Method for distinguishing copper ions and barium ions

Abstract

The invention relates to a method for distinguishing copper ions and barium ions, which is characterized in that a 'Formaldehyde-Na2S2O5-Na2SO3-EDTA-D-gluconic acid-delta-lactone' pH clock reaction system is used as a distinguishing solution, and qualitative analysis on the copper ions and the barium ions is realized according to different influences of the copper ions and the barium ions on the highest pH value of the clock system and the time for reaching the highest pH value. The qualitative analysis method for the copper ions and the barium ions has the characteristics of high accuracy, easiness in operation, convenience, rapidness and the like.

Description

Technical Field

[0001] The present invention relates to a discrimination method. Specifically, a pH clock system of "formaldehyde - Na2S2O5 - Na2SO3 - EDTA - D - glucono - δ - lactone" is established, and according to the different effects of the sample to be discriminated on the highest pH value of the clock system and the time to reach the highest pH value, the discrimination of the sample to be discriminated is realized, belonging to the field of analytical chemistry. Background Art

[0002] Metal ions widely exist in nature and play a huge role in human life. Cupric ions can be used for sterilization. The principle of cupric ion sterilization is an effective method to inhibit the growth of microorganisms and has been widely applied in fields such as water treatment, medical equipment, and food processing. By reasonably controlling the concentration and contact time of cupric ions, the killing and growth blocking of bacteria, fungi, and viruses can be achieved. The cupric ion sterilization method has advantages such as simplicity and environmental protection. Generally speaking, the application of the principle of cupric ion sterilization is of great significance for improving the living environment and ensuring public health.

[0003] The ion of barium has a +2 charge and often exists in the form of a divalent cation (Ba 2+ ) in compounds. Compounds of barium are widely used in many applications in the chemical industry, such as the preparation of glass, ceramics, and steel. In the medical field, barium agents are widely used in gastrointestinal X - ray contrast examinations. It should be noted that high - concentration barium salts are toxic to the human body, so its content must be strictly controlled during the drinking water treatment process. To sum up, different metal ions have different functions in nature and the human body. In order to better utilize these metal ions, it is very necessary to distinguish these metal ions.

[0004] At present, common ways to distinguish metal ions include ultraviolet - visible spectrophotometry (UV), fluorescence probe technology (FP), atomic absorption spectrometry (AAS), atomic emission spectrometry (AES), and inductively coupled plasma mass spectrometry (ICP - MS), etc. Although these analytical methods have their own advantages in metal ion detection, they all require expensive and sophisticated test instruments, and the later maintenance cost of the instruments is also very high, which is not suitable for on - site testing. Therefore, it is very necessary to find a detection and analysis method with good detection effect and simple and rapid operation. Summary of the Invention

[0005] The present invention aims to provide a novel, convenient and rapid method for differentiating copper ions and barium ions, that is, a method for qualitatively detecting a sample solution to be differentiated by using a "formaldehyde - Na2S2O5 - Na2SO3 - EDTA - D - glucono - δ - lactone" pH clock system as a differentiating solution. This method is based on the different sensitive responses of this pH clock system to different metal ions. Specifically, the "formaldehyde - Na2S2O5 - Na2SO3 - EDTA - D - glucono - δ - lactone" pH clock reaction system is used as a differentiating solution, and the graph of pH changing with time is recorded; when the pH clock reaction starts, equal - volume and same - concentration sample solutions containing copper ions and barium ions to be differentiated are respectively added to two groups of pH clock systems. According to the different effects of the sample solution to be differentiated on the highest pH value of the clock system and the time to reach the highest pH value, the qualitative differentiation of the sample solution to be differentiated is realized.

[0006] The difference between this qualitative differentiation method and the prior art is that the present invention uses a "formaldehyde - Na2S2O5 - Na2SO3 - EDTA - D - glucono - δ - lactone" pH clock system as a differentiating solution, and realizes the differentiation of the sample solution to be differentiated according to the different effects of the sample solution to be differentiated on the highest pH value of the clock system and the time to reach the highest pH value: compared with the graph of the pH value changing with time of the pH clock system without adding the sample solution to be differentiated, if after adding the sample solution to be differentiated, the highest pH value of the clock system drops significantly and the time to reach the highest pH value is extended to a large extent, then the sample solution added is a copper - ion sample; if after adding the sample solution to be differentiated, the highest pH value of the clock system drops slightly and the time to reach the highest pH value is extended to a small extent, then the sample solution added is a barium - ion sample. When the sample solution to be differentiated is detected in the differentiating solution (pH clock system), the temperature of the pH clock system is controlled within any specific temperature in the range of 25 - 35 °C.

[0007] The distinguishable concentration range of copper ions and barium ions in the differentiating solution (pH clock system) is 2.5×10 -3 -7.5×10 -3 mol / L.

[0008] The distinguishable concentration range of the above - mentioned sample solution to be differentiated is the optimal concentration range determined through experiments. Within this concentration range, the differences in the effects of copper ions and barium ions on this differentiating solution are very obvious, easy to observe and analyze, and easy to achieve differentiation. In addition, the concentration ranges of each component in the differentiating solution (pH clock system) are shown in Table 1, and the best solution of the differentiating solution (pH clock system) obtained through multiple experiments is shown in Table 2: Table 1: Concentrations of each component in the pH clock system

[0009] Table 2: Optimal Concentrations of Each Component in the pH Clock System

[0010] The specific experimental steps are as follows: 1. Prepare 40 mL of the discrimination solution (pH clock system) within the concentration range specified in Table 1, and control its temperature at a specific constant value between 25 - 35 °C. Insert the prepared working electrode (pH combination electrode, Leici, E-331) into the solution. Connect the other end of the working electrode to a computer through a potential / temperature / pH comprehensive tester (Jiaxing Disheng Electronic Technology Co., Ltd., ZHFX-595). After setting the acquisition time and sampling speed in the chemical signal acquisition and analysis program on the computer, quickly click the start button to monitor the pH of the solution. The computer records the curve of the pH of the clock system changing with time, that is, the pH clock map. When detecting a substance, quickly add the substance to be detected simultaneously when the pH clock system reaction starts, and record the pH clock map of the pH changing with time in the same way.

[0011] The basic parameters of the pH clock map include: The time when the clock system reaches the highest pH value: The time required from the start of the pH clock system reaction until the pH of the clock system reaches the highest value. Brief Description of the Drawings

[0012] Figure 1 It is the map of the pH value of the discrimination solution (pH clock system) changing with time in Example 1 when no sample to be discriminated is added.

[0013] Figure 2 It is the map of the pH value of the discrimination solution (pH clock system) changing with time in Example 1 after adding 2.5×10 -3 mol / L copper ions.

[0014] Figure 3 It is the map of the pH value of the discrimination solution (pH clock system) changing with time in Example 1 after adding 2.5×10 -3 mol / L barium ions.

[0015] Figure 4 It is the map of the pH value of the discrimination solution (pH clock system) changing with time in Example 2 when no sample to be discriminated is added.

[0016] Figure 5 It is the map of the pH value of the discrimination solution (pH clock system) changing with time in Example 2 after adding 5×10 -3 mol / L copper ions.

[0017] Figure 6In Example 2, after adding 5×10 -3 mol / L barium ions, it is the graph showing the change of the pH value of the discrimination solution (pH clock system) over time.

[0018] Figure 7 In Example 3, when no sample to be discriminated is added, it is the graph showing the change of the pH value of the discrimination solution (pH clock system) over time.

[0019] Figure 8 In Example 3, after adding 7.5×10 -3 mol / L copper ions, it is the graph showing the change of the pH value of the discrimination solution (pH clock system) over time.

[0020] Figure 9 In Example 3, after adding 7.5×10 -3 mol / L barium ions, it is the graph showing the change of the pH value of the discrimination solution (pH clock system) over time. Detailed implementation method Example 1

[0021] In this example, the feasibility of the method for discriminating copper ions and barium ions of the present invention is verified according to the following steps: (1) Prepare the discrimination solution First, prepare 0.5 mol / L formaldehyde solution, 0.125 mol / L Na2S2O5 solution, 0.05 mol / L Na2SO3 solution, 0.005 mol / L EDTA solution, and 0.04 mol / L D-glucono-δ-lactone solution with distilled water respectively. Add 15 mL of the mixed solution of 0.125 mol / L Na2S2O5, 0.05 mol / L Na2SO3 and 0.005 mol / L EDTA, 15 mL of 0.04 mol / L D-glucono-δ-lactone solution, and 10 mL of 0.5 mol / L formaldehyde solution into a 50 mL small beaker in sequence to ensure that the concentrations of each component in the "formaldehyde - Na2S2O5 - Na2SO3 - EDTA - D-glucono-δ-lactone" pH clock system are formaldehyde 1.25×10 -1 mol / L, Na2S2O5 4.69×10 -2 mol / L, Na2SO3 1.88×10 -2 mol / L, EDTA 1.88×10 -3 mol / L, D-glucono-δ-lactone 1.5×10 -2 mol / L, and the total volume is 40 mL, and the temperature is controlled at 27°C.

[0022] Meanwhile, using distilled water as the solvent, a series of sample solutions containing copper ions and barium ions with different concentrations were prepared for differentiation.

[0023] (2) Obtain the pH clock graph The graph of the change in the pH value of the prepared differentiation solution (pH clock system) over time was recorded by a computer equipped with a chemical signal acquisition and analysis program (without adding the sample to be detected). As Figure 1 shown, the time for the clock system to reach the highest pH value was 87 s, and the highest pH value was approximately 9.7 for the blank control. Another two groups of differentiation solutions with the same component concentrations as the above-mentioned differentiation solution were prepared. For one group, at the same time as the reaction started, 200 μL of 0.5 mol / L copper ion sample solution was added to 40 mL of the pH clock system, so that its concentration in the differentiation solution was 2.5×10 -3 mol / L. The added copper ions extended the time for the clock system to reach the highest pH value to 115 s, and the highest pH value was approximately 9.1, as Figure 2 shown; for the other group, at the same time as the reaction started, 200 μL of 0.5 mol / L barium ion sample solution was added to 40 mL of the pH clock system, so that the concentration of barium ions in the differentiation solution was 2.5×10 -3 mol / L. The added barium ions changed the time for the clock system to reach the highest pH value to 100 s, and the highest pH value was approximately 9.6, as Figure 3 shown.

[0024] (3) Differentiation Since copper ions and barium ions have different structures, their effects on the highest pH value of the clock system and the time to reach the highest pH value are also different. By comparing Figure 1 , Figure 2 , Figure 3 it can be seen that compared with the graph of the change in the pH value over time of the pH clock system without adding the solution to be differentiated, the addition of copper ions causes a larger decrease in the highest pH value of the clock system and a greater extension of the time to reach the highest pH value; the addition of barium ions causes a smaller decrease in the highest pH value of the clock system and a smaller extension of the time to reach the highest pH value. From the above experiments, it can be concluded that by comparing the highest pH value of the clock system and the time to reach the highest pH value, copper ions and barium ions can be differentiated.

[0025] Take two pre-prepared 0.5 mol / L solutions of the samples to be distinguished (one is a copper ion solution and the other is a barium ion solution, but they have not been distinguished yet). Mark one of them as sample 1 and the other as sample 2; prepare two sets of distinguishing solutions with the same component concentrations as above, and add 200 μL of 0.5 mol / L sample 1 and sample 2 respectively, so that their concentrations in the distinguishing solution are 2.5×10 -3 mol / L.

[0026] Analysis and comparison show that: the addition of sample 1 causes a relatively large decrease in the highest pH value of the clock system and a relatively large extension of the time to reach the highest pH value (the highest pH value and the time to reach the highest pH value correspond to Figure 2 and do not correspond to Figure 3 ), while the addition of sample 2 causes a relatively small decrease in the highest pH value of the clock system and a relatively small extension of the time to reach the highest pH value ((the highest pH value and the time to reach the highest pH value correspond to Figure 3 and do not correspond to Figure 2 ). Therefore, sample 1 is a copper ion solution and sample 2 is a barium ion solution, thus realizing the distinction between copper ions and barium ions. Example 2

[0027] This example verifies the feasibility of the method for distinguishing copper ions and barium ions of the present invention according to the following steps: (1) Prepare the distinguishing solution First, prepare 0.5 mol / L formaldehyde solution, 0.125 mol / L Na2S2O5 solution, 0.05 mol / L Na2SO3 solution, 0.005 mol / L EDTA solution, and 0.04 mol / L D-glucono-δ-lactone solution with distilled water respectively. Add 15.2 mL of 0.125 mol / L Na2S2O5, 0.05 mol / L Na2SO3, and 0.005 mol / L EDTA mixed solution, 14.9 mL of 0.04 mol / L D-glucono-δ-lactone solution, and 9.9 mL of 0.5 mol / L formaldehyde solution to a 50 mL small beaker in sequence to ensure that the concentrations of each component in the "formaldehyde - Na2S2O5 - Na2SO3 - EDTA - D-glucono-δ-lactone" pH clock system are formaldehyde 1.24×10 -1 mol / L, Na2S2O5 4.75×10 -2 mol / L, Na2SO3 1.9×10 -2 mol / L, EDTA 1.9×10 -3 mol / L, D-glucono-δ-lactone 1.49×10 -2 mol / L, with a total volume of 40 mL, and the temperature is controlled at 27 °C.

[0028] Meanwhile, using distilled water as the solvent, a series of sample solutions to be distinguished containing copper ions and barium ions with different concentrations were prepared respectively.

[0029] (2)Obtain the pH clock diagram The diagram of the change in the pH value of the prepared distinguishing solution (pH clock system) over time was recorded by a computer equipped with a chemical signal acquisition and analysis program (without adding the sample to be detected). As Figure 4 shown. The time for the clock system to reach the highest pH value is 88 s, and the highest pH value is approximately 9.7 for the blank control. Another two groups of distinguishing solutions with the same component concentrations as the above-mentioned distinguishing solution were prepared. For one group, simultaneously at the start of the reaction, 200 μL of 1 mol / L copper ion sample solution was added to 40 mL of the pH clock system, so that its concentration in the distinguishing solution is 5×10 -3 mol / L. The added copper ions extended the time for the clock system to reach the highest pH value to 150 s, and the highest pH value is approximately 8.4, as Figure 5 shown; for the other group, simultaneously at the start of the reaction, 200 μL of 1 mol / L barium ion sample solution was added to 40 mL of the pH clock system, so that the concentration of barium ions in the distinguishing solution is 5×10 -3 mol / L. The added barium ions changed the time for the clock system to reach the highest pH value to 116 s, and the highest pH value is approximately 9.2, as Figure 6 shown.

[0030] (3) Distinguish Since copper ions and barium ions have different structures, their effects on the highest pH value of the clock system and the time to reach the highest pH value are also different. By comparing Figure 4 、 Figure 5 、 Figure 6 it can be seen that the addition of copper ions causes a relatively large decrease in the highest pH value of the clock system and a relatively large extension of the time to reach the highest pH value; the addition of barium ions causes a relatively small decrease in the highest pH value of the clock system and a relatively small extension of the time to reach the highest pH value. From the above experiments, it can be known that by comparing the highest pH value of the clock system and the time to reach the highest pH value, copper ions and barium ions can be distinguished.

[0031] Take two pre-prepared 1 mol / L solutions of the samples to be distinguished (one is a copper ion solution and the other is a barium ion solution, but they have not been distinguished yet), mark one as sample 1 and the other as sample 2; prepare two sets of distinguishing solutions with the same component concentrations as above, and add 200 μL of 1 mol / L sample 1 and sample 2 respectively, so that their concentrations in the distinguishing solution are 5×10 -3 mol / L.

[0032] Analysis and comparison show that: the addition of sample 1 causes a relatively large decrease in the highest pH value of the clock system and a relatively large extension of the time to reach the highest pH value (the highest pH value and the time to reach the highest pH value correspond to Figure 5 and do not correspond to Figure 6 ), while the addition of sample 2 causes a relatively small decrease in the highest pH value of the clock system and a relatively small extension of the time to reach the highest pH value ((the highest pH value and the time to reach the highest pH value correspond to Figure 6 and do not correspond to Figure 5 ). Therefore, sample 1 is a copper ion solution and sample 2 is a barium ion solution, thus realizing the distinction between copper ions and barium ions. Example 3

[0033] This example verifies the feasibility of the method for distinguishing copper ions and barium ions of the present invention according to the following steps: (1) Prepare the distinguishing solution First, prepare 0.5 mol / L formaldehyde solution, 0.125 mol / L Na2S2O5 solution, 0.05 mol / L Na2SO3 solution, 0.005 mol / L EDTA solution, and 0.04 mol / L D-glucono-δ-lactone solution with distilled water respectively. Add 14.7 mL of the mixed solution of 0.125 mol / L Na2S2O5, 0.05 mol / L Na2SO3 and 0.005 mol / L EDTA, 15.2 mL of 0.04 mol / L D-glucono-δ-lactone solution, and 10.1 mL of 0.5 mol / L formaldehyde solution to a 50 mL small beaker in sequence to ensure that the concentrations of each component in the "formaldehyde - Na2S2O5 - Na2SO3 - EDTA - D-glucono-δ-lactone" pH clock system are formaldehyde 1.26×10 -1 mol / L, Na2S2O5 4.59×10 -2 mol / L, Na2SO3 1.84×10 -2 mol / L, EDTA 1.84×10 -3 mol / L, D-glucono-δ-lactone 1.52×10 -2 mol / L, with a total volume of 40 mL, and the temperature was controlled at 27 °C.

[0034] Meanwhile, using distilled water as the solvent, series of sample solutions of copper ions and barium ions with different concentrations were prepared for differentiation.

[0035] (2) Obtaining the pH clock graph The graph of the change in pH value of the prepared differentiation solution (pH clock system) over time was recorded by a computer equipped with a chemical signal acquisition and analysis program (without adding the sample to be detected). As Figure 7 shown. The time for the clock system to reach the highest pH value was 87 s, and the highest pH value was approximately 9.7 for blank control. Another two groups of differentiation solutions with the same component concentrations as the above-mentioned differentiation solution were prepared. For one group, simultaneously at the start of the reaction, 200 μL of 1.5 mol / L copper ion sample solution was added to 40 mL of the pH clock system, such that its concentration in the differentiation solution was 7.5×10 -3 mol / L. The addition of copper ions extended the time for the clock system to reach the highest pH value to 179 s, and the highest pH value was approximately 7.5, as Figure 8 shown; for the other group, simultaneously at the start of the reaction, 200 μL of 1.5 mol / L barium ion sample solution was added to 40 mL of the pH clock system, such that the concentration of barium ions in the differentiation solution was 7.5×10 -3 mol / L. The addition of barium ions changed the time for the clock system to reach the highest pH value to 132 s, and the highest pH value was approximately 9.0, as Figure 9 shown.

[0036] (3) Differentiation Since copper ions and barium ions have different structures, their effects on the highest pH value of the clock system and the time to reach the highest pH value are also different. By comparing Figure 7 , Figure 8 , Figure 9 it can be seen that the addition of copper ions causes a larger decrease in the highest pH value of the clock system and a greater extension of the time to reach the highest pH value; the addition of barium ions causes a smaller decrease in the highest pH value of the clock system and a smaller extension of the time to reach the highest pH value. From the above experiments, it can be known that by comparing the highest pH value of the clock system and the time to reach the highest pH value, copper ions and barium ions can be differentiated.

[0037] Take two pre-prepared solutions of the samples to be distinguished at a concentration of 1.5 mol / L (one is a copper ion solution and the other is a barium ion solution, but they have not been distinguished yet). Mark one of them as Sample 1 and the other as Sample 2; prepare two sets of distinguishing solutions with the same component concentrations as the above concentrations, and add 200 μL of 1.5 mol / L Sample 1 and Sample 2 respectively, so that their concentrations in the distinguishing solutions are 7.5×10 -3 mol / L.

[0038] Analysis and comparison show that: the addition of Sample 1 causes a relatively large decrease in the highest pH value of the clock system and a significant extension in the time to reach the highest pH value (the highest pH value and the time to reach the highest pH value correspond to Figure 8 and do not correspond to Figure 9 ), while the addition of Sample 2 causes a relatively small decrease in the highest pH value of the clock system and a relatively small extension in the time to reach the highest pH value (the highest pH value and the time to reach the highest pH value correspond to Figure 9 and do not correspond to Figure 8 ). Therefore, Sample 8 is a copper ion solution and Sample 9 is a barium ion solution, thus realizing the distinction between copper ions and barium ions.

[0039] As can be seen from the above examples, copper ions and barium ions in the concentration range of 2.5×10 -3 -7.5×10 -3 mol / L can be distinguished by the method of the present invention.

Claims

1. A method for differentiating copper ions and barium ions, characterized in that: Using distilled water as a solvent, prepare a sample solution of copper ions and barium ions to be differentiated; Apply the "formaldehyde - Na2S2O5 - Na2SO3 - EDTA - D - glucono - δ - lactone" pH clock reaction system as the differentiating solution, and record the graph of the change of the pH value of the clock system over time; The temperature of the pH clock system is controlled at any specific temperature within the range of 25 - 35 °C; when the pH clock reaction starts, add equal - volume and same - concentration sample solutions of copper ions and barium ions to be differentiated into two groups of pH clock systems respectively. According to the different effects of the samples to be differentiated on the highest pH value of the clock system and the time to reach the highest pH value, the differentiation of the samples to be differentiated is realized: compared with the graph of the change of the pH value over time of the pH clock system without adding the sample to be differentiated, if after adding the sample to be differentiated, the highest pH value of the clock system drops significantly and the time to reach the highest pH value is extended to a large extent, then the sample to be differentiated added is a copper - ion sample; if after adding the sample to be differentiated, the highest pH value of the clock system drops slightly and the time to reach the highest pH value is extended to a small extent, then the sample to be differentiated added is a barium - ion sample; The molar concentration ranges for the components in the solution are as follows: formaldehyde 1.21×10 -1 -1.28×10 -1 mol / L, Na2S2O5 4.65×10 -2 -5.50×10 -2 mol / L, Na2SO3 1.65×10 -2 -1.96×10 -2 mol / L, EDTA 1.71×10 -3 -1.95×10 -3 mol / L, D-glucono-δ-lactone 9.88×10 -3 -1.75×10 -2 mol / L.

2. The method according to claim 1, wherein: The molar concentrations of the components in the solution are formaldehyde 1.25×10 -1 mol / L, Na2S2O5 4.69×10 -2 mol / L, Na2SO3 1.88×10 -2 mol / L, EDTA 1.88×10 -3 mol / L, D-glucono-δ-lactone 1.5×10 -2 mol / L.

3. The method according to claim 1, characterized in that: The distinguishable concentration range of the sample to be distinguished in the distinguishing solution is 2.5×10 -3 -7.5×10 -3 mol / L.

4. The method according to claim 1, wherein: The temperature of the clock system is controlled at 27 °C.

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