Method for enhancing heavy metal ion concentration analysis and detection sensitivity and application

Abstract

The invention provides a method for enhancing heavy metal ion concentration analysis and detection sensitivity and application. The method comprises the following steps: S1, carrying out gradient dilution on a heavy metal solution and a zinc ion solution to obtain a dilute solution with a series of concentration gradients; s2, measuring the absorption values of the dilute solutions with the series of concentration gradients by adopting a spectrophotometric method, and establishing a standard curve; according to the method, the zinc ions are introduced as interference variables when the standard curve for measuring the heavy metal ions is constructed, the slope of the standard curve can be remarkably increased by adding the zinc ions, the analysis and detection sensitivity of the spectrophotometric method can be effectively improved, and a new sensitivity optimization strategy is provided for heavy metal ion detection.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical analysis and detection, and in particular to a method and application for enhancing the sensitivity of heavy metal ion concentration analysis and detection. Background Art

[0002] With the rapid development of industry, heavy metal ions are becoming increasingly widespread in the environment. Industrial processes such as mining, metallurgy, chemical engineering, electroplating, and electronics manufacturing are among the main sources of heavy metal ions. In the mining and metallurgical industries, large quantities of heavy metals such as lead, cadmium, mercury, and chromium are extracted from ores. This extraction results in wastewater and waste residues containing high concentrations of heavy metal ions, which are discharged directly into the environment without proper treatment, causing water, soil, and air pollution. The chemical industry also uses and releases heavy metal ions during the production of various chemical products. Furthermore, the irrational use of pesticides and fertilizers in agriculture, as well as the discharge of livestock and poultry wastewater, can lead to the accumulation of heavy metal ions in soil and water. Municipal sewage, waste incineration, and transportation processes also generate certain amounts of heavy metal ions, further exacerbating the problem of heavy metal pollution in the environment. Heavy metal ions are highly toxic, difficult to degrade in the environment, and easily accumulate, posing a serious threat to the ecological environment and human health.

[0003] In order to timely understand the pollution status of heavy metal ions in the environment and protect the ecological environment and human health, it is of great significance to accurately, quickly and sensitively detect heavy metal ions. As an analytical method based on the selective absorption of light by substances, spectrophotometry is widely used in environmental monitoring, biomedicine, food testing, chemical analysis and other fields due to its advantages such as simple operation, low cost and wide application range. In the practical application of spectrophotometry, the construction of the standard curve is the core link of quantitative analysis. Its accuracy and sensitivity directly determine the reliability of the detection results. The slope of the standard curve is one of the key factors determining the detection sensitivity. The slope of the standard curve reflects the responsiveness of the detection signal to changes in concentration. The larger the slope, the more significant the change in the detection signal caused by a unit concentration change, and the higher the detection sensitivity. In traditional methods for detecting heavy metal ions, factors such as light source stability, cuvette cleanliness, and solution color development time may affect the absorption value measurement accuracy, which in turn leads to a small slope of the standard curve, limiting the improvement of detection sensitivity. Summary of the Invention

[0004] In view of this, the present invention proposes a method and application for enhancing the sensitivity of heavy metal ion concentration analysis and detection. The method of the present invention can effectively improve the analytical detection sensitivity of spectrophotometry and provide a new sensitivity optimization strategy for heavy metal ion detection.

[0005] The technical solution of the present invention is achieved as follows:

[0006] A method for enhancing the sensitivity of heavy metal ion concentration analysis and detection, comprising the following steps:

[0007] S1, gradient dilution of the heavy metal solution and the zinc ion solution to obtain a series of dilute solutions with concentration gradients;

[0008] S2. Use spectrophotometry to determine the absorbance of a series of dilute solutions with a concentration gradient and establish a standard curve.

[0009] Furthermore, the concentration of the heavy metal solution is 5 to 30 mg / L; the concentration of the zinc ion solution is 50 to 300 mg / L.

[0010] Furthermore, the concentration of the heavy metal solution is 20 mg / L; the concentration of the zinc ion solution is 0.036 mol / L.

[0011] Furthermore, the spectrophotometry method uses a UV-6300 ultraviolet-visible spectrophotometer to test the absorption value.

[0012] Furthermore, the heavy metal solution is potassium dichromate solution.

[0013] Furthermore, the zinc ion solution is a zinc acetate solution.

[0014] Furthermore, the absorption value is the absorption value at a wavelength of 350 to 370 nm.

[0015] Furthermore, the preparation method of the potassium dichromate solution is: accurately weigh potassium dichromate and place it in a beaker, add deionized water and stir and dissolve it to obtain a solution, transfer the solution to a volumetric flask, rinse the beaker multiple times and transfer the rinse solution to the volumetric flask, and then quantify it with deionized water to the scale line to obtain the potassium dichromate solution.

[0016] Furthermore, the preparation method of the potassium dichromate solution is specifically as follows: accurately weigh 40 mg of potassium dichromate and place it in a 500 mL beaker and add 300 mL of deionized water and stir and dissolve thoroughly to obtain a solution, transfer the solution to a 2 L volumetric flask, rinse the beaker several times and transfer the rinse solution to the volumetric flask, and then quantify with deionized water to the scale line to obtain a potassium dichromate solution.

[0017] Furthermore, the concentrations of the heavy metal solutions in the dilute solutions with concentration gradients after dilution were 17.46 mg / L, 14.55 mg / L, 11.64 mg / L, 8.73 mg / L, 5.82 mg / L and 1.46 mg / L, respectively, and the concentration of zinc ions in the solutions was 214 mg / L.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention introduces zinc ions as an interfering variable when constructing a standard curve for the determination of heavy metal ions. The addition of zinc ions can significantly increase the slope of the standard curve, effectively improve the analytical detection sensitivity of the spectrophotometric method, and provide a new sensitivity optimization strategy for heavy metal ion detection.

[0020] In the preparation of a standard curve of a low-concentration potassium dichromate solution, the invention can significantly improve the detection sensitivity of an ultraviolet-visible spectrophotometer for a low-concentration K2Cr2O7 solution by adding a zinc acetate solution, thereby achieving a good detection effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a graph showing the absorption values ​​of K2Cr2O7 solutions with different concentrations in Example 1 within the wavelength range of 200-600nm.

[0022] Figure 2 This is a curve diagram showing the relationship between the concentration and absorption value of K2Cr2O7 solutions with different concentrations at a wavelength of 350nm in Example 1.

[0023] Figure 3 This is a graph showing the relationship between wavelength and absorption value of K2Cr2O7 solutions with different concentrations in the wavelength range of 200-600 nm when the zinc ion concentration in the dilute solution system of Example 2 is 214 mg / L.

[0024] Figure 4 This is a graph showing the relationship between the concentration and absorption value of K2Cr2O7 solutions of different concentrations under the conditions of a zinc ion concentration of 214 mg / L and a wavelength of 370 nm in the dilute solution system of Example 2.

[0025] Figure 5 This is a graph showing the relationship between the mixed solutions containing different zinc ion concentrations and the absorption value when the K2Cr2O7 solution concentration is 20 mg / L and the wavelength is 370 nm in Example 3.

[0026] Figure 6 This is a graph showing the relationship between wavelength and absorption value of a mixed solution containing K2Cr2O7 at a concentration of 20 mg / L when no zinc ions are added and when a zinc ion concentration of 120 mg / L is added in Example 3; wherein, curve A is a graph showing the relationship between wavelength and absorption value measured for a mixed solution containing K2Cr2O7 at a concentration of 20 mg / L when no zinc ions are added, and curve B is a graph showing the relationship between wavelength and absorption value measured for a mixed solution containing K2Cr2O7 at a concentration of 20 mg / L when a zinc ion concentration of 120 mg / L is added. DETAILED DESCRIPTION

[0027] In order to better understand the technical content of the present invention, specific examples are provided below to further illustrate the present invention.

[0028] Unless otherwise specified, the experimental methods used in the examples of the present invention are all conventional methods.

[0029] Unless otherwise specified, the materials, reagents, etc. used in the examples of the present invention can be obtained from commercial sources.

[0030] Example 1

[0031] The establishment of the CA (concentration-absorption value) curve of the standard potassium dichromate solution includes the following steps:

[0032] S1. Accurately weigh 40 mg of potassium dichromate using an analytical balance, place it in a 500 mL beaker, and add 300 mL of deionized water and stir thoroughly to completely dissolve it. Then transfer the potassium dichromate solution to a 2 L volumetric flask, rinse the beaker several times, and carefully transfer the rinse solution to the volumetric flask. Then, quantify it with deionized water to the scale line. During this period, shake the volumetric flask appropriately to evenly disperse the potassium dichromate solution to obtain a potassium dichromate solution with a concentration of 20 mg / L.

[0033] S2. Dilute the potassium dichromate solution with deionized water to 16 mg / L, 8 mg / L, 4 mg / L, 2 mg / L, 1 mg / L, and 0 mg / L, respectively, as potassium dichromate solutions of different concentrations;

[0034] S3. Use UV-6300 UV-visible spectrophotometer to test the absorbance of potassium dichromate solution with different concentrations in the wavelength range of 200-600nm, and then draw the corresponding relationship curve. Figure 1 and Figure 2 shown.

[0035] Depend on Figure 1 It can be found that K2Cr2O7 solutions with different concentrations have obvious and relatively regular characteristic absorption peaks at a wavelength of 350nm. Therefore, the characteristic absorption values ​​of K2Cr2O7 solutions with different concentrations at 350nm are taken to draw the relationship curve between concentration and absorption value (CA curve). Figure 2 As shown, in the range of K2Cr2O7 solution concentration of 0 to 20 mg / L, the concentration of K2Cr2O7 solution and the characteristic absorption value show a good linear correlation (R1 = 0.99996), and the corresponding CA linear slope k1 = 0.01158.

[0036] Example 2

[0037] A method for enhancing the sensitivity of heavy metal ion concentration analysis and detection comprises the following steps:

[0038] S1. Accurately weigh 40 mg of potassium dichromate using an analytical balance, place it in a 500 mL beaker, and add 300 mL of deionized water and stir thoroughly to completely dissolve it. Then transfer the potassium dichromate solution to a 2 L volumetric flask, rinse the beaker several times, and carefully transfer the rinse solution to the volumetric flask. Then, quantify it with deionized water to the scale line. During this period, shake the volumetric flask appropriately to evenly disperse the potassium dichromate solution to obtain a potassium dichromate solution with a concentration of 20 mg / L.

[0039] S2. 24 mL, 20 mL, 16 mL, 12 mL, 8 mL and 2 mL of a 20 mg / L potassium dichromate solution and 2.5 mL of a 0.036 mol / L zinc acetate solution were gradiently diluted with deionized water to form a dilute solution with a volume of 27.5 mL. The concentrations of the potassium dichromate solution in the diluted solutions were 17.46 mg / L, 14.55 mg / L, 11.64 mg / L, 8.73 mg / L, 5.82 mg / L and 1.46 mg / L, respectively, and the concentration of zinc ions was 214 mg / L.

[0040] S3. Dilute 2.5 mL of 0.036 mol / L zinc acetate solution with deionized water to a volume of 27.5 mL as a reference solution (zinc ion concentration is 214 mg / L);

[0041] S4. Use UV-6300 UV-visible spectrophotometer to test the absorbance of different concentrations of dilute solutions and reference solutions in the wavelength range of 200-600nm, and then draw the corresponding relationship curve. The results are as follows: Figure 3 and Figure 4 shown.

[0042] Figure 3 The graph shows the relationship between wavelength and absorption value of K2Cr2O7 solution with different concentrations in the wavelength range of 200-600nm when the zinc ion concentration in the dilute solution system is 214mg / L. Figure 3 It can be found that adding Zn 2+ The absorption curve of K2Cr2O7 solution changes significantly after addition. Compared with the pure K2Cr2O7 solution, the absorption curve peak is more prominent and sharp. It can be seen that zinc ions can significantly improve the linear shape of the absorption curve of K2Cr2O7 solution. Further comparison shows that the addition of Zn 2+ After that, the characteristic peak of K2Cr2O7 solution at a wavelength of 350nm shifted to 370nm, and the intensity of this characteristic peak increased significantly.

[0043] Figure 4 The graph is a graph showing the relationship between the concentration and absorption value of K2Cr2O7 solutions with different concentrations when the zinc ion concentration is 214 mg / L and the wavelength is 370 nm in a dilute solution system. Figure 4 It can be seen that when the concentration of K2Cr2O7 solution is lower than 20 mg / L, adding Zn 2+ The concentration of K2Cr2O7 solution after addition also showed a good linear correlation with the characteristic absorption value (R2=0.99854), and the corresponding CA linear slope k2=0.02355. The value of k2 is 2.03 times that of k1, indicating that the addition of Zn 2+ After that, the detection sensitivity of UV-visible spectrophotometer for low concentration K2Cr2O7 solution (<20mg / L) was increased to 2.03 times of the original one.

[0044] Example 3

[0045] Different Zn 2+ The determination of the CA (concentration-absorption value) curve of a mixture of a potassium dichromate solution having a concentration of 20 mg / L and a potassium dichromate solution having a concentration of 20 mg / L comprises the following steps:

[0046] S1. Accurately weigh 40 mg of potassium dichromate using an analytical balance, place it in a 500 mL beaker, and add 300 mL of deionized water and stir thoroughly to completely dissolve it. Then transfer the potassium dichromate solution to a 2 L volumetric flask, rinse the beaker several times, and carefully transfer the rinse solution to the volumetric flask. Then, quantify it with deionized water to the scale line. During this period, shake the volumetric flask appropriately to evenly disperse the potassium dichromate solution to obtain a potassium dichromate solution with a concentration of 20 mg / L.

[0047] S2. Dissolve 40 mg of zinc acetate dihydrate in 20 mL, 50 mL, 75 mL, 100 mL, 150 mL, and 200 mL of 20 mg / L potassium dichromate solution, respectively. Ignore the effect of zinc acetate dihydrate on the volume of the solution, and you will get Zn 2+ The concentrations of the test mixtures were 595.7 mg / L, 238.3 mg / L, 158.8 mg / L, 119.1 mg / L, 79.4 mg / L, and 59.6 mg / L, respectively; a 20 mg / L potassium dichromate solution without zinc acetate dihydrate was used as the reference solution;

[0048] S3. Use UV-6300 UV-visible spectrophotometer to test the absorbance of the mixed solution and the reference solution in the wavelength range of 600-200nm, and then draw the corresponding relationship curve. Figure 5 and Figure 6 shown.

[0049] Figure 5 The graph is a relationship between the mixed solution containing different zinc ion concentrations and the absorption value when the concentration of K2Cr2O7 solution is 20 mg / L and the wavelength is 370 nm. Figure 5It can be seen that, in general, as the concentration of zinc ions in the solution increases, the characteristic absorption value of 20 mg / L K2Cr2O7 solution gradually increases. 2+ When the concentration is 120 mg / L, the corresponding characteristic absorption value is 0.413, which is significantly higher than the 0.231 of the simple 20 mg / L K2Cr2O7 solution. 2+ When the concentration is lower than 120 mg / L, as Zn 2+ With the increase of concentration, the corresponding characteristic absorption value increases significantly; when Zn 2+ When the concentration is higher than 120 mg / L, as Zn 2+ With the increase of concentration, the corresponding characteristic absorption value increases slowly, indicating that when 120 mg / L Zn is added to the low concentration K2Cr2O7 solution, the 2+ This is a reasonable and effective method to improve the detection sensitivity of K2Cr2O7 solution by UV-visible spectrophotometer.

[0050] Figure 6 The graph is a relationship between wavelength and absorbance of a mixed solution containing 20 mg / L K2Cr2O7 when no zinc ions are added and when the zinc ion concentration is 120 mg / L. Figure 6 It can be seen that when the mixed solution does not contain zinc ions, the absorption value obtained is significantly lower than that when the mixed solution contains 120 mg / L Zn 2+ The absorption value of curve B of the determination solution shows that by adding zinc ions during the determination, a good complex can be formed with heavy metals, which effectively increases the intensity of the absorption value, thereby improving the detection sensitivity of heavy metal ions.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for enhancing the sensitivity of heavy metal ion concentration analysis and detection, characterized in that: The following steps are involved: S1, gradient dilution of the heavy metal solution and the zinc ion solution to obtain a series of dilute solutions with concentration gradients; S2. Use spectrophotometry to determine the absorbance of a series of dilute solutions with a concentration gradient and establish a standard curve.

2. The method for enhancing the sensitivity of heavy metal ion concentration analysis and detection according to claim 1, characterized in that: The concentration of the heavy metal solution is 5-30 mg / L; the concentration of the zinc ion solution is 50-300 mg / L.

3. The method for enhancing the sensitivity of heavy metal ion concentration analysis and detection according to any one of claims 1 or 2, characterized in that: The concentration of the heavy metal solution is 20 mg / L; the concentration of the zinc ion solution is 214 mg / L.

4. The method for enhancing the sensitivity of heavy metal ion concentration analysis and detection according to claim 1, wherein: The spectrophotometry method uses a UV-6300 ultraviolet-visible spectrophotometer to measure the absorbance value.

5. The method for enhancing the sensitivity of heavy metal ion concentration analysis and detection according to claim 1, wherein: The heavy metal solution is a potassium dichromate solution; and the zinc ion solution is a zinc acetate solution.

6. The method for enhancing the sensitivity of heavy metal ion concentration analysis and detection according to claim 1, wherein: The absorption value is the absorption value at a wavelength of 350 to 370 nm.

7. The method for enhancing the sensitivity of heavy metal ion concentration analysis and detection according to claim 1, wherein: The potassium dichromate solution is prepared by accurately weighing potassium dichromate and placing it in a beaker, adding deionized water and stirring thoroughly to dissolve the solution, transferring the solution to a volumetric flask, washing the beaker several times and transferring the washing solution to the volumetric flask, and then adding deionized water to quantify the amount up to the scale line to obtain the potassium dichromate solution.

8. The method for enhancing the sensitivity of heavy metal ion concentration analysis and detection according to claim 7, characterized in that: The potassium dichromate solution is prepared as follows: 40 mg of potassium dichromate is accurately weighed and placed in a 500 mL beaker, 300 mL of deionized water is added, and the mixture is stirred and dissolved to obtain a solution; the solution is transferred to a 2 L volumetric flask; the beaker is rinsed multiple times and the rinse solution is transferred to the volumetric flask; and then deionized water is added to the scale to obtain the potassium dichromate solution.

9. The method for enhancing the sensitivity of heavy metal ion concentration analysis and detection according to claim 1, wherein: The concentrations of heavy metal solutions in the dilute solutions with concentration gradients after dilution were 17.46 mg / L, 14.55 mg / L, 11.64 mg / L, 8.73 mg / L, 5.82 mg / L and 1.46 mg / L, respectively.

10. The method for enhancing the sensitivity of heavy metal ion concentration analysis and detection according to claim 1, characterized in that: The method is applied in the determination of heavy metal ions by spectrophotometry.

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