugar alcohol chelated potassium mother liquor.

(2) Mixing ethanol and acetone according to the volume ratio of 1:1.25, and shaking up to obtain a mixed organic solvent;

(3) adding 1.0000g of the sugar alcohol chelated potassium mother liquor prepared in the step (1) and 10mL of the mixed organic solvent prepared in the step (2) into a centrifuge tube, sealing, placing in an oscillator, adjusting the oscillation frequency to 300r/min and the oscillation time to 40min, and collecting a supernatant A_i，i＝1；

(4) Adding 10mL of the mixed organic solvent prepared in the step (2) into a centrifuge tube from which the supernatant is removed, sealing, placing in an oscillator again, adjusting the oscillation frequency to 300r/min, oscillating for 40min, and collecting the supernatant A_iI is 2; repeating the above steps for 3 times to obtain supernatant A_iI is 3, 4, 5; the bottom colloidal precipitate is sugar alcohol chelated potassium;

(5) combining the supernatants A generated in the steps (3) and (4)_i，i＝1、2、3、4、5；

(6) Measuring the chelating rate by spectrophotometry, collecting the bottom colloidal precipitate sugar alcohol chelated potassium generated in the step (4), fixing the volume to 100mL by deionized water, shaking up, and adding FeCl₃As a color developing agent, the content S of acetate in the substrate is calculated by adopting an ultraviolet spectrophotometry at the wavelength of 252nm_Substrate(ii) a Weighing 1.0000g of sugar alcohol chelated potassium mother liquor prepared in the step (1), using deionized water to fix the volume to 100mL, shaking up, and using FeCl₃As color developing agent, at 252nm wavelength, calculating acetate content S in mother liquor by ultraviolet spectrophotometry_{Mother liquor}(ii) a The chelating ratio (%) of the sugar alcohol-chelated potassium was calculated according to the following formula: is equal to S_Substrate/S_{Mother liquor}×100％；

(7) The chelation rate was measured by ICP-AES method to prepare potassium standard series solutions having mass concentrations of 0. mu.g/mL, 1. mu.g/mL, 5. mu.g/mL, 10. mu.g/mL, 20. mu.g/mL, and 25. mu.g/mL, respectively. Then, measuring the emission intensity of each standard solution at the wavelength of 766.491nm by using a plasma emission spectrometer; drawing a standard curve by taking the mass concentration (mu g/mL) of the standard series solution potassium as an abscissa and the corresponding emission intensity as an ordinate; under the same conditions as the solutions of the measurement series, the solution obtained in the step (1) is measuredThe emission intensity of the potassium in the mother liquor and the supernatant obtained in the step (5) is checked out from the standard curve to find out the mass concentration M of the potassium in the mother liquor_{Mother liquor}(μ g/mL) and the mass concentration M of potassium in the supernatant_Substrate(μ g/mL) based on the chelation ratio (%) (1-M)_{Supernatant fluid}/M_{Mother liquor}) X 100%, calculating the chelation rate; a comparison of the two methods is shown in table 2:

TABLE 4 determination of chelating ratio (%)' of sugar alcohol-chelated potassium by spectrophotometric method and ICP-AES method

And (4) conclusion: as can be seen from Table 4, the result of measuring the chelating rate by the spectrophotometry is similar to the result of measuring the chelating rate by the ICP-AES method, and the error of the two methods is 0.81-4.22%, which indicates that the method for measuring the chelating rate by the spectrophotometry has higher accuracy and precision, is suitable for measuring the chelating rate of sugar alcohol chelated potassium in a common laboratory, and can effectively reduce the measuring cost of the chelating rate and improve the measuring efficiency.