Kit and method for determining concentration of copper ions in saline water

Abstract

The invention provides a kit and a method for determining the concentration of copper ions in saline water. The kit comprises a masking reagent, a color developing reagent, a standard constant volume reagent and a diluting reagent, the masking reagent comprises a buffer solution, a reducing agent and a masking agent; the color developing reagent comprises a color developing agent and an organic solvent; the Cu < 2 + > content in the standard constant volume reagent is 0; the salinity of the diluting reagent is the same as that of the saline water. According to the kit provided by the invention, through four-dimensional optimization of'sensitivity-interference resistance-convenience-environmental protection ', the problem of pain points of a traditional copper ion detection method in a saline water matrix is solved, and the kit becomes an ideal tool for rapid analysis of copper ions in a high-salt environment; besides, the determination method provided by the invention does not need to be operated by large-scale instruments and equipment and professionals, is simple and convenient to operate, can cope with sudden environmental pollution events or large-scale quality screening detection, and promotes standardization and popularization of an on-site detection technology.

Description

Technical Field

[0001] The invention belongs to the technical field of water quality detection and relates to a kit and a method for measuring the copper ion concentration in salt water. Background Art

[0002] In chemical production processes, brine is often used as raw material, cooling medium or reaction medium. 2+ The presence of Cu may have many effects on brine quality, production process and final product, causing equipment corrosion. 2+ It is oxidizing and can easily form micro batteries with metals in salt water, accelerating pitting or crevice corrosion of metal equipment. It will also cause the purity of salt water to decrease. When electrolyzing salt water, Cu 2+ It will be reduced to copper at the cathode, which will contaminate the caustic soda and chlorine products. 2+ It may be adsorbed on the surface of salt crystals, resulting in abnormal color or substandard purity of industrial salt products. 2+ It may catalyze oxidation or decomposition reactions in brine, affecting the stability of the electrolysis process.

[0003] Colorimetry is typically based on the fact that compounds generated by specific chemical reactions have absorption spectra at specific wavelengths. By measuring the absorbance at these wavelengths, the concentration of copper ions can be determined. When using colorimetry to determine copper ions, the first step is to select a suitable color developer. Commonly used color developers include disulfide hydrazone and diphenylcarbazide. These color developers react with copper ions to produce compounds of a specific color. During the experiment, the color of the resulting compound can be optimized by adjusting the concentration of the color developer and the reaction conditions. Colorimetry for determining copper ions has the advantages of ease of operation, low cost, and accurate results. However, this method also has certain limitations. For example, the choice of color developer and the optimization of reaction conditions have a significant impact on the experimental results, requiring precise control of the experimental conditions.

[0004] While atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS), and inductively coupled plasma spectrometry (ICP) offer accurate and reliable results, they require large-scale equipment and specialized personnel, resulting in lengthy analysis times and high costs. These methods are also limited in time and location, making them unsuitable for sudden environmental pollution incidents or large-scale quality screening. Existing methods for detecting heavy metal copper are costly, inefficient, and lack accuracy.

[0005] CN 117990686A discloses a copper ion detection test strip and its application. This method uses a PE-NC copper ion detection test strip prepared by loading phycoerythrin onto a nitrocellulose membrane. The synthesis method is simple and the cost is relatively low. The test strip requires only operator training on a small portable spectrophotometer for use. After successful loading of phycoerythrin onto the nitrocellulose membrane, it exhibits high specificity for copper ions. Specificity testing revealed that other metal ions do not produce significant color differences. However, this method does not account for interference with the test caused by high chloride ion concentrations, other salts, and pH values ​​in saline. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the present invention aims to provide a kit and method for measuring the copper ion concentration in salt water. The kit can test the copper ion concentration in salt water and has the advantages of high testing efficiency and high accuracy.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] The present invention provides a kit for measuring the copper ion concentration in salt water, the kit comprising a masking reagent, a color developing reagent, a standard volume fixing reagent, and a diluting reagent;

[0009] The masking reagent includes a buffer solution, a reducing agent and a masking agent; the color developing reagent includes a color developing agent and an organic solvent; the standard constant volume reagent contains Cu 2+ The content is 0; the salinity of the dilution reagent is the same as that of the brine.

[0010] The kit provided by the present invention can be used to quickly and accurately determine the concentration of copper ions in salt water; wherein the masking reagent is used to mask the Cl in the salt water to be measured. - 、SO4 2- , Ca 2+ Mg 2+ 、Fe 3+ 、Sr 2+ 、Ba 2+ Interfering ions such as copper ions; the color developing reagent can combine with cuprous ions to form a color developing complex; the standard volume fixing reagent is used to prepare the working curve standard solution to avoid matrix effects; and provides a standard working curve to provide data support for the subsequent calculation of the copper ion content in the brine to be tested; the diluting reagent is used to dilute the high-concentration brine to be tested to ensure that the chloride ion and sulfate ion strengths in the brine remain substantially unchanged, further determining the accuracy of the copper ion concentration calculation;

[0011] More specifically, the buffer solution in the masking agent can maintain the pH value of the masking agent, making it more effective in a salt water environment to resist the pH change caused by high chloride ions, and the reducing agent can reduce the pH value of Cu 2+Reduction to Cu + , to resist the pH change caused by high chloride ions, the masking agent can mask the influence of other ions in the brine on copper ions; therefore, the accurate determination of the copper ion concentration in the brine can be achieved through the synergistic effect of the masking reagent, the colorimetric reagent, the standard volume-fixing reagent and the dilution reagent.

[0012] In the present invention, the salt water contains the following ions: Ca 2+ Mg 2+ 、Fe 3+ 、Cu 2+ 、Sr 2+ 、Ba 2+ 、Cl - and SO4 2- ;

[0013] Among them, the Ca 2+ The concentration is 0.8 to 3.0 mg / L, for example, 0.8 mg / L, 1.2 mg / L, 1.6 mg / L, 2.0 mg / L, 2.4 mg / L or 3.0 mg / L, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable;

[0014] The Mg 2+ The concentration is 0.1 to 0.5 mg / L, for example, 0.1 mg / L, 0.3 mg / L, 0.4 mg / L or 0.5 mg / L, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0015] The Fe 3+ The concentration is 0.1 to 0.5 mg / L, for example, 0.1 mg / L, 0.3 mg / L, 0.4 mg / L or 0.5 mg / L, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0016] The Cu 2+ The concentration is 0.5 to 600 mg / L, for example, 0.5 mg / L, 20 mg / L, 50 mg / L, 100 mg / L, 300 mg / L or 600 mg / L, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0017] The Sr 2+ The concentration is 0.1 to 0.5 mg / L, for example, 0.1 mg / L, 0.3 mg / L, 0.4 mg / L or 0.5 mg / L, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0018] The Ba 2+The concentration is 0.5 to 1.0 mg / L, for example, 0.5 mg / L, 0.7 mg / L, 0.9 mg / L or 1.0 mg / L, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable;

[0019] The Cl - The concentration is 290 to 320 g / L, for example, 290 g / L, 300 g / L, 310 g / L or 320 g / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable;

[0020] The SO4 2- The concentration is 3 to 6 g / L, for example, 3 g / L, 4 g / L, 5 g / L or 6 g / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0021] As a preferred technical solution of the present invention, the pH value of the masking reagent is 4 to 6, for example, it can be 4, 4.4, 4.8, 5.2, 5.6 or 6, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0022] Preferably, the masking agent comprises Cl - Masking agents and metal ion masking agents.

[0023] Preferably, in terms of mass fraction, the masking agent comprises: Cl - The masking agent is 0.45-0.55 wt%, the metal ion masking agent is 0.08-0.12 wt%, the reducing agent is 4.5-5.5 wt%, and the balance is buffer solution.

[0024] More specifically, the Cl in the masking reagent - The content of the masking agent is 0.45 to 0.55 wt%, for example, 0.45 wt%, 0.48 wt%, 0.52 wt% or 0.55 wt%, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0025] The content of the metal ion masking agent in the masking agent is 0.08 to 0.12 wt %, for example, 0.08 wt %, 0.09 wt %, 0.1 wt % or 0.12 wt %, but is not limited to the values ​​listed, and other values ​​not listed within the numerical range are also applicable;

[0026] The content of the reducing agent in the masking reagent is 4.5-5.5 wt%, for example, 4.5 wt%, 4.8 wt%, 5.1 wt% or 5.5 wt%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] Preferably, the buffer solution comprises acetic acid-sodium acetate solution.

[0028] Preferably, the concentration of the acetic acid-sodium acetate solution is 0.45 to 0.55 mol / L, for example, 0.45 mol / L, 0.47 mol / L, 0.49 mol / L, 0.51 mol / L or 0.55 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0029] Preferably, the Cl - Masking agents include thiourea and / or potassium thiocyanate, preferably thiourea

[0030] In the present invention, the chloride ions in the salt water are easily reacted with Cu in a high salt environment. + Combined to form CuCl2 complex, reducing the color development efficiency, the present invention uses Cl - Masking agents preferentially react with Cu + Binding, blocking Cl - interference to further improve the color rendering efficiency.

[0031] Preferably, the metal ion masking agent comprises any one or a combination of at least two of EDTA, ammonium citrate, ascorbic acid or potassium sodium tartrate. Typical but non-limiting combinations include: a combination of EDTA and ammonium citrate, a combination of ascorbic acid and potassium sodium tartrate, a combination of EDTA, ammonium citrate and ascorbic acid, or a combination of EDTA, ammonium citrate, ascorbic acid and potassium sodium tartrate, preferably EDTA.

[0032] In the present invention, the metal ion masking agent can be used to mask the Ca 2+ Mg 2+ 、Fe 3+ 、Sr 2+ 、Ba 2+ ion.

[0033] Preferably, the reducing agent comprises hydroxylamine hydrochloride.

[0034] As a preferred technical solution of the present invention, the developer includes any one of disulfide hydrazone, diphenylcarbohydrazide or neocuproine, or a combination of at least two of them. Typical but non-limiting combinations include: a combination of disulfide hydrazone and diphenylcarbohydrazide, a combination of disulfide hydrazone and neocuproine, a combination of diphenylcarbohydrazide and neocuproine, or a combination of disulfide hydrazone, diphenylcarbohydrazide and neocuproine, preferably neocuproine.

[0035] Preferably, the organic solvent comprises an ethanol solution.

[0036] Preferably, the content of the developer in the developer is 0.1-0.2 wt%, for example, 0.1 wt%, 0.14 wt%, 0.17 wt% or 0.2 wt%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0037] Preferably, the content of ethanol solution in the color developing reagent is 48-52wt%, for example, it can be 48wt%, 49wt%, 50wt%, 51wt% or 52wt%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0038] In the present invention, if the concentration of the color developer is too low, it will lead to incomplete color development and insufficient sensitivity; if the concentration is too high, it will cause an increase in background absorbance; in addition, by controlling the content of the ethanol solution, it can avoid excessive volatilization or insufficient dissolution.

[0039] In the present invention, the masking reagent and the color developing reagent are both stored in brown bottles in the dark.

[0040] As a preferred technical solution of the present invention, in addition to Cu 2+ In addition, the composition of the standard volume-fixing reagent is the same as that of the saline to be tested.

[0041] Preferably, Cl in the dilution reagent - and SO4 2- The content is the same as that of the brine to be tested.

[0042] In a second aspect, the present invention provides a method for determining the concentration of copper ions in salt water, wherein the method is performed using the kit for determining the concentration of copper ions in salt water provided in the first aspect.

[0043] As a preferred technical solution of the present invention, the determination method provided in the second aspect of the present invention comprises the following steps:

[0044] (1) Prepare several standard solutions using standard volume reagents, then sequentially mix the masking reagent and the colorimetric reagent, and determine the absorbance before establishing the Cu concentration of the standard solution. 2+ Concentration-absorbance relationship curve;

[0045] (2) diluting the saline solution to be tested with a diluting reagent to obtain a mixed solution, and then sequentially mixing a masking reagent and a color developing reagent to obtain a mixed solution to be tested;

[0046] (3) The absorbance of the mixed solution to be tested is measured to obtain the absorbance A0 of the mixed solution to be tested, and the absorbance A0 is substituted into the Cu obtained in step (1). 2+ In the concentration-absorbance relationship curve, the Cu 2+ concentration.

[0047] Preferably, the preparation method of the standard solution in step (1) comprises: adding AmL, BmL, CmL, DmL, EmL, and FmL of a 1000mg / L copper standard working solution to a volumetric flask, respectively, and then using a standard volume-fixing reagent to adjust the volume to the standard scale of the volumetric flask to obtain a standard solution; wherein A<B<C<D<E<F, and A=0.

[0048] Preferably, the volume ratio of the masking reagent, the color developing reagent and the standard solution in step (1) is 4 to 6:0.8 to 1.2:10, for example, it can be 4:0.8:10, 5:1:10, 6:1.2:10 or 5:1.1:10, etc., but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0049] Preferably, the Cu of the standard solution in step (1) 2+ The linear relationship of the concentration-absorbance curve is: A=mc(Cu 2+ )+n, where m and n are constants, A is the absorbance, c(Cu 2+ ) is the copper ion concentration.

[0050] Preferably, in step (2), when the Cu 2+ When the concentration is 0.5-10 mg / L, no dilution is performed;

[0051] Preferably, when the Cu 2+ When the concentration is 10 to 100 mg / L, the dilution multiple of the dilution treatment is 5 to 10 times, for example, it can be 5 times, 6 times, 7 times, 8 times, 9 times or 10 times, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0052] Preferably, when the Cu 2+ When the concentration is greater than 100 mg / L, the dilution factor of the dilution treatment is 15 to 25 times, for example, 15 times, 17 times, 19 times or 25 times, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0053] Preferably, the volume ratio of the masking reagent, the color developing reagent and the mixed solution in step (2) is 4 to 6:0.8 to 1.2:10, for example, it can be 4:0.8:10, 5:1:10, 6:1.2:10 or 5:1.1:10, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0054] Preferably, after mixing the masking reagents in step (1) and step (2), shake well and let it stand for 1.5 to 2.5 minutes, for example, it can be 1.5 minutes, 1.7 minutes, 1.9 minutes, 2.1 minutes, 2.3 minutes or 2.5 minutes, etc., but it is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0055] Preferably, after mixing the color developing reagents in step (1) and step (2), shake well and let it stand for 7 to 15 minutes, for example, it can be 7 minutes, 8 minutes, 9 minutes, 14 minutes or 15 minutes, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0056] Preferably, the wavelength used for absorbance measurement obtained in step (1) and step (3) is 400 to 500 nm, for example, 400 nm, 420 nm, 440 nm, 460 nm, 480 nm or 500 nm, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0057] Preferably, the salt water Cu 2+ The concentration is calculated as follows:

[0058] c(Cu 2+ , saline) = dilution factor × (A0-n) ÷ m.

[0059] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] (1) The kit for determining the copper ion concentration in salt water provided by the present invention can realize the rapid determination of the copper ion concentration in salt water;

[0062] (2) The present invention solves the pain points of traditional copper ion detection methods in salt water matrices, such as Cl, through the four-dimensional optimization of "sensitivity-anti-interference-convenience-environmental protection" through the kit for determining the copper ion concentration in salt water. - , Ca 2+ Mg 2+ 、Fe 3+ 、Sr 2+ 、Ba 2+ 、SO4 2- Ion interference makes it an ideal tool for rapid analysis of copper ions in high salt environments;

[0063] (3) The present invention does not require large-scale equipment and professional personnel to operate, such as traditional atomic absorption spectrometry or ICP-MS. It is easy to operate and can respond to sudden environmental pollution incidents or large-scale quality screening and detection, promoting the standardization and popularization of on-site detection technology;

[0064] (4) Cu of the standard solution established by the present invention 2+ R of the concentration-absorbance relationship curve 2 The values ​​were all higher than 0.999. The determination of copper ion concentration in salt water had good linear correlation under this analytical method, which met the control requirements of GB / T27404-2008 "Laboratory Quality Control Specification for Physical and Chemical Testing of Food". The measurement results were accurate and could be used for routine testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 The Cu of the standard solution provided in Application Example 1 of the present invention is 2+ Concentration-absorbance relationship curve. DETAILED DESCRIPTION

[0066] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0067] The impurity ion content in the brine to be tested provided in the following application examples and comparative application examples is: Ca 2+ :(0.8-3.0mg / L), Mg 2+ :(0.1-0.5mg / L), Fe 3+ :(0.1-0.5mg / L),Cu 2+ :(0.5-600mg / L), Sr 2+ :(0.1-0.5mg / L), Ba 2+ :(0.5-1.0mg / L), Cl - :(290-320g / L), SO4 2- :(3-6g / L).

[0068] Example 1

[0069] This embodiment provides a kit for determining the concentration of copper ions in saline, the kit comprising a masking reagent, a colorimetric reagent, a standard volume-fixing reagent, and a diluting reagent;

[0070] The masking reagent includes a buffer solution, a reducing agent and a masking agent; the color developing reagent includes a color developing agent and an organic solvent; the standard constant volume reagent contains Cu 2+ The content is 0; the salinity of the dilution reagent is the same as that of the brine.

[0071] The pH value of the masking agent is 5; the masking agent includes Cl - Masking agent and metal ion masking agent; in terms of mass fraction, the masking agent includes: Cl - 0.5wt% masking agent, 0.1wt% metal ion masking agent, 5wt% reducing agent, and the balance is buffer solution;

[0072] The buffer solution includes acetic acid-sodium acetate solution; the concentration of the acetic acid-sodium acetate solution is 0.5 mol / L; the Cl - The masking agent is thiourea; the metal ion masking agent is EDTA; and the reducing agent is hydroxylamine hydrochloride.

[0073] The color developing agent is neocuproine; the organic solvent is an ethanol solution; the content of the color developing agent in the color developing reagent is 0.1 wt%; the content of the ethanol solution in the color developing reagent is 50 wt%.

[0074] Example 2

[0075] This embodiment provides a kit for determining the concentration of copper ions in salt water. The difference between the kit and Example 1 is that:

[0076] In this embodiment, the content of the color developing agent in the color developing reagent is adjusted to 0.05 wt %.

[0077] Example 3

[0078] This embodiment provides a kit for determining the concentration of copper ions in salt water. The difference between the kit and Example 1 is that:

[0079] In this example, the pH value of the masking reagent was adjusted to 7.

[0080] Example 4

[0081] This example provides a kit for determining the copper ion concentration in salt water. The difference between the kit and Example 1 is that:

[0082] In this embodiment, the reducing agent in the masking reagent is omitted.

[0083] Comparative Example 1

[0084] This embodiment provides a kit for determining the concentration of copper ions in salt water. The difference between the kit and Example 1 is that:

[0085] In this comparative example, the masking agent and the buffer solution in the masking reagent were omitted.

[0086] Application Example 1

[0087] This application example provides a method for determining the concentration of copper ions in salt water. The determination method is performed using the kit for determining the concentration of copper ions in salt water described in Example 1.

[0088] This application example measures the copper ion content of three types of brine. The copper ion content of brine A ranges from 10 to 100 mg / L, the copper ion content of brine B ranges from 0.5 to 10 mg / L, and the copper ion content of brine C ranges from 100 to 600 mg / L.

[0089] The measuring method comprises the following steps:

[0090] (1) Prepare standard solutions with concentration gradients of 0, 2, 5, 10, 20, 30, and 40 mg / L using standard constant volume reagents, and establish the Cu 2+ Concentration-absorbance relationship curve (such as Figure 1 The specific steps are as follows:

[0091] a. 1000 mg / L copper standard working solution: Accurately weigh 2.6826 g of cupric chloride reagent into a 1000 mL volumetric flask, dilute to the mark with pure water, and mix thoroughly.

[0092] b. 0mg / L standard solution: the standard volume reagent is standard solution 0#;

[0093] c. 2 mg / L standard solution: Pipette 0.2 mL of copper standard working solution (1000 mg / L) and transfer it to a 100 mL volumetric flask. Dilute to the mark with standard dilution reagent and mix thoroughly to obtain standard solution #1.

[0094] d. 5 mg / L standard solution: Pipette 0.5 mL of the copper standard working solution (1000 mg / L) into a 100 mL volumetric flask, dilute to the mark with the standard dilution reagent, and mix thoroughly to obtain standard solution #2.

[0095] e. 10 mg / L standard solution: Pipette 1.0 mL of copper standard working solution (1000 mg / L) and transfer it to a 100 mL volumetric flask. Dilute to the mark with standard dilution reagent and mix thoroughly to obtain standard solution #3.

[0096] f. 20 mg / L standard solution: Pipette 2.0 mL of copper standard working solution (1000 mg / L) and transfer it to a 100 mL volumetric flask. Dilute to the mark with standard dilution reagent and mix thoroughly to obtain standard solution #4.

[0097] g. 30 mg / L standard solution: Pipette 3.0 mL of copper standard working solution (1000 mg / L) and transfer it to a 100 mL volumetric flask. Dilute to the mark with standard dilution reagent and mix thoroughly to obtain standard solution #5.

[0098] h. 40 mg / L standard solution: Pipette 4.0 mL of copper standard working solution (1000 mg / L) and transfer it to a 100 mL volumetric flask. Dilute to the mark with standard dilution reagent and mix thoroughly to obtain standard solution #6.

[0099] Then, take 10 mL of the above 0#, 1#, 2#, 3#, 4#, 5#, and 6# standard solutions respectively and add them into 50 mL colorimetric tubes, add 5 mL of masking reagent, shake well and let stand for 2 minutes, add 1 mL of colorimetric reagent, shake well and let stand at room temperature for 8 minutes;

[0100] Then, adjust the zero point with pure water and use a 1 cm cuvette to measure the absorbance of standard solution 0#, 1#, 2#, 3#, 4#, 5#, and 6# samples at a wavelength of 450 nm, as shown in Table 1:

[0101] Table 1

[0102]

[0103]

[0104] Finally, the copper ion concentration in the salt water is taken as the horizontal axis (mg / L) and the absorbance is taken as the vertical axis (ABS), and the corresponding working curve A=0.0054c(Cu 2+ )+0.008,R 2 =0.9994, such as Figure 1 shown.

[0105] (2) Using a diluting reagent to dilute the salt water to be tested to obtain a mixed solution, and then sequentially mixing a masking reagent and a color developing reagent to obtain a mixed solution to be tested. The specific steps are as follows:

[0106] First, prepare the brine to be tested, which includes brine A, brine B, brine C (respectively denoted as A0#, B0#, C0#) and spiked brine; wherein the spiked brine includes A1#, A2#, B1#, B2#, C1# and C2# samples.

[0107] The preparation method of the spiked brine comprises:

[0108] A1# sample: Accurately pipette 1.00 mL of copper standard working solution (1000 mg / L) into a 100 mL volumetric flask, dilute to the mark with A0# saline sample, and shake well. The theoretical copper content of this solution should be (A0# sample value + 10) mg / L.

[0109] Sample A2: Accurately transfer 2.00 mL of copper standard working solution (1000 mg / L) to a 100 mL volumetric flask. Add the copper salt solution sample A0 to the mark and shake well. The theoretical copper content of this solution should be (sample A0 value + 20) mg / L.

[0110] B1# sample: Accurately pipette 1.00 mL of copper standard working solution (1000 mg / L) into a 100 mL volumetric flask. Add B0# copper salt water sample to the mark and shake well. The theoretical copper content of this solution should be (B0# sample value + 10) mg / L.

[0111] B2# sample: Accurately transfer 2.00 mL of copper standard working solution (1000 mg / L) to a 100 mL volumetric flask. Add B0# copper salt solution to the mark and shake well. The theoretical copper content of this solution should be (B0# sample value + 20) mg / L.

[0112] C1# sample: Accurately pipette 10.00 mL of copper standard working solution (1000 mg / L) into a 100 mL volumetric flask. Add C0# copper salt water sample to the mark and shake well. The theoretical copper content of this solution should be (C0# sample value + 100) mg / L.

[0113] Sample C2: Accurately transfer 20.00 mL of the copper standard working solution (1000 mg / L) to a 100 mL volumetric flask. Add the copper salt solution from sample C0 to the mark and shake well. The theoretical copper content of this solution should be (sample C0 + 200) mg / L.

[0114] Next, prepare the mixed solution to be tested:

[0115] a. For samples A0#, A1#, and A2#: Take 10 mL of sample and add it to a colorimetric tube. Add 5 mL of masking reagent, shake well, and let it stand for 2 minutes to reduce Cu 2+ Cu + , while masking interference, add 1mL of color reagent, shake well and let stand at room temperature for 8 minutes, the solution turns orange-yellow;

[0116] b. For samples B0#, B1#, and B2#: Take 1 mL of sample and 9 mL of dilution reagent and add them to a colorimetric tube. Add 5 mL of masking reagent, shake well, and let it stand for 2 minutes to reduce Cu 2+ Cu + , while masking interference; then add 1mL of color reagent, shake well and let it stand at room temperature for 8 minutes, the solution turns orange-yellow;

[0117] c. For C0#, C1#, and C2# samples: Take 0.5 mL of sample and 9.5 mL of dilution reagent and add them to the colorimetric tube. Add 5 mL of masking reagent, shake well, and let it stand for 2 minutes to reduce Cu 2+ Cu+ , while masking interference; then add 1mL of color reagent, shake well and let it stand at room temperature for 15 minutes, and the solution turns orange-yellow.

[0118] (3) The absorbance of the mixed solution to be tested is measured to obtain the absorbance A0 of the mixed solution to be tested, and the absorbance A0 is substituted into the Cu obtained in step (1). 2+ In the concentration-absorbance relationship curve, the Cu 2+ Concentration, the calculation formulas are as follows, and the sample test data are shown in Table 2;

[0119] A0# sample: C(Cu 2+ )=(A0-0.008) / 0.0054;

[0120] A1# sample: C(Cu 2+ )=(A0-0.008) / 0.0054+10;

[0121] A2# sample: C(Cu 2+ )=(A0-0.008) / 0.0054+20;

[0122] B0# sample: C(Cu 2+ )=10(A0-0.008) / 0.0054;

[0123] B1# sample: C(Cu 2+ )=10(A0-0.008) / 0.0054+10;

[0124] B2# sample: C(Cu 2+ )=10(A0-0.008) / 0.0054+20;

[0125] C0# sample: C(Cu 2+ )=20(A0-0.008) / 0.0054;

[0126] C1# sample: C(Cu 2+ )=20(A0-0.008) / 0.0054+100;

[0127] C2# sample: C(Cu 2+ )=20(A0-0.008) / 0.0054+200;

[0128] Table 2

[0129]

[0130]

[0131] As shown in Table 2, the relative ranges of the six test results all met the quality control requirement that the average value of the measurement results obtained under repeated conditions should not exceed 10% of the arithmetic mean value; the coefficient of variation of the test results all met the control requirement of ≤3.8%.

[0132] The spiked recovery of brine was calculated based on the data (average value) in Table 2. The results are shown in Table 3:

[0133] Table 3

[0134]

[0135] According to Table 3, the method provided by the present invention can meet the internal quality control requirement of spiked recovery rate of 95% to 105%.

[0136] Application Examples 2-4

[0137] Application Examples 2-4 respectively provide a method for determining the concentration of copper ions in salt water, and the determination method is performed using the kit for determining the concentration of copper ions in salt water provided in Examples 2-4.

[0138] Compared with Application Example 1, the low content of the colorimetric reagent in Application Example 2 will lead to sensitivity and linear failure, which in turn will cause a large deviation between the calculated copper ion concentration and the actual concentration; when the pH value of the masking reagent in Application Example 3 is high, Cl - The binding ability of the masking agent to cuprous ions decreases sharply, Cl - Interference is aggravated; the reducing ability of the reducing agent decreases when pH>6, the trivalent iron ions cannot be fully reduced, and the reducing agent is consumed competitively and the cuprous ions are oxidized, resulting in a low copper ion recovery rate, which makes the measured value lower than the actual concentration; when the reducing agent in the masking reagent is omitted in Application Example 4, the reaction cannot continue, and thus the standard working curve cannot be obtained, and the copper ion concentration in the brine to be tested cannot be known.

[0139] Comparative Application Example 1

[0140] This comparative example provides a method for determining the concentration of copper ions in salt water. The method is performed using the kit for determining the concentration of copper ions in salt water described in Comparative Example 1.

[0141] The salt water to be tested and the determination method of this comparative application example are the same as those of Application Example 1. The determination results of copper ions in the samples are shown in Table 4.

[0142] Table 4

[0143]

[0144]

[0145] As shown in Table 4, the relative range of the copper ion concentration of the salt water measured by the kit provided in Comparative Example 1 does not meet the quality control requirement that the average value of the measurement results meets the absolute value of the difference between two independent measurement results obtained under repeated conditions does not exceed 10% of the arithmetic mean; in addition, the coefficient of variation does not meet the control requirement of ≤3.8%.

[0146] The spiked recovery of brine was calculated based on the data (average value) in Table 4, and the results are shown in Table 5:

[0147] Table 5

[0148]

[0149] According to Table 5, the recovery rate of spiked samples using the kit provided in Comparative Example 1 does not meet the internal quality control requirement of 95-105%.

[0150] Comparative Application Example 2

[0151] This comparative application example provides a method for determining the copper ion content in salt water using the ICP method.

[0152] The instruments used in the ICP method include: plasma emission spectrometer: ICAP6300, analysis software: ITEVA, and sampling system: EMT sampling system;

[0153] Reagents and preparations include: copper standard solution;

[0154] The instrument conditions were as follows: pump speed: 50 rpm, RF generator power: 1150 w, auxiliary gas flow rate: 0.5 L / min, nebulizer working pressure: 0.2 MPa, vertical observation height: 12 mm, wavelength: 324.7 nm.

[0155] Methods for determining copper ions in salt water include:

[0156] 1. The method for determining the copper ion content in salt water A by ICP method comprises the following steps:

[0157] Prepare three 50mL volumetric flasks (K0, K1, and K2). Pipette 0mL, 1mL, and 2mL of a 10mg / L copper standard solution into each of these flasks, respectively. Pipette 10mL of brine into each of these flasks, dilute to the mark with ultrapure water, and shake well. Determine the copper content of the brine using the standard addition method.

[0158] Sample #0: Accurately transfer 10.00 mL of copper standard stock solution copper salt sample into a 50 mL volumetric flask, dilute to the mark with ultrapure water, and shake well.

[0159] Sample #1: Accurately pipette 1.00 mL of the copper standard stock solution (10 mg / L) into a 50 mL volumetric flask. Add the copper salt solution to the mark and shake well. The theoretical copper content of this solution should be (sample value + 200) μg / L.

[0160] Sample #2: Accurately transfer 2.00 mL of the copper standard stock solution (10 mg / L) to a 50 mL volumetric flask. Add the copper salt solution to the mark and shake well. The theoretical copper content of this solution should be (sample value + 400) μg / L.

[0161] 2. The method for determining the copper ion content in salt water B and C by ICP method includes the following steps:

[0162] Prepare five 50mL volumetric flasks K0, K1, K2, K3, and K4, and transfer 0mL, 1mL, 2mL, 3mL, and 4mL of copper standard solution (1000mg / L) into the K0, K1, K2, K3, and K4 volumetric flasks respectively. Add ultrapure water to the scale, shake well, and determine the copper content of the brine using the standard curve method.

[0163] Copper Brine Sample: Accurately pipette 5.00 mL of copper standard stock solution (1 mg / L) into a 100 mL volumetric flask. Add the copper brine sample to the mark and shake well. The theoretical copper content of this solution should be (sample value + 50) μg / L.

[0164] Sample #2: Accurately transfer 10.00 mL of the copper standard stock solution (1 mg / L) to a 100 mL volumetric flask. Add the copper salt solution to the mark and shake well. The theoretical copper content of this solution should be (sample value + 100) μg / L.

[0165] Finally, the analysis results were directly read out using ITEVA software and retained to one decimal place; the measurement result = read value × dilution factor.

[0166] The results of measuring the copper ion content in salt water using the methods provided in Application Example 1 and Comparative Application Examples 1-2 are shown in Table 6.

[0167] Table 6

[0168]

[0169] Comprehensive analysis of Tables 2-6 shows that the kit and assay method provided by the present invention meet the quality control requirement that the relative range of the mean value of the test results obtained under repeated conditions should not exceed 10% of the arithmetic mean, and the coefficient of variation meets the control requirement of ≤3.8%. The spiked recovery also meets the quality control requirement of 95% to 105%. Therefore, the kit and assay method provided by the present invention meet the control requirements for test methods in the national standard GB / T 27404-2008, "Laboratory Quality Control Specification for Physical and Chemical Testing of Foods."

[0170] At the same time, the copper content in the brine was analyzed using the kit provided by the present invention and the ICP method. Under the same analysis conditions and the same instrument conditions, the relative deviations of the method provided by the present invention relative to the ICP method were 4.55%, 3.16%, and 1.27%, respectively, which met the requirement that the relative standard deviation of the copper content of parallel samples was within 10%. The relative deviations of the method provided in Comparative Example 2 (without adding a masking agent) relative to the ICP method were 34.13%-18.24%-15.87%, which did not meet the requirement that the relative standard deviation of the copper content of parallel samples was within 10%. It can be seen that the composite masking agent has a more obvious effect on the test results.

[0171] In summary, the kit provided by the present invention solves the pain points of traditional copper ion detection methods in salt water matrices through four-dimensional optimization of "sensitivity-anti-interference-convenience-environmental protection", becoming an ideal tool for rapid analysis of copper ions in high-salt environments; in addition, the determination method provided by the present invention does not require large-scale instruments and equipment and professional personnel to operate, is easy to operate, can cope with sudden environmental pollution incidents or large-scale quality screening and detection, and promotes the standardization and popularization of on-site detection technology.

[0172] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A kit for determining the copper ion concentration in salt water, characterized in that: The kit includes a masking reagent, a color developing reagent, a standard volume fixing reagent, and a diluting reagent; The masking reagent includes a buffer solution, a reducing agent and a masking agent; the color developing reagent includes a color developing agent and an organic solvent; the standard constant volume reagent contains Cu 2+ The content is 0; the salinity of the dilution reagent is the same as that of the brine.

2. The test kit for measuring copper ion concentration in salt water according to claim 1, wherein The pH value of the masking agent is 4 to 6; Preferably, the masking agent comprises Cl - Masking agents and metal ion masking agents; Preferably, in terms of mass fraction, the masking agent comprises: Cl - 0.45-0.55 wt% of a masking agent, 0.08-0.12 wt% of a metal ion masking agent, 4.5-5.5 wt% of a reducing agent, and the remainder being a buffer solution; Preferably, the buffer solution comprises acetic acid-sodium acetate solution; Preferably, the concentration of the acetic acid-sodium acetate solution is 0.45 to 0.55 mol / L; Preferably, the Cl - The masking agent includes thiourea and / or potassium thiocyanate, preferably thiourea; Preferably, the metal ion masking agent comprises any one or a combination of at least two of EDTA, ammonium citrate, ascorbic acid or potassium sodium tartrate, preferably EDTA; Preferably, the reducing agent comprises hydroxylamine hydrochloride.

3. The test kit for measuring copper ion concentration in salt water according to claim 1 or 2, wherein The developer comprises any one of dithizone, diphenylcarbazide or neocuproine or a combination of at least two thereof, preferably neocuproine; Preferably, the organic solvent comprises an ethanol solution; Preferably, the content of the developer in the color developing reagent is 0.1 to 0.2 wt%; Preferably, the content of the ethanol solution in the color developing reagent is 48-52 wt%.

4. The kit for measuring the copper ion concentration in salt water according to any one of claims 1 to 3, wherein Cu removal 2 + In addition, the composition of the standard volume-fixing reagent is the same as that of the saline to be tested; Preferably, Cl in the dilution reagent - and SO4 2- The content is the same as that of the brine to be tested.

5. A method for determining the copper ion concentration in salt water, characterized in that: The determination method is carried out using the kit for determining the copper ion concentration in salt water according to any one of claims 1 to 4.

6. The measuring method according to claim 5, characterized in that The measuring method comprises the following steps: (1) Prepare several standard solutions using standard volume reagents, then sequentially mix the masking reagent and the colorimetric reagent, and determine the absorbance before establishing the Cu concentration of the standard solution. 2+ Concentration-absorbance relationship curve; (2) diluting the saline solution to be tested with a diluting reagent to obtain a mixed solution, and then sequentially mixing a masking reagent and a color developing reagent to obtain a mixed solution to be tested; (3) The absorbance of the mixed solution to be tested is measured to obtain the absorbance A0 of the mixed solution to be tested, and the absorbance A0 is substituted into the Cu obtained in step (1). 2+ In the concentration-absorbance relationship curve, the Cu 2+ concentration.

7. The measuring method according to claim 6, wherein The preparation method of the standard solution in step (1) comprises: adding A mL, B mL, C mL, D mL, E mL, and F mL of a 1000 mg / L copper standard working solution to a volumetric flask, respectively, and then using a standard volume-fixing reagent to adjust the volume to the standard mark of the volumetric flask to obtain a standard solution; wherein A < B < C < D < E < F, and A = 0; Preferably, the volume ratio of the masking reagent, color developing reagent and standard solution in step (1) is 4-6:0.8-1.2:10; Preferably, the Cu of the standard solution in step (1) 2+ The linear relationship of the concentration-absorbance curve is: A=mc(Cu 2+ )+n, where m and n are constants, A is the absorbance, c(Cu 2+ ) is the copper ion concentration.

8. The measuring method according to claim 6 or 7, characterized in that In step (2), when the Cu 2+ When the concentration is 0.5-10 mg / L, no dilution is performed; Preferably, when the Cu 2+ When the concentration is 10-100 mg / L, the dilution multiple of the dilution treatment is 5-10 times; Preferably, when the Cu 2+ When the concentration is greater than 100 mg / L, the dilution multiple of the dilution treatment is 15 to 25 times; Preferably, the volume ratio of the masking reagent, the color developing reagent and the mixed solution in step (2) is 4-6:0.8-1.2:

10.

9. The assay method according to any one of claims 6 to 8, characterized in that After mixing the masking reagents in step (1) and step (2), shake well and let stand for 1.5 to 2.5 minutes; Preferably, after mixing the color developing reagents in step (1) and step (2), shake well and let stand for 7 to 15 minutes.

10. The determination method according to any one of claims 6 to 9, characterized in that The wavelength used for the absorbance determination obtained in step (1) and step (3) is 400 to 500 nm; Preferably, the salt water Cu 2+ The concentration is calculated as follows: c(Cu 2+ , saline) = dilution factor × (A0-n) ÷ m.

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