A rapid spectrophotometric detection method for ultra-low concentration copper ions

Abstract

This invention discloses a rapid spectrophotometric detection method for ultra-low concentration copper ions, belonging to the detection of divalent copper ions, a heavy metal. The method includes the following steps: (1) adding the colorimetric reagent tetrakis(4-acetoxyphenyl)porphyrin and the surfactant Triton X-100 to the sample to be tested, adjusting the pH of the system to acidic, mixing thoroughly, and allowing the mixture to stand for reaction; (2) after the reaction is complete, measuring the absorbance by spectrophotometry, and mapping the measured absorbance value to the divalent copper ion standard curve to obtain the copper ion concentration of the sample to be tested. This invention provides a rapid spectrophotometric detection method for ultra-low concentration copper ions, employing specific detection methods and conditions, which can effectively detect Cu in water, such as industrial wastewater. 2+ The method for detecting copper content in water is simple, has low instrument cost, and high sensitivity, and can fully meet the existing maximum limit requirements. It is a new method for detecting heavy metal copper in water that is easy to promote and use.

Description

Technical Field

[0001] This invention relates to the detection of divalent copper ions, a heavy metal, and particularly to a rapid spectrophotometric detection method for ultra-low concentration copper ions. Background Technology

[0002] Copper is a metallic element that is widely found in nature. Copper ions (Cu) 2+ Porphyrin (COP) is the primary form of copper, an essential trace element for the life activities of plants, animals, and humans, participating in physiological processes such as enzyme activity regulation and metabolism. It also possesses the characteristics of being non-degradable and bioaccumulating. With the advancement of industrial production and agricultural activities, the environmental emission and pollution of copper ions are becoming increasingly serious, leading to increasingly stringent limits on copper ion concentrations in water and soil, and an urgent need for accurate detection of ultra-low concentrations of copper ions. Traditional copper ion detection methods suffer from drawbacks such as expensive instruments, cumbersome operation, and limitations in on-site detection, and lack sufficient sensitivity for detecting trace amounts of copper ions. Therefore, research on highly sensitive and selective detection of copper ions based on porphyrin materials is of significant research value and practical importance for solving the problem of detecting trace copper ions in the environment and ensuring ecological security and human health.

[0003] Currently, methods for detecting heavy metal copper ions include atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS), inductively coupled plasma atomic emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence spectrometry (XRF), ultraviolet-visible spectrophotometry, flame atomic absorption spectrometry (FAAS), and graphite furnace atomic absorption spectrometry (GFAAS). Each of these methods has its own advantages and applicable scenarios. The appropriate detection technology can be selected according to specific detection needs and conditions. However, some methods involve large-scale instruments, are costly, complex to operate, and difficult to popularize.

[0004] Spectrophotometry has been widely used due to its advantages such as simplicity, speed, high sensitivity, low cost, and ease of promotion.

[0005] The current standard for the spectrophotometric determination of copper ions is the DDTC spectrophotometric method for the determination of copper in water (HJ485-2009), with a limit of detection of 0.01 mg / L. Detection of copper ions at concentrations below 0.01 mg / L remains a challenge. Therefore, developing novel, rapid spectrophotometric methods for the detection of ultra-low concentrations of copper ions is of great significance in addressing this limitation. Summary of the Invention

[0006] Objective of the Invention: To address the aforementioned technical problems, this invention aims to provide a rapid spectrophotometric detection method for ultra-low concentration copper ions. This method employs specific detection techniques and conditions, and the chromogenic reagent used contains substances similar to Cu. 2+The coordination sites are highly sensitive, stable, and easy to operate, making them effective for detecting Cu in water, such as industrial wastewater. 2+ The method for detecting copper in water is simple, has low instrument cost, and high sensitivity, and can fully meet the existing maximum limit requirements. It is a new method for detecting heavy metal copper in water that is easy to promote and use, and has strong innovative significance and practical value.

[0007] Technical Solution: To achieve the above objectives, the present invention provides a rapid spectrophotometric detection method for ultra-low concentration copper ions, comprising the following steps:

[0008] (1) Add colorimetric reagent tetra(4-acetoxyphenyl)porphyrin and surfactant Triton X-100 to the sample to be tested, adjust the pH of the system to acidic, mix well and let it stand to react;

[0009] (2) After the reaction is complete, the absorbance is measured by spectrophotometry. The measured absorbance value is then matched with the standard curve of divalent copper ions to obtain the copper ion concentration of the sample to be tested.

[0010] The chromogenic agent tetra(4-acetoxyphenyl)porphyrin has the following structural formula:

[0011] .

[0012] In step (1), the concentration of the colorimetric reagent is 300-400 mg / L, and the amount added is 0.2-1.0 mL.

[0013] In step (1), the amount of surfactant added is 0.2-1.4 mL, and the concentration is 1-5%.

[0014] Preferably, the surfactant in step (1) is Triton X-100.

[0015] Preferably, the concentration of the colorimetric reagent in step (1) is 400 mg / L and the amount added is 1 mL.

[0016] Preferably, the surfactant is a 4% Triton X-100 solution, added in an amount of 0.8 mL.

[0017] In step (1), hydrochloric acid solution is added to adjust the pH value of the system. The concentration is 0.2-0.3 mol / L, and the pH value is adjusted to 4-6.

[0018] In step (1), the pH is adjusted to 4 to 4.7.

[0019] Furthermore, in step (1), the concentration of hydrochloric acid is 0.3 mol / L, and the pH value of the reaction system is adjusted to around 4.7.

[0020] In step (1), the reaction time after mixing is 5-30 min and the reaction temperature is 10-60℃.

[0021] Preferably, in step (1), the reaction time after mixing is 5-30 min and the reaction temperature is 25-35℃.

[0022] Furthermore, in step (1), the reaction time after mixing is 5 min and the reaction temperature is 25℃.

[0023] Furthermore, the medium for the reaction after mixing and standing in step (1) is N,N-dimethylformamide (DMF).

[0024] In step (2), the absorbance is measured by spectrophotometry, and the maximum absorption wavelength of divalent copper ions is 451 nm.

[0025] The environment in which the detection is performed includes aquatic or soil environments.

[0026] Preferably, the method for preparing the chromogenic agent tetra(4-acetoxyphenyl)porphyrin according to the present invention includes the following steps:

[0027] In a round-bottom flask, 4-hydroxybenzaldehyde, triethylamine, and anhydrous tetrahydrofuran were added sequentially. Under nitrogen protection, the mixture was stirred, and acetyl chloride was slowly added dropwise. After the addition was complete, the reaction mixture was stirred again at room temperature under nitrogen protection. After the reaction was complete, the reaction mixture was filtered, and the solid was washed with tetrahydrofuran until nearly white. The solid was discarded, and the brown filtrate was collected. The filtrate was distilled under reduced pressure to remove the solvent, yielding a brown oil. This oil was dissolved in dichloromethane and washed successively with saturated sodium bicarbonate solution and distilled water. This washing process was repeated 1-2 times. The organic phase was collected and dried over anhydrous magnesium sulfate for later use. The dried oil was then mixed with 4-ethoxybenzaldehyde, and the mixture was dissolved in propionic acid and refluxed. After the reaction was complete, the mixture was cooled to room temperature, and the precipitated solid was filtered off. The solid was washed with methanol until the filtrate was colorless, yielding the target product.

[0028] The application of the spectrophotometric rapid detection method of copper ions in the environment using the colorimetric reagent tetra(4-acetoxyphenyl)porphyrin described in this invention.

[0029] The detection method of the present invention mainly includes the following steps:

[0030] Measurement condition optimization: By finely controlling the pH value, selecting the appropriate type and concentration of acid solution, optimizing the type and amount of surfactant, determining the optimal maximum absorption wavelength, and setting the measurement parameters reasonably, the sensitivity and stability can be maximized.

[0031] Repeatability study: The same sample is tested multiple times to examine the repeatability of the test results under the same conditions, in order to evaluate the stability of the test method and reagents.

[0032] Method reliability assessment: The detection results of this invention are compared with standard solutions to verify its accuracy and precision, and to ensure the reliability of the detection method.

[0033] A standard curve was plotted using spectrophotometry, with the copper concentration of the copper standard solution and the absorbance value of the corresponding standard solution to be tested as the ordinate and the concentration of divalent copper ions as the abscissa.

[0034] Obtain the test solution, pretreat it, and then add acid to adjust the pH value of the test standard solution.

[0035] Add a colorimetric reagent and a surfactant to the test solution, mix, and let stand.

[0036] The Cu-containing sample was analyzed by spectrophotometry. 2+ The detection showed that Cu was detected by ultraviolet absorption. 2+ The measurement wavelength was 451 nm.

[0037] After the reaction is complete, the absorbance is measured by spectrophotometry. The measured absorbance value is then mapped to the standard curve to obtain the copper ion concentration of the sample.

[0038] Cu in the detection method of this invention 2+ The linear equation of the standard curve is y = 0.06749 + 85.12508x, R0 2 =0.99617, the detection range of divalent copper ion concentration is 5~150 ug / L, and the detection limit of divalent copper ion concentration is 0.133 ug / L.

[0039] Preferably, this invention uses a solution with pH 4-6 as the reaction system, tetrakis(4-acetoxyphenyl)porphyrin as the chromogenic agent, Triton X-100 as the surfactant, and employs spectrophotometry to detect divalent copper ions in the aqueous phase. The detection range for divalent copper ions is 5-150 ug / L, and the apparent molar absorptivity is 7.63 × 10⁻⁶. 5 The detection limit is 0.133 ug / L, with a detection limit of L / (mol·cm). It features a low detection limit and high sensitivity, does not cause environmental pollution during the detection process, does not require large instruments, and is simple, efficient, and convenient to operate.

[0040] The colorimetric reagent used in the detection method of this invention contains multiple application functional groups composed of acetyloxy groups, which interact with Cu. 2+The reaction forms a stable complex. The chromogenic agent used in this invention has good chemical and photostability, which ensures that the chromogenic agent maintains stable colorimetric properties under different environmental conditions (such as different temperatures and light conditions), avoiding the influence of environmental factors on the detection results and improving the accuracy and repeatability of the detection results.

[0041] The chromogenic reagent used in the detection method of this invention has sites that match divalent copper ions, enabling it to form stable complexes with divalent copper ions. This specific structural design significantly improves the sensitivity of the chromogenic reagent to divalent copper ions. When the concentration of divalent copper ions changes, the absorbance changes significantly, thereby achieving high-sensitivity detection of low concentrations of divalent copper ions. It not only has high sensitivity but is also easy to operate and has good stability, effectively detecting the content of divalent copper ions in water and providing a new solution for environmental monitoring.

[0042] Existing methods such as flame atomic absorption spectrophotometry and graphite furnace atomic absorption spectrophotometry have low detection limits and involve large-scale instruments, resulting in high costs, complex operations, and limited widespread adoption. Therefore, researching and developing novel, non-toxic, and highly sensitive spectrophotometric methods for the detection of copper is of great significance. The method of this invention can achieve highly sensitive detection of low concentrations of divalent copper ions. Furthermore, this method is simple to operate, highly stable, and can effectively determine the content of divalent copper ions in water, significantly outperforming the detection limits of existing methods. The colorimetric reagent is an environmentally friendly material, and no environmental pollution is generated during the detection process.

[0043] In this invention, tetraphenylporphyrin modified with acetoxy group (-OCOCH3) is selected as the copper ion colorimetric agent. The acetoxy group in this colorimetric agent molecule retains the mild characteristics of the ester group and provides an effective site for coordination reaction. Meanwhile, ester-based colorimetric agents and sulfonic acid-based colorimetric agents differ significantly in polarity, acidity / basicity, and solubility. Sulfonic acid groups are strongly acidic, strongly hydrophilic, and easily ionized, exhibiting excellent water solubility, but their free acid form is highly corrosive and has poor compatibility with organic phases. Ester groups, on the other hand, are neutral, mildly polar, and possess both good lipophilicity and moderate polarity. Their structure is flexible and tunable. Although their water solubility is not as good as sulfonic acid groups, the reaction conditions are mild and controllable, with low toxicity, low irritation, and minimal background interference. They also have significant advantages in compatibility with organic solvents, resins, and precision analytical systems.

[0044] In this invention, N,N-dimethylformamide (DMF) is used as the reaction medium in the spectrophotometric detection system for copper ions, which significantly improves detection sensitivity and lowers the method detection limit. DMF possesses excellent polarity and coordination properties, effectively solubilizing acetoxy-substituted porphyrin ligands and promoting their reaction with Cu. 2+ The rapid coordination reaction of DMF forms a stable colored chelate. Simultaneously, DMF inhibits the rapid coordination reaction of Cu... 2+Hydrolysis and polymerization side reactions enhance baseline stability. The auxochromic effect of the acetoxy group further enhances the molar absorptivity of the porphyrin conjugated system. The synergistic effect of these two factors significantly strengthens the detection signal, ultimately enabling the detection of trace Cu. 2+ Highly sensitive detection.

[0045] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0046] 1. The detection method of the present invention has a low detection limit, and can cause significant absorbance changes even at extremely low concentrations. The detection method of the present invention achieves Cu 2+ With a detection limit as low as 0.133 ug / L, it can be used for the simultaneous detection of trace Cu in environmental and industrial wastewater. 2+ This is of great significance for environmental protection and human health monitoring.

[0047] 2. The detection method of this invention has enhanced selectivity and can specifically react with Cu. 2+ The reaction combines well with good selectivity and high sensitivity, and is simple and convenient to operate.

[0048] 3. The specific detection method of this invention is simple to operate, fast detection (5 minutes), does not rely on large equipment and instruments, is simple to operate, short in time, efficient and convenient, and has no strict requirements on the detection environment and time, thus ensuring rapid determination. Attached Figure Description

[0049] Figure 1 This is the ultraviolet absorption spectrum of the colorimetric reagent of this invention;

[0050] Figure 2 The image shows the ultraviolet absorption spectrum of the colorimetric reagent and the divalent copper ion complex of this invention.

[0051] Figure 3 This is a graph showing the effect of surfactant type on the absorbance of the complex.

[0052] Figure 4 The graph shows the effect of Triton X-100 dosage on the absorbance of the complex.

[0053] Figure 5 The graph shows the effect of different pH values ​​on the absorbance of porphyrin copper ion complexes. The colorimetric reagent shows better complexation effect under acidic conditions.

[0054] Figure 6 The graph shows the effect of the amount of colorimetric reagent on the absorbance of the porphyrin copper ion complex.

[0055] Figure 7 The graph shows the effect of different temperatures on the absorbance of porphyrin copper ion complexes.

[0056] Figure 8This is a graph showing the effect of settling time on the absorbance of the complex.

[0057] Figure 9 Cu of the present invention 2+ Plotting of standard curve fitting between concentration (5~150ug / L) and absorbance;

[0058] Figure 10 This is the NMR spectrum of the chromogenic reagent. Detailed Implementation

[0059] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0060] Unless otherwise specified, all materials and reagents used in the following examples are commercially available. Experimental methods not specifically described in the examples are generally performed under standard conditions or as recommended by the manufacturer.

[0061] The specific configurations of each reagent in the examples are as follows:

[0062] Preparation method of colorimetric reagent solution: Weigh 40 mg of colorimetric reagent tetra(4-acetoxyphenyl)porphyrin, dissolve it in DMF, and prepare a 100 mL solution with a concentration of 400 mg / L.

[0063] Preparation of 0.3 mol / L hydrochloric acid solution: Use a pipette to transfer 2.5 ml of concentrated hydrochloric acid (mass fraction of 36-38%), and dilute with water to 100 ml to obtain a hydrochloric acid solution with a concentration of 0.3 mol / L.

[0064] Preparation of sodium dodecyl sulfate solution: Weigh 4g of solid and dissolve it in 40ml of water, then dilute to 100ml with water to obtain a 4% sodium dodecyl sulfate solution.

[0065] Preparation of Tween-80 solution: Measure 4 ml of Tween-80, pour it into a beaker, stir well with deionized water, transfer it to a volumetric flask and make up to 100 ml to obtain a 4% Tween-80 solution.

[0066] Preparation of hydroxylamine hydrochloride (hydroxyammonium chloride) solution: Weigh 4g of solid hydroxylamine hydrochloride, add 40ml of water to a beaker to dissolve it, transfer it to a volumetric flask, and make up to 100ml to obtain a 4% hydroxylamine hydrochloride solution.

[0067] Preparation of Triton X-100 solution: Measure 4 ml of Triton X-100, pour it into a beaker, stir well with deionized water, transfer it to a volumetric flask and make up to 100 ml to obtain a 4% Tween-80 solution.

[0068] Copper standard solution: Weigh 0.025g of anhydrous copper sulfate solid and dilute to 100ml in a volumetric flask. The resulting solution concentration is 100mg / L. Dilute to 1-5mg / L before use.

[0069] Anhydrous copper sulfate: analytical grade, Shanghai Bid Pharmaceutical Technology Co., Ltd., BD122189;

[0070] Tween-80: Chemically pure, Shanghai Bid Pharmaceutical Technology Co., Ltd., BD148605;

[0071] Sodium dodecyl sulfate (SDS): analytical grade, Shanghai Bid Pharmaceutical Technology Co., Ltd., BD151446;

[0072] Hydroxylamine hydrochloride: analytical grade, Shanghai Bid Pharmaceutical Technology Co., Ltd., BD105730;

[0073] Hydrochloric acid: analytical grade, Sinopharm Chemical Reagent Co., Ltd., 20250427;

[0074] Sulfuric acid: analytical grade, Sinopharm Chemical Reagent Co., Ltd., 20250408.

[0075] Example 1

[0076] In a round-bottom flask, 2 g of 4-hydroxybenzaldehyde, 3 mL of triethylamine, and 60 mL of anhydrous tetrahydrofuran were added sequentially. The mixture was stirred for 10 min under nitrogen protection. Then, 3 mL of acetyl chloride was slowly added dropwise. After the addition was complete, the mixture was stirred for another 30 min at room temperature under nitrogen protection. After the reaction was complete, the reaction mixture was filtered, and the solid was washed with tetrahydrofuran until nearly white. The solid was discarded, and the brown filtrate was collected. The filtrate was distilled under reduced pressure to remove the solvent, yielding a brown oil. This oil was dissolved in 10 mL of dichloromethane and washed sequentially with 20 mL of saturated sodium bicarbonate solution and 20 mL of distilled water. This washing process was repeated 1–2 times. The organic phase was collected and dried over anhydrous magnesium sulfate for later use. 1.313 g of 4-ethoxybenzaldehyde was added to the dried oil, and the mixture was dissolved in 30 mL of propionic acid. The mixture was refluxed at 150 °C for 30 min. After the reaction was complete, the mixture was cooled to room temperature, and the precipitated solid was filtered off. The solid was washed with methanol until the filtrate was colorless, yielding the target product. The product purity was determined to be 85%, and the reaction yield was 60%. The NMR spectrophotometer of the chromogenic reagent prepared in this example is shown below. Figure 10 The results of NMR characterization of the obtained products are as follows: 1H NMR (400 MHz, Chloroform-d) δ 8.90 (d, J = 4.1 Hz, 8H), 8.32 – 8.10 (m, 8H), 7.60 – 7.44 (m, 8H), 0.11 (s, 12H), -2.79 (s, 2H).

[0077] Example 2

[0078] The application of tetra(4-acetoxyphenyl)porphyrin chromogenic reagent in the detection of copper ions includes the following steps:

[0079] (1) The tetra(4-acetyloxyphenyl)porphyrin prepared in Example 1 showed an absorption peak at 419 nm under UV-Vis spectrophotometry (e.g., Figure 1 As shown), when 1 mL of 1 mg / L copper ion standard solution is added to 1 mL of 400 mg / L colorimetric reagent solution, an orange-yellow complex is formed, and a new absorption peak is generated at 451 nm (as shown). Figure 2 (As shown).

[0080] (2) Determination of surfactants: Four different types of surfactant solutions (4% each) were prepared: Tween-80, sodium dodecyl sulfate, hydroxylamine hydrochloride, and Triton X-100. 1 ml of each surfactant was taken, and 1 ml of 1 mg / L copper standard solution and 1 ml of 400 mg / L colorimetric reagent solution were added to each solution. 0.3 mol / L hydrochloric acid solution was added until the pH of the system reached 4.7, and the volume was adjusted to 10 ml with DMF. After standing at room temperature for 5 min, the solution was measured using a UV spectrophotometer. A surfactant-free porphyrin metal complex solution was used as a control. Figure 3 As shown, the absorbance of the porphyrin metal complex containing sodium dodecyl sulfate and Triton X-100 surfactant was significantly higher than that of the control group without surfactant, especially the Triton X-100 surfactant. However, hydroxylamine hydrochloride and Tween-80 had an inhibitory effect on the complex system. Finally, 4% Triton X-100 was selected as the surfactant.

[0081] (3) Take 0.2 mL, 0.5 mL, 0.75 mL, 0.8 mL, and 1.0 mL of 4% Triton X-100, respectively, and add 1 mL of 1 mg / L copper standard solution and 1 mL of 400 mg / L colorimetric reagent solution to each. Add 0.3 mol / L hydrochloric acid solution until the pH of the system is 4.7, and then dilute to 10 mL with DMF. After standing at room temperature for 5 min, perform the determination using a UV spectrophotometer. The results show that: Figure 4As shown, the absorbance is highest and most stable when the dosage of 4% sodium dodecyl sulfate is 0.8 mL. Therefore, the optimal dosage of 4% Triton X-100 is 0.8 mL.

[0082] (4) pH determination: Take 0.8 mL of 4% Triton X-100, add 1 mL of 1 mg / L copper standard solution and 1 mL of 400 mg / L colorimetric reagent solution, respectively, and add 0.3 mol / L hydrochloric acid solution until the pH of the system is at different acidity or alkalinity. Then, dilute to 10 mL with DMF. After standing at room temperature for 5 min, determine the pH using a UV spectrophotometer. The results show that: Figure 5 As shown, the absorbance is the highest and most stable in an acidic system, especially when the pH is adjusted to 4.7, the absorbance of the complex is the highest.

[0083] (5) Following the optimal method in step (4) above, adjust the dosage of the colorimetric reagent to 0.2~1.0 mL, such as... Figure 6 As shown, the absorbance value is the highest when the amount of colorimetric reagent is 1 mL.

[0084] (6) Following the optimal method in step (5) above, adjust the reaction temperature to 10~60℃, such as... Figure 7 As shown, the absorbance increases to its maximum when the reaction temperature is 25℃.

[0085] (7) Following the optimal method in step (6) above, adjust the static reaction time to 5~30 min, such as Figure 8 As shown, when the reaction time reaches 5 minutes, the absorbance increases to its maximum and tends to stabilize.

[0086] Example 3

[0087] The absorbance of mixed solutions of copper ions and colorimetric reagent at different concentrations was determined by spectrophotometry, and a colorimetric reagent solution of equal concentration was used as a blank control. Following the optimal method in step (7) of Example 2, the absorbance difference between the system solutions containing different concentrations of divalent copper ions and the blank control system solution was plotted as the ordinate, and the concentration of divalent copper ions as the abscissa to construct a standard curve; Figure 9 As shown, a standard curve was plotted using the absorbance of solutions containing different concentrations of divalent copper ions as the ordinate and the concentration of divalent copper ions as the abscissa. The standard curve equation for the divalent copper ion concentration range of 5–150 μg / L was y = 0.06749 + 85.12508x, R0. 2 =0.99617; apparent molar absorptivity ε=7.63×105 L / (mol·cm); detection limit for divalent copper ions is 0.133 ug / L.

[0088] Example 4

[0089] To verify the recovery rate of this method in actual samples, the optimal method in step (7) of Example 2 was used to detect Cu in actual water samples using the tetrakis(4-acetoxyphenyl)porphyrin colorimetric system. 2+ The testing was conducted using three water samples: sample 1, from pickling waste liquid of iron parts from a chemical plant; sample 2, from chemical nickel wastewater from a chemical plant; and sample 3, from high-phosphorus wastewater from an electroplating plant. 50 mL of each sample was taken as the original solution, filtered through a 2 μm filter membrane, and used for analysis. The filtrate was colorless and transparent, with no interfering color, ensuring the accuracy of the colorimetric reaction. Samples containing 0 and 0.1 mg / L Cu were selected. 2+ Three water samples were spiked for recovery experiments. Two groups of samples were analyzed using the tetra(4-acetoxyphenyl)porphyrin colorimetric method and ICP-MS. As shown in Table 1, the recovery rate of this invention ranged from 94.0% to 106.0%. The method is accurate and reliable, and the measured values ​​showed good consistency with the ICP-MS method, making it suitable for rapid analysis and detection of trace copper ions in actual water samples.

[0090] Table 1. Recovery rate of actual samples

[0091]

[0092] Example 5

[0093] To determine the experimental error of this method, 10 identical test tubes were selected, and parallel experiments were conducted according to the optimal method in step (7) of Example 2, under the premise that the reagent addition amount, experimental temperature, and other conditions were completely consistent. The absorbance was measured by spectrophotometry, and the measured absorbance value was mapped to the standard curve of divalent copper ions to obtain the copper ion concentration of the sample to be tested (based on...). Figure 9 The experimental standard deviation S was calculated to be 0.00377 for 10 sets of data, and the relative standard deviation RSD was 2.15%, which is lower than the precision evaluation standard in the field of chemical analysis (RSD≤3.0%). This fully demonstrates that the experimental method has small operational error, good parallelism, repeatability and stability, and good reliability for practical application.

[0094] In summary: The current standard for copper ion spectrophotometric determination is "Determination of Copper in Water - DDTC Spectrophotometric Method" (HJ 485-2009). This method has a detection limit of 0.01 mg / L, resulting in low sensitivity. Furthermore, it requires extraction with carbon tetrachloride, which is cumbersome, time-consuming, and prone to environmental pollution and harm to human health. In addition, the chromogenic reagent has poor stability and a short color development time. Meanwhile, the current standard for electronic-grade water (GBT11446.1-2013) in the electronics and semiconductor industry limits copper ions to ≤0.2 ug / L. Existing methods cannot meet this requirement. The method of this invention has a detection limit of 0.133 ug / L for copper ions, which meets the above-mentioned trace copper ion detection requirements. Moreover, the porphyrin chromogenic reagent directly develops color with metal ions in the aqueous phase, eliminating the need for complex extraction operations. The complex formed by porphyrin and copper ions has good stability and a long color development time.

[0095] In summary, the detection method of the present invention has higher sensitivity and meets the industry's maximum limit requirements. The method of the present invention is simple, fast, and easy to promote and use.

Claims

1. A rapid spectrophotometric detection method for ultra-low concentration copper ions, characterized in that, Includes the following steps: (1) Add colorimetric reagent tetra(4-acetoxyphenyl)porphyrin and surfactant Triton X-100 to the sample to be tested, adjust the pH of the system to acidic, mix well and let it stand to react; (2) After the reaction is complete, the absorbance is measured by spectrophotometry. The measured absorbance value is then matched with the standard curve of divalent copper ions to obtain the copper ion concentration of the sample to be tested. The chromogenic agent tetra(4-acetoxyphenyl)porphyrin has the following structural formula: 。 2. The rapid spectrophotometric detection method for ultra-low concentration copper ions according to claim 1, characterized in that, In step (1), the concentration of the colorimetric reagent tetra(4-acetoxyphenyl)porphyrin is 300~400 mg / L, and the amount added is 0.2-1.0 mL.

3. The rapid spectrophotometric detection method for ultra-low concentration copper ions according to claim 1, characterized in that, In step (1), the amount of surfactant added is 0.2-1.4 mL, and the concentration is 1-5%.

4. The rapid spectrophotometric detection method for ultra-low concentration copper ions according to claim 1, characterized in that, In step (1), the pH of the system is adjusted by adding hydrochloric acid solution with a concentration of 0.2-0.3 mol / L to adjust the pH to 4-6.

5. The rapid spectrophotometric detection method for ultra-low concentration copper ions according to claim 4, characterized in that, In step (1), the pH is adjusted to 4 to 4.

7.

6. The rapid spectrophotometric detection method for ultra-low concentration copper ions according to claim 1, characterized in that, In step (1), the reaction time after mixing is 5-30 min and the reaction temperature is 10-60℃.

7. The rapid spectrophotometric detection method for ultra-low concentration copper ions according to claim 1, characterized in that, The medium used for the reaction after mixing and standing in step (1) is preferably N,N-dimethylformamide.

8. The rapid spectrophotometric detection method for ultra-low concentration copper ions according to claim 1, characterized in that, In step (2), the absorbance was measured by spectrophotometry, and the maximum absorption wavelength of divalent copper ions was 451 nm.

9. The rapid spectrophotometric detection method for ultra-low concentration copper ions according to claim 1, characterized in that, The detection environment for ultra-low concentration copper ions includes aquatic or soil environments.

10. The application of the chromogenic agent tetra(4-acetoxyphenyl)porphyrin used in the rapid spectrophotometric detection method for ultra-low concentration copper ions according to claim 1 in the rapid spectrophotometric detection method for copper ions in the environment.

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