CN115561186A - Method for determining glucose in lithium-ion electrolytic copper foil electroplating solution - Google Patents

Abstract

The invention discloses a method for measuring glucose in lithium battery copper foil electroplating solution, which comprises the following steps: sample pretreatment, copper, nickel, iron, zinc measurement, glucose measurement, by optimizing the amount of phenol added, the amount of sulfuric acid added, significantly Based on the effects of color temperature and color development time on the absorbance of glucose, a method for the determination of glucose content in lithium battery copper foil plating solution was established. The optimization results are as follows: take 2.0mL of lithium battery copper foil electroplating solution, add 0.8mL of phenol and 7.0mL of sulfuric acid, develop color in a water bath at 50°C for 15 minutes, take out the cold water bath for 45 minutes, cool to room temperature, and measure the absorbance at an absorption wavelength of 490nm . Under optimal conditions, the linear correlation between glucose concentration and absorbance was good (r=0.9995), the standard addition recovery was 100.12%, the RSD was 0.76%, the precision RSD was 0.01%, and the repeatability RSD was 0.04%. The method of the invention can meet the requirements for measuring the glucose content in the lithium battery copper foil electroplating solution, and has accurate measurement results, small system errors, simple pretreatment process, and low uncontrollable factors.

Description

A method for the determination of glucose in lithium battery copper foil electroplating solution

technical field

The invention belongs to the technical field of measuring glucose content in an electroplating solution, and in particular relates to a method for measuring glucose in a lithium battery copper foil electroplating solution.

Background technique

The electroplating solution is a liquid that can increase the current density range of the metal cathode, improve the appearance of the coating, and improve the oxidation resistance of the solution. The chromic anhydride-glucose electroplating solution has been recognized by many copper foil manufacturers because of its simple process, no need for electroplating and easy operation. The chromic anhydride-glucose electroplating solution uses chromic anhydride, glucose and water as the main raw materials. Glucose is highly hydrophilic and rich in hydroxyl groups, which can absorb oxygen ions on the surface of copper foil and saturate the chemical affinity of the copper foil surface. Thereby passivation of copper foil is achieved. The Cr3+ and Cr6+ in the chromic anhydride aqueous solution can oxidize the copper on the surface of the copper foil to form a dense and well-covered copper salt, thereby changing the physical form and chemical structure of the copper foil. The glucose solution in the passivation solution has a certain passivation and anti-oxidation effect. Adsorption of oxygen ions on the surface of glucose is a prerequisite for the formation of an excellent passivation film. Glucose and chromic anhydride have a synergistic effect. First, the adsorption film formed by glucose, and then It is a phase-forming film of chromium. In lithium-ion batteries, copper foil is the most ideal cathode current collector material, so people's requirements for the quality of copper foil and the control of copper foil are becoming more and more stringent. Copper foil surface passivation process control is a key link in the production process. Too high or too low concentrations of glucose and chromic anhydride will affect the quality of copper foil, so controlling the concentration of glucose in the passivation solution is the key to measure the quality of copper foil.

The methods for determining glucose include: oxidation-reduction titration, iodine starch system fading photometry, mid-infrared attenuated total reflection method, HPLC method, glucose oxidase method, iodometric method, optical rotation method, and colorimetric method. Monosaccharides other than glucose will also interfere with the measurement results, and the system error is large. Glucose oxidase method and iodometric method to prepare standard titration solution take a long time, complicated operation, low glucose oxidase activity, and many uncontrollable factors. The concentration, wavelength and temperature of glucose in the polarimetry have great influence on the accuracy of the determination results. The HPLC method has high precision, but it is expensive, complicated to operate, time-consuming, and has high requirements for experimental conditions and equipment. The colorimetric method only needs an ultraviolet spectrophotometer to measure, and the instrument operation is simple and quick, and the accuracy is high. Therefore, it is necessary to develop a method for the determination of glucose in lithium battery copper foil plating solution with accurate measurement results, small system error, simple pretreatment process and low uncontrollable factors.

Contents of the invention

The object of the present invention is to provide a method for measuring glucose in lithium battery copper foil electroplating solution with accurate measurement results, small system error, simple pretreatment process and low uncontrollable factors.

In order to achieve the above object, the technical solution adopted in the present invention is: a method for measuring glucose in lithium battery copper foil electroplating solution, comprising the following steps:

A. Sample pretreatment

(1) Adjust the pH value of the solution

Put the electroplating solution with a volume of 20mL in a 50mL beaker, use 0.1mol/L sodium hydroxide solution and 0.1mol/L sulfuric acid solution as regulators, monitor the pH value of the solution with a pH meter, and stir while adjusting to make it evenly mixed , so that the pH of the solution reaches 3.5;

(2) Extraction of copper ions in the electroplating solution

With the ratio of water phase: oil phase as 1: 2, extract the copper ions in the electroplating solution, measure the regulating solution in 5mL step (1) in the separatory funnel, add 10mL30% ZJ988 extractant, shake for 5min, Stand still for 10 minutes, take the water phase for later use;

(3) Preparation of sample solution

Measure 0.5mL of the extract in step (2), put the extract in a 100mL volumetric flask, add deionized water to dilute to the mark, mix well and set aside;

B. Determination of copper, nickel, iron and zinc

Turn on the main engine of the atomic absorption spectrophotometer and the hollow cathode lamp detector to preheat for 15 minutes. At the same time, set the element detection parameters, turn on the air acetylene, air compressor and exhaust box in turn, and ignite after everything is ready, follow the prompts in order Carry out standard solution calibration curve drawing and measure the absorbance of metal ions in the electroplating solution, then calculate the metal ion content in the electroplating solution according to the linear regression equation of the standard solution, measure in parallel 3 times;

C. Determination of glucose

Use the phenol-sulfuric acid method to develop the color of the sample solution, measure glucose standard solution 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6mL, put them into 25mL stoppered colorimetric tubes respectively, add water to 2.0mL, and Take 2.0mL of the sample solution in step (3), and use distilled water as a reference at the same time; add 0.8mL of 6% phenol solution and shake well, immediately add 7mL of concentrated sulfuric acid solution, leave it at room temperature for 5min, and then put it in a room with a temperature of 50°C Develop color in a hot water bath for 15 minutes, then place it in a cold water bath for 45 minutes, and cool to room temperature; measure the absorbance under a UV-Vis spectrophotometer with a wavelength of 490 nm, draw a regression equation and calculate the glucose content in the sample;

D. Calculation of results

Metal ion content is calculated according to formula (1):

In the formula:

X - the content of the analyte in mg/mL;

Cx—mass concentration of any metal ion in the sample, mg/L;

D—sample dilution factor;

The extraction rate is calculated according to formula (2):

In the formula:

R——extraction rate, %;

C0, Ce—concentration of the ion to be measured in the solution before and after extraction, mg/L;

Glucose content is calculated according to formula (3):

In the formula:

m——sample pipetting volume, mL; 1000——conversion factor;

CA - mass concentration of glucose in the sample, μg/mL;

V——sample constant volume, mL;

The recovery rate of standard addition is calculated according to formula (4):

In the formula:

P——recovery rate of standard addition, %;

C1—sample concentration before standard addition, mg/mL;

C2—sample concentration after standard addition, mg/mL;

C3——scaling amount, μg/mL.

The beneficial technical effect of the present invention is:

1. The present invention uses the phenol-sulfuric acid method to measure the absorbance of the glucose in the electroplating solution after color development, and calculates the glucose content through a regression equation. The instrument is easy to operate and has high accuracy.

2. By measuring the content of copper, zinc, iron and nickel ions in the electroplating solution, explore the influence of metal ions on the determination of glucose content, and avoid the interference of residual metal ions on the determination of glucose content.

3. By optimizing the addition of phenol and sulfuric acid, the best color development time and temperature, and doing single factor experiments and response surfaces, the best method conditions for the determination of glucose content in lithium battery copper foil plating solutions were obtained.

4. The present invention starts from the preparation method of the copper foil electroplating solution and the copper foil passivation treatment process, analyzes the basic components of the electroplating solution and the substances that may be brought in after electroplating copper, and explores the method for measuring the glucose content in the electroplating solution. Best way. The establishment of this method is beneficial for enterprises to better monitor the concentration of glucose in the electroplating solution during the copper foil electroplating process, and prevent the glucose concentration from being too high or too low from affecting the quality of copper foil. It has good development prospects and practical application value.

Description of drawings

Fig. 1 is absorbance-wavelength curve;

Fig. 2 is glucose standard working curve;

Fig. 3 is the influence of phenol addition on absorbance;

Fig. 4 is the impact of sulfuric acid addition on absorbance;

Figure 5 is the influence of color developing time on absorbance;

Figure 6 is the influence of color temperature on absorbance;

detailed description

The present invention will be further described below in conjunction with examples, and examples include but do not limit the protection scope of the present invention.

Below in conjunction with specific example, further elaborate the present invention. These examples are only used to illustrate the present invention, and do not limit the application scope of the present invention. Methods not specified in the examples are generally carried out under conventional conditions or as suggested by the manufacturer. In addition, any similar detection content or material can be used in the present invention.

1. Instruments and reagents

Instrument name: UV-Vis spectrophotometer, atomic absorption spectrophotometer, water bath, electronic balance, electric blast drying oven, pH meter;

Reagent name: glucose C ₆ H ₁₂ O ₆ , phenol C ₆ H ₆ O, sodium hydroxide NaOH, sulfuric acid H ₂ SO ₄ , ZJ988 extractant, kerosene, thiourea H ₂ NCSNH ₂ , copper single element standard solution, zinc single element Element standard solution, iron single element standard solution, nickel single element standard solution.

2. Instrument testing conditions

2.1 Determination conditions of atomic absorption spectrophotometer

The working conditions for measuring copper, nickel, iron and zinc ions in the electroplating solution by atomic absorption spectrophotometer are shown in Table 2-1 and 2-2.

Table 2-1 Working conditions of atomic absorption spectrophotometer

Table 2-2 Working Conditions of Hollow Cathode Lamp

2.2 Measurement conditions of ultraviolet spectrophotometer

The measurement conditions of the ultraviolet photometer used to measure the glucose content in the electroplating solution are shown in Table 2-3.

Table 2-5 Working Conditions of UV Spectrophotometer

3. The assay method of glucose in lithium battery copper foil electroplating solution, comprises the following steps:

3.1 Sample pretreatment

3.1.1 Adjusting the pH of the solution

Put the electroplating solution with a volume of 20mL in a 50mL beaker, use 0.1mol/L sodium hydroxide solution and 0.1mol/L sulfuric acid solution as regulators, monitor the pH value of the solution with a pH meter, and stir while adjusting to make it evenly mixed , so that the pH of the solution reaches 3.5;

3.1.2 Extraction of copper ions in the electroplating solution

With the ratio of water phase: oil phase as 1: 2, extract the copper ions in the electroplating solution, measure the regulating solution in 5mL step (1) in the separatory funnel, add 10mL30% ZJ988 extractant, shake for 5min, Stand still for 10 minutes, take the water phase for later use;

3.1.3 Preparation of sample solution

Measure 0.5mL of the extract in "3.1.2" into a 100mL volumetric flask, add deionized water to dilute to the mark, mix well and set aside.

3.2 Determination of copper, nickel, iron and zinc

3.2.1 Determination of copper, nickel, iron and zinc

Accurately pipette 0.5mL of the original electroplating solution into four 100mL volumetric flasks, add deionized water to dilute to the scale, and then turn on the main engine of the atomic absorption spectrophotometer and the hollow cathode lamp detector to preheat for 15min, at the same time Set the element detection parameters, turn on the switch of air acetylene, air compressor and exhaust box in turn, ignite after everything is ready, follow the prompts to draw the calibration curve of the standard solution and measure the absorbance of metal ions in the plating solution, and then perform linear regression according to the standard solution The equation is used to calculate the metal ion content in the electroplating solution, and the parallel measurement is performed 3 times; the linear regression equation is shown in Table 3-1.

Table 3-1 Linear regression equation

It can be seen from Table 3-1 that in the standard solution of 0-50 mg/L, the linear equations of Cu, Ni, Fe and the absorbance have a good linear relationship; in the standard solution of 0-1.0 mg/L, the linear equation of Zn and the absorbance The linear relationship is good.

3.2.2 Determination results of copper, nickel, iron and zinc

Metal ion content is calculated according to formula (1):

In the formula:

X - the content of the analyte in mg/mL;

Cx—mass concentration of any metal ion in the sample, mg/L;

D—sample dilution factor;

Each ion was measured in parallel three times, the metal ion content, average content and SD value, the measurement results are shown in Table 3-2.

Table 3-2 Measurement results

It can be concluded from Table 3-2 that the average content of copper ions in the original electroplating solution is 113 mg/L, and the RSD is 2.06%, while the contents of nickel, iron and zinc ions are not detected, indicating that the copper ion content in the original electroplating solution is relatively high , nickel, iron and zinc ions were so low that they were not detected.

3.2.3 The influence of Cu ²⁺ on the determination results of the method

From the measurement results in Table 3-2, it can be seen that the electroplating solution contains some copper ions, and the remaining part of Cu ²⁺ in the electroplating solution will react with concentrated H ₂ SO ₄ to form copper sulfate, which may affect the absorbance when measuring the glucose content in the sample. According to the method under "3.1.2", the Cu ²⁺ in the electroplating solution is extracted, the method under "3.2.2" measures the Cu ²⁺ content, and the extraction rate is calculated according to the formula (2), and the extraction conditions And the measurement results are shown in Table 3-3.

Extraction rate calculation:

In the formula:

R——extraction rate, %;

C ₀ , Ce—concentration of the ion to be measured in the solution before and after extraction, mg/L;

Table 3-3 Extraction conditions and measurement results

It can be seen from Table 3-3 that after using ZJ988 to extract copper ions in the electroplating solution, the extraction rate of copper ions is 96.91%, which shows that the extraction conditions have a better effect on the extraction of copper ions in the electroplating solution, and the extraction rate is higher.

3.3 Determination of glucose

Use the phenol-sulfuric acid method to develop the color of the sample solution, measure glucose standard solution 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6mL, put them into 25mL stoppered colorimetric tubes respectively, add water to 2.0mL, and Take 2.0mL of the sample solution, and use distilled water as a reference; add 0.8mL of 6% phenol solution and shake well, immediately add 7mL of concentrated sulfuric acid solution, leave it at room temperature for 5min, and then put it in a hot water bath with a temperature of 50℃. After coloring for 15 minutes, put it in a cold water bath for 45 minutes, and cool it down to room temperature; measure the absorbance under a UV-Vis spectrophotometer with a wavelength of 490 nm, draw a regression equation and calculate the glucose content in the sample.

3.3.1 UV detection wavelength optimization

Accurately pipette 2.0mL each of the electroplating solution and 5μg/mL glucose standard solution into a 25mL stoppered colorimetric tube, develop color according to the experimental method "3.3", use distilled water as a blank, and scan with 400-800nm ultraviolet-visible spectrum , Determination of the maximum absorption wavelength, the results are shown in Figure 1.

It can be seen from Figure 1 that the maximum absorption wavelength of glucose in the standard solution and the electroplating solution is 490nm, so the optimum absorption wavelength is 490nm.

3.3.2 Ultraviolet determination of glucose standard curve and linear range

Carry out glucose solution preparation and color development according to "3.3", measure the absorbance at the absorption wavelength of 490nm, take the glucose concentration as the abscissa, and the absorbance as the ordinate, draw the standard working curve of glucose, as shown in Figure 2. The fitting results are: y=0.01336x+0.0365, r=0.9995. The results show that within the glucose concentration range of 5.0-30 μg/mL, the linear relationship between the glucose standard solution concentration and the absorbance is good.

3.4 Optimization of conditions for the determination of glucose by phenol-sulfuric acid method

3.4.1 Effect of phenol addition on absorbance

The effect of different phenol additions on the absorbance is shown in Figure 3. Add phenol solution with a concentration of 6%, and the amount added increases from 0.2mL to 1.0mL. When the amount of phenol added reaches 0.8mL, the absorbance reaches 0.237 at the highest, and when it reaches 1.0mL, the absorbance of the solution gradually decreases. is optimal.

3.4.2 Effect of sulfuric acid addition on absorbance

The results of the influence of different sulfuric acid additions on the absorbance are shown in Figure 4. When the addition of concentrated sulfuric acid is 1.0-9.0mL, the absorbance of the solution first decreases and then rises to 7.0mL, which is the maximum value. When the addition is 9.0mL, the solution The absorbance begins to decrease. If too little sulfuric acid is added, the hydrolysis of glucose will be incomplete, resulting in a decrease in absorbance, and excessive addition will make the furfural derivatives unable to maintain stability, resulting in a decrease in absorbance during hydrolysis. Therefore, 7.0mL was selected as the optimal dosage.

3.4.3 Effect of color development time on absorbance

The effect of different color development time on the absorbance is shown in Figure 5. When the color development time was 10-30 minutes, the absorbance first increased and then decreased, and became stable after 25 minutes. When the color development time was 15 minutes, the absorbance was the highest. Therefore, the optimal color development time was determined to be 15min.

3.4.4 Effect of color temperature on absorbance

It can be seen from Figure 6 that the absorbance of the solution increases gradually at 30-50°C, the absorbance of the solution shows an increasing trend at 30-50°C, the absorbance reaches the maximum at 50°C, and gradually decreases at 50-100°C. Therefore, 50°C is selected as the best color development temperature.

3.5 Best optimization conditions

According to the results of response surface analysis, it is concluded that the phenol-sulfuric acid method is used to analyze the color development of glucose in the electroplating solution. The glucose content in the sample was 3.1028mg/mL. After considering the actual operation situation, the actual method parameters were adjusted to be 0.80mL of phenol addition, 7.00mL of sulfuric acid addition, and 15.00min of color development time.

3.5.1 Verification of the best optimization conditions

The electroplating solution was prepared by the "3.1" sample pretreatment method, and the color reaction was carried out when the addition of phenol was 0.80mL, the addition of sulfuric acid was 7.00mL, and the color development time was 15.00min, and the absorbance was measured at a wavelength of 490nm by a UV spectrophotometer, and the parallel measurement Three times, the glucose content and RSD were calculated.

Glucose content is calculated according to formula (3):

In the formula:

m——sample pipetting volume, mL; 1000——conversion factor;

C _A - mass concentration of glucose in the sample, μg/mL;

V——sample constant volume, mL;

It can be seen from the measurement results that under this condition, the average glucose content in the electroplating solution is 3.0771 mg/mL, which is close to the predicted value of 3.1028 mg/mL, indicating that the method is feasible. The three-time RSD is 0.02%, less than 1.5%, and the accuracy and precision are good.

4. Methodological investigation of experimental results

4.1 Experimental results of instrument precision

Accurately take 2mL of the sample solution in "3.1.3" into a 25mL stoppered colorimetric tube, develop color according to the experimental method in "3.3", use distilled water as a reference, and use UV-Vis at the absorption wavelength of 490nm The absorbance was continuously measured 6 times by a spectrophotometer, and the RSD value was calculated. The absorbance of the electroplating solution was continuously measured 6 times, and the measurement results are shown in Table 3-4. It can be seen from Table 3-4 that after measuring the absorbance of glucose in the electroplating solution 6 times continuously, the average content of glucose in the electroplating solution is 3.15 mg/mL, and the RSD is 0.01%, which is less than 1.5%, indicating that the precision of this method is better.

Table 3-4 Precision experiment results

4.2 Repeatability experiment results

In the repeatability experiment, the absorbance of the 6 groups of electroplating solutions was measured, and each group was measured 3 times in parallel. The test results are shown in Table 3-5. It can be seen from Table 3-5 that the average content of glucose in the electroplating solution is 3.13 mg/mL, and the RSD is 0.04%, which is less than 1.5%, indicating that the method has good repeatability.

Table 3-5 Repeatability experiment results

4.3 Experimental results of standard recovery and method precision

For the recovery rate experiment of standard addition, glucose standard solution with a concentration of 15 μg/mL was added to the electroplating solution, and the sample was measured in parallel three times at an absorption wavelength of 490 nm. The results obtained are shown in Table 3-6.

Table 3-6 Experimental results of standard addition recovery (n=3)

The results in Table 3-6 show that the recovery rate of glucose in the electroplating solution is 100.12%, the RSD is 0.76%, which is lower than 1.5%, and the method has good precision.

The recovery rate of standard addition is calculated according to formula (4):

In the formula:

P——recovery rate of standard addition, %;

C1—sample concentration before standard addition, mg/mL;

C2—sample concentration after standard addition, mg/mL;

C3——scaling amount, μg/mL.

The present invention takes lithium battery copper foil electroplating solution as the research object, uses phenol-sulfuric acid method as the color development method, establishes and optimizes the determination method of glucose content in the electroplating solution. Through the single factor experiment, according to the experimental results, the amount of phenol added, the amount of sulfuric acid added and the color development time were selected as independent variables to carry out the "Box-Behnken" design analysis experiment with 3 factors and 3 levels, and the experimental conditions were further optimized by the response surface method. Draw the following conclusions:

(1) The content of copper ions in the electroplating solution was measured by atomic absorption spectrophotometer to be 113.10 mg/L, and nickel, iron and zinc ions were not detected. The method of masking with thiourea and adding activated carbon was not effective, so copper extractant ZJ988 was selected for removal. When the pH of the electroplating solution is 3.5 and the ratio of water phase: oil phase is 1:2, 30% ZJ988 extractant is used for extraction, the extraction time is 5 min, and the water phase is taken after standing for 10 min for measurement. The measurement results show that the average extraction rate of copper ions can reach 96.91%, and high-purity copper can be extracted effectively, and the interference of Cu2+ on the determination of glucose can be eliminated.

(2) Through the analysis of single factor experiment and response surface method, the experimental conditions for the determination of glucose content in the best electroplating solution are as follows: the addition of phenol is 0.84mL, the addition of sulfuric acid is 6.71mL, and the color development time is 15.50min. The glucose content in it is 3.1028mg/mL. In consideration of the actual operation, the actual method parameters were adjusted to be 0.80 mL of phenol, 7.00 mL of sulfuric acid, and 15.00 min of color development time.

(3) Under the optimal optimization condition, measure the glucose content in three groups of electroplating solutions, the result shows that the glucose average content in the electroplating solution is 3.0771mg/mL, close to theoretical value 3.1028mg/mL, RSD is 0.02%, is less than 1.5%, illustrates The method is feasible and has good accuracy.

(4) The glucose standard curve of the method built has a good linear relationship in the range of 5.0-30.0 μg/mL, the experimental result of standard addition recovery is 100.12%, and the RSD is 0.76%. The RSD of the instrument precision and repeatability experiments are respectively 0.01%, 0.04%, indicating that the precision of the instrument is high, the accuracy of the method is good, and it can be used to determine the glucose content in the lithium battery copper foil electroplating solution.

Claims (1)

1. a kind of assay method of glucose in lithium electric copper foil electroplating solution is characterized in that, comprises the following steps: A. Sample pretreatment (1) Adjust the pH value of the solution Put the electroplating solution with a volume of 20mL in a 50mL beaker, use 0.1mol/L sodium hydroxide solution and 0.1mol/L sulfuric acid solution as regulators, monitor the pH value of the solution with a pH meter, and stir while adjusting to make it evenly mixed , so that the pH of the solution reaches 3.5; (2) Extraction of copper ions in the electroplating solution Measure 5mL of the adjusting solution in step (1) in a separatory funnel, with the ratio of water phase: oil phase as 1:2, add 10mL of 30% ZJ988 extractant, shake for 5min, let stand for 10min, take the water phase for later use; (3) Preparation of sample solution Measure 0.5mL of the extract extracted in step (2) into a 100mL volumetric flask, add deionized water to dilute to the mark, mix well and set aside; B. Determination of copper, nickel, iron and zinc Turn on the main engine of the atomic absorption spectrophotometer and the hollow cathode lamp detector to preheat for 15 minutes. At the same time, set the element detection parameters, turn on the air acetylene, air compressor and exhaust box in turn, and ignite after everything is ready, follow the prompts in order Carry out standard solution calibration curve drawing and measure the absorbance of metal ions in the electroplating solution, then calculate the metal ion content in the electroplating solution according to the linear regression equation of the standard solution, measure in parallel 3 times; C. Determination of glucose Use the phenol-sulfuric acid method to develop the color of the sample solution, measure glucose standard solution 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6mL, put them into 25mL stoppered colorimetric tubes, add water to 2.0mL, and Take 2.0mL of the sample solution, and use distilled water as a reference; add 0.8mL of 6% phenol solution and shake well, immediately add 7mL of concentrated sulfuric acid solution, leave it at room temperature for 5min, and then put it in a hot water bath with a temperature of 50℃. After coloring for 15 minutes, put it in a cold water bath for 45 minutes, and cool it down to room temperature; measure the absorbance under a UV-Vis spectrophotometer with a wavelength of 490 nm, draw a regression equation and calculate the glucose content in the sample. D. Calculation formula Metal ion content is calculated according to formula (1):

In the formula: X - the content of the analyte in mg/mL; Cx—mass concentration of any metal ion in the sample, mg/L; D—sample dilution factor; The extraction rate is calculated according to formula (2):

In the formula: R——extraction rate, %; C ₀ , Ce—concentration of the ion to be measured in the solution before and after extraction, mg/L; Glucose content is calculated according to formula (3):

In the formula: m——sample pipetting volume, mL; 1000——conversion factor; C _A - mass concentration of glucose in the sample, μg/mL; V——sample constant volume, mL; The recovery rate of standard addition is calculated according to formula (4):

In the formula: P——recovery rate of standard addition, %; C1—sample concentration before standard addition, mg/mL; C2—sample concentration after standard addition, mg/mL; C3——scaling amount, μg/mL.

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