A kit and method for determining the concentration of copper ions in brine

Abstract

The application provides a kit and a method for determining the concentration of copper ions in brine. The kit comprises a masking reagent, a chromogenic reagent, a standard dilution reagent, and a dilution reagent; the masking reagent comprises a buffer solution, a reducing agent and a masking agent; the chromogenic reagent comprises a chromogenic agent and an organic solvent; the standard dilution reagent contains Cu 2+ The content is 0; the salinity of the dilution reagent is the same as that of the brine. The kit provided by the application solves the pain points of traditional copper ion detection methods in the brine matrix through four-dimensional optimization of sensitivity, anti-interference, convenience and environmental protection, and becomes an ideal tool for rapid analysis of copper ions in a high-salt environment. In addition, the determination method provided by the application does not require large-scale instruments and equipment and professional operation, is simple to operate, can cope with sudden environmental pollution events or large-scale quality screening and detection, and promotes the standardization and popularization of on-site detection technology.

Description

Technical Field

[0001] This invention belongs to the field of water quality testing technology, and relates to a reagent kit and method for determining the concentration of copper ions in saline. Background Technology

[0002] In chemical production processes, brine is often used as a raw material, cooling medium, or reaction medium. 2+ The presence of Cu can have various impacts on brine quality, production processes, and final products, leading to equipment corrosion. 2+ Cu has oxidizing properties and readily forms micro-batteries with metals in brine, accelerating pitting or crevice corrosion of metal equipment. It also leads to a decrease in brine purity; during brine electrolysis, Cu... 2+ It will generate elemental copper during cathode reduction, contaminating caustic soda and chlorine products. 2+ It may adsorb onto the surface of salt crystals, causing abnormal color or substandard purity in industrial salt products. 2+ In brine, oxidation or decomposition reactions may occur, affecting the stability of the electrolysis process.

[0003] Colorimetric methods typically rely on the absorption spectrum of compounds formed by specific chemical reactions at specific wavelengths. The concentration of copper ions can be determined by measuring the absorbance at that wavelength. When determining copper ions colorimetrically, it is first necessary to select a suitable colorimetric reagent. Commonly used reagents include dithizone and diphenylcarbazide. These reagents react with copper ions to form compounds of a specific color. In the experiment, the color of the resulting compound can be optimized by adjusting the concentration of the colorimetric reagent and the reaction conditions. Colorimetric determination of copper ions has advantages such as simplicity, low cost, and accurate results. However, this method also has certain limitations. For example, the selection of the colorimetric reagent and the optimization of the 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 atomic emission spectrometry (ICP) provide accurate and reliable results, they require large-scale instruments and professional personnel, are time-consuming, expensive, and have limitations in terms of time and location, making them unsuitable for sudden environmental pollution events 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 test strip and its application. The method uses PE-NC copper ion test strip prepared by loading phycoerythrin onto a nitrocellulose membrane. The synthesis method is simple and relatively low-cost. This test strip only requires training operators to use a small portable spectrophotometer for measurement. Phycoerythrin exhibits high specificity for copper ions after successful loading onto the nitrocellulose membrane; specificity testing revealed that other metal ions cannot produce significant color differences. However, this method does not consider the interference from high concentrations of chloride ions and other salts, as well as pH values, in saline solutions. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a kit and method for determining the concentration of copper ions in saline solution. The kit can test the concentration of copper ions in saline solution and has the advantages of high testing efficiency and high accuracy.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] This invention provides a kit for determining the concentration of copper ions in saline solution, the kit comprising a masking reagent, a colorimetric reagent, a standard volume-fixing reagent, and a dilution reagent;

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

[0010] The kit provided by this invention allows for the rapid and accurate determination of copper ion concentration in saline solution; wherein the masking reagent is used to mask Cl in the saline solution being tested. - SO4 2- Ca 2+ Mg 2+ Fe 3+ 、Sr 2+ Ba 2+ Interfering ions; the colorimetric reagent can combine with cuprous ions to form a colorimetric complex; the standard volume-fixing reagent is used to prepare the standard solution for the working curve to avoid matrix effects; and provides a standard working curve to provide data support for the subsequent calculation of copper ion content in the saline solution to be tested; the dilution reagent is used to dilute the high concentration of the saline solution to ensure that the chloride and sulfate ion strengths in the saline solution remain basically unchanged, and further determine the accuracy of the copper ion concentration calculation;

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

[0012] In this 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] Wherein, Ca 2+ The concentration is 0.8–3.0 mg / L, for example, it can be 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 range are also applicable.

[0014] The Mg 2+ The concentration is 0.1 to 0.5 mg / L, for example, it can be 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 range are also applicable.

[0015] The Fe 3+ The concentration is 0.1 to 0.5 mg / L, for example, it can be 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 range are also applicable.

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

[0017] The Sr 2+ The concentration is 0.1 to 0.5 mg / L, for example, it can be 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 range are also applicable.

[0018] The Ba 2+The concentration is 0.5–1.0 mg / L, for example, it can be 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 range are also applicable.

[0019] The Cl - The concentration is 290–320 g / L, for example, it can be 290 g / L, 300 g / L, 310 g / L or 320 g / L, but is not limited to the listed values. Other values ​​not listed within the range are also applicable.

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

[0021] As a preferred embodiment 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, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

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

[0023] Preferably, the masking agent comprises, by mass fraction: 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 a buffer solution.

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

[0025] The content of metal ion masking agent in the masking reagent is 0.08 to 0.12 wt%, for example, it can be 0.08 wt%, 0.09 wt%, 0.1 wt%, or 0.12 wt%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] The reducing agent content in the masking reagent is 4.5 to 5.5 wt%, for example, it can be 4.5 wt%, 4.8 wt%, 5.1 wt%, or 5.5 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] Preferably, the buffer solution comprises an 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, it can be 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. Other values ​​within the range that are not listed are also applicable.

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

[0030] In this invention, chloride ions in salt water readily react with Cu in a high-salt environment. + The formation of CuCl2 complexes reduces colorimetric efficiency. This invention utilizes Cl... - Masking agents are preferentially associated with Cu + Bind, block Cl - To reduce interference and further improve color development 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, with EDTA being preferred.

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

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

[0034] As a preferred embodiment of the present invention, the colorimetric agent comprises any one or a combination of at least two of dithizone, diphenylcarbazide, or neo-cuprane. Typical but non-limiting combinations include: a combination of dithizone and diphenylcarbazide, a combination of dithizone and neo-cuprane, a combination of diphenylcarbazide and neo-cuprane, or a combination of dithizone, diphenylcarbazide, and neo-cuprane, preferably neo-cuprane.

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

[0036] Preferably, the content of the colorimetric reagent in the colorimetric reagent is 0.1 to 0.2 wt%, for example, it can be 0.1 wt%, 0.14 wt%, 0.17 wt%, or 0.2 wt%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

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

[0038] In this invention, if the concentration of the colorimetric reagent is too low, the color development will be incomplete, resulting in insufficient sensitivity; if the concentration is too high, the background absorbance will increase. In addition, the ethanol solution content is controlled to avoid excessive evaporation or insufficient dissolution.

[0039] In this invention, both the masking reagent and the colorimetric reagent are stored in brown bottles away from light.

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

[0041] Preferably, the diluting reagent contains Cl - and SO4 2- The content of [something] is the same as that of the saline solution to be tested.

[0042] Secondly, the present invention provides a method for determining the concentration of copper ions in saline solution, wherein the method uses the reagent kit for determining the concentration of copper ions in saline solution provided in the first aspect.

[0043] As a preferred embodiment of the present invention, the measurement method provided in the second aspect of the present invention includes the following steps:

[0044] (1) Prepare several standard solutions using standard dilution reagents, then mix masking reagents and colorimetric reagents sequentially, and determine the absorbance to establish the Cu content of the standard solutions. 2+ Concentration-absorbance curve;

[0045] (2) The saline solution to be tested is diluted with a diluting reagent to obtain a mixed solution, and then the masking reagent and the colorimetric reagent are mixed in sequence to obtain the mixed solution to be tested;

[0046] (3) Measure the absorbance of the mixture to be tested to obtain the absorbance A0, and substitute the absorbance A0 into the Cu obtained in step (1). 2+ From the concentration-absorbance curve, the Cu of the saline solution to be tested is obtained. 2+ concentration.

[0047] Preferably, the method for preparing the standard solution in step (1) includes: adding AmL, BmL, CmL, DmL, EmL, and FmL of 1000mg / L copper standard working solution to volumetric flasks respectively, and then using a standard volumetric reagent to dilute to the standard mark of the volumetric flasks to obtain the standard solution; wherein, A < B < C < D < E < F, and A = 0.

[0048] Preferably, the volume ratio of the masking reagent, colorimetric reagent and standard solution in step (1) is 4-6:0.8-1.2:10, 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 unlisted values ​​within the range are also applicable.

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

[0050] Preferably, in step (2), when the Cu in the saline solution to be tested... 2+ No dilution is required when the concentration is 0.5–10 mg / L;

[0051] Preferably, when Cu in the saline solution to be tested 2+ When the concentration is 10 to 100 mg / L, the dilution factor for 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, etc., but is not limited to the listed values. Other values ​​not listed within the value range are also applicable.

[0052] Preferably, when Cu in the saline solution to be tested 2+ When the concentration is greater than 100 mg / L, the dilution factor for the dilution treatment is 15 to 25 times, for example, it can be 15 times, 17 times, 19 times or 25 times, but it is not limited to the listed values. Other values ​​not listed within the value range are also applicable.

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

[0054] Preferably, after mixing the masking reagent in steps (1) and (2), the mixture is shaken and allowed to stand for 1.5 to 2.5 minutes, for example, 1.5 minutes, 1.7 minutes, 1.9 minutes, 2.1 minutes, 2.3 minutes or 2.5 minutes, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0055] Preferably, after mixing the colorimetric reagent in steps (1) and (2), the mixture is shaken well and allowed to stand for 7 to 15 minutes, for example, 7 minutes, 8 minutes, 9 minutes, 14 minutes or 15 minutes, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0056] Preferably, the wavelength used for absorbance measurement in steps (1) and (3) is 400-500 nm, for example, it can be 400 nm, 420 nm, 440 nm, 460 nm, 480 nm or 500 nm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0057] Preferably, the saline solution Cu to be tested in step (3) 2+ The formula for calculating concentration is:

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

[0059] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all 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 concentration of copper ions in saline provided by the present invention can realize the rapid determination of the concentration of copper ions in saline.

[0062] (2) This invention, through the aforementioned kit for determining the concentration of copper ions in saline solution, addresses the pain points of traditional copper ion detection methods in saline matrixes, such as Cl, through four-dimensional optimization of "sensitivity, anti-interference, convenience, and environmental friendliness." - 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) This invention does not require large instruments and equipment or professional personnel to operate, such as traditional atomic absorption spectrometry or ICP-MS. It is easy to operate and can cope with sudden environmental pollution events or large-scale quality screening and detection, thus promoting the standardization and popularization of on-site detection technology.

[0064] (4) Cu in the standard solution established in this invention 2+ R of the concentration-absorbance curve 2 All values ​​were above 0.999, indicating that the determination of copper ion concentration in saline solution showed good linear correlation under this analytical method, meeting the control requirements in GB / T27404-2008 "Laboratory Quality Control Standard for Food Physicochemical Testing". The measurement results are accurate and can be used for routine testing. Attached Figure Description

[0065] Figure 1 Cu in the standard solution provided in Example 1 of the present invention 2+ Concentration-absorbance relationship curve. Detailed Implementation

[0066] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

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

[0068] Example 1

[0069] This embodiment provides a kit for determining the concentration of copper ions in saline solution. The kit includes a masking reagent, a colorimetric reagent, a standard volume-fixing reagent, and a dilution reagent.

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

[0071] The masking agent has a pH of 5; the masking agent includes Cl. - Masking agents and metal ion masking agents; the masking agents, by mass fraction, comprise: Cl - Masking agent 0.5 wt%, metal ion masking agent 0.1 wt%, reducing agent 5 wt%, balance is buffer solution;

[0072] The buffer solution comprises an 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 colorimetric reagent is neocopperamine; the organic solvent is an ethanol solution; the content of the colorimetric reagent in the colorimetric reagent is 0.1 wt%; the content of the ethanol solution in the colorimetric reagent is 50 wt%.

[0074] Example 2

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

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

[0077] Example 3

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

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

[0080] Example 4

[0081] This embodiment provides a kit for determining the concentration of copper ions in saline solution. The only difference between this kit and that in Example 1 is:

[0082] This embodiment omits the reducing agent in the masking reagent.

[0083] Comparative Example 1

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

[0085] This comparative example omits the masking agent and buffer solution in the masking reagent.

[0086] Application Example 1

[0087] This application example provides a method for determining the concentration of copper ions in saline solution, wherein the method is performed using the kit for determining the concentration of copper ions in saline solution described in Example 1.

[0088] This application example measures the copper ion content of three saline solutions: saline A has a copper ion content ranging from 10 to 100 mg / L, saline B has a copper ion content ranging from 0.5 to 10 mg / L, and saline C has a copper ion content ranging from 100 to 600 mg / L.

[0089] The determination method includes the following steps:

[0090] (1) Prepare standard solutions with concentration gradients of 0, 2, 5, 10, 20, 30, and 40 mg / L using standard dilution reagents, and establish the Cu content of the standard solutions. 2+ Concentration-absorbance curve (e.g.) Figure 1 (As shown), the specific steps are as follows:

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

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

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

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

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

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

[0097] g. 30mg / L standard solution: Pipette 3.0mL of copper standard working solution (1000mg / L) into a 100mL volumetric flask, dilute to the mark with standard dilution reagent and mix well to make standard solution #5;

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

[0099] Then, take 10 mL of the above standard solutions 0#, 1#, 2#, 3#, 4#, 5#, and 6# respectively and add them to a 50 mL colorimetric tube. 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, the zero point was adjusted with pure water, and the absorbance of standard solutions 0#, 1#, 2#, 3#, 4#, 5#, and 6# was measured at 450 nm using a 1 cm cuvette, as shown in Table 1.

[0101] Table 1

[0102]

[0103]

[0104] Finally, the concentration of copper ions in the brine was plotted on the x-axis (mg / L) and absorbance on the y-axis (ABS), and the corresponding working curve A = 0.0054c (Cu) was plotted. 2+ +0.008, R 2 =0.9994, such as Figure 1 As shown.

[0105] (2) The saline solution to be tested is diluted with a dilution reagent to obtain a mixed solution. Then, the masking reagent and the colorimetric reagent are mixed in sequence to obtain the mixed solution to be tested. The specific steps are as follows:

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

[0107] The method for preparing the spiked saline solution includes:

[0108] Sample A1#: Accurately transfer 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 mix 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) into a 100 mL volumetric flask, dilute to the mark with A0# copper saline solution, and mix well. The theoretical copper content of this solution should be (A0# sample value + 20) mg / L;

[0110] Sample B1#: Accurately transfer 1.00 mL of copper standard working solution (1000 mg / L) into a 100 mL volumetric flask, dilute to the mark with B0# copper saline solution, and mix well. The theoretical copper content of this solution should be (B0# sample value + 10) mg / L;

[0111] Sample B2#: Accurately transfer 2.00 mL of copper standard working solution (1000 mg / L) into a 100 mL volumetric flask, dilute to the mark with B0# copper saline solution, and mix well. The theoretical copper content of this solution should be (B0# sample value + 20) mg / L;

[0112] C1# Sample: Accurately transfer 10.00 mL of copper standard working solution (1000 mg / L) into a 100 mL volumetric flask, dilute to the mark with C0# copper saline sample, and mix well. The theoretical copper content of this solution should be (C0# sample value + 100) mg / L;

[0113] C2# Sample: Accurately transfer 20.00 mL of copper standard working solution (1000 mg / L) into a 100 mL volumetric flask, dilute to the mark with C0# copper saline solution, and mix well. The theoretical copper content of this solution should be (C0# sample value + 200) mg / L.

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

[0115] a. For samples A0#, A1#, and A2#: Add 10 mL of sample to a colorimetric tube, add 5 mL of masking reagent, shake well, and let stand for 2 minutes to reduce Cu. 2+ Cu + At the same time, to mask the interference, add 1 mL of colorimetric 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#: Add 1 mL of sample and 9 mL of diluent to a colorimetric tube, add 5 mL of masking reagent, shake well, and let stand for 2 minutes to reduce Cu. 2+ Cu + At the same time, it masks interference; then add 1 mL of colorimetric reagent, shake well and let stand at room temperature for 8 minutes, the solution turns orange-yellow;

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

[0118] (3) Measure the absorbance of the mixture to be tested to obtain the absorbance A0, and substitute the absorbance A0 into the Cu obtained in step (1). 2+ From the concentration-absorbance curve, the Cu of the saline solution to be tested is obtained. 2+ The concentrations are calculated using the formulas shown below, and the sample detection data are shown in Table 2.

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

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

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

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

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

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

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

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

[0127] Sample C2#: 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 meet the quality control requirement that the absolute value of the difference between two independent test results obtained under repeated conditions does not exceed 10% of the arithmetic mean; the coefficients of variation of the test results all meet the control requirement of ≤3.8%.

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

[0133] Table 3

[0134]

[0135] As shown in Table 3, the method provided by this invention can meet the quality control requirements of spiked recovery rate within 95% to 105%.

[0136] Application Example 2-4

[0137] Application Examples 2-4 provide a method for determining the concentration of copper ions in saline solution, wherein the determination method is performed using the kit for determining the concentration of copper ions in saline solution provided in Examples 2-4.

[0138] Compared to Application Example 1, in Application Example 2, the lower concentration of the colorimetric reagent leads to sensitivity and linearity failure, resulting in a larger deviation between the calculated copper ion concentration and the actual concentration; in Application Example 3, when the pH value of the masking reagent is too high, Cl... - The masking agent's binding affinity to cuprous ions drops sharply, Cl - Interference intensifies; the reducing power of the reducing agent decreases at pH > 6, and ferric ions cannot be fully reduced, competing to consume the reducing agent and oxidizing cuprous ions, 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, so a standard working curve cannot be obtained, and the concentration of copper ions in the saline solution 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 saline solution, wherein the method uses the kit for determining the concentration of copper ions in saline solution described in Comparative Example 1.

[0141] The saline solution to be tested and the determination method in this comparative application example are the same as those in application example 1. The results of the determination of copper ions in the sample are shown in Table 4.

[0142] Table 4

[0143]

[0144]

[0145] As shown in Table 4, the relative range of copper ion concentration in saline obtained by using the kit provided in Comparative Example 1 does not meet the quality control requirement that the absolute value of the difference between two independent measurements 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 spiking recovery rate of the 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] As shown in Table 5, the spiked recovery rate 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 saline using the ICP method.

[0152] The instruments used in the ICP method include: plasma emission spectrometer: ICAP6300, analysis software: ITEVA, and sample introduction system: EMT sample introduction 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, atomizer working pressure: 0.2 MPa, vertical observation height: 12 mm, wavelength: 324.7 nm.

[0155] Methods for determining copper ions in saline solution include:

[0156] The method for determining the copper ion content in saline solution A using ICP includes the following steps:

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

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

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

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

[0161] II. The method for determining the copper ion content in saline solutions B and C using ICP includes the following steps:

[0162] Prepare five 50mL volumetric flasks, K0, K1, K2, K3, and K4. Transfer 0mL, 1mL, 2mL, 3mL, and 4mL of copper standard solution (1000mg / L) to each flask, respectively. Dilute to the mark with ultrapure water, shake well, and determine the copper content in the saline solution using the standard curve method.

[0163] Copper saline sample: Accurately transfer 5.00 mL of copper standard stock solution (1 mg / L) into a 100 mL volumetric flask, dilute to the mark with copper saline sample, and mix well. The theoretical copper content of this solution should be (sample value + 50) ug / L.

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

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

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

[0167] Table 6

[0168]

[0169] A comprehensive analysis of Tables 2-6 shows that, using the kit and assay method provided by this invention, the relative range meets the quality control requirement that the absolute value of the difference between two independent assay results obtained under repeated conditions does not exceed 10% of the arithmetic mean; the coefficient of variation meets the control requirement of ≤3.8%; and the spiked recovery rate also meets the quality control requirement of 95%–105%. Therefore, the kit and assay method provided by this invention meet the control requirements for test methods in the national standard GB / T 27404-2008 "Laboratory Quality Control Standard for Physicochemical Testing of Food".

[0170] Meanwhile, when analyzing the copper content in saline using the kit provided by this invention and using the ICP method, under the same analytical conditions and with the same equipment, the relative deviations of the method provided by this invention compared to the ICP method were 4.55%, 3.16%, and 1.27%, respectively, satisfying that the relative standard deviations of copper content determination for parallel samples were all within 10%. The relative deviations of the method provided in Comparative Example 2 (without masking agent) compared to the ICP method were 34.13%-18.24%-15.87%, failing to satisfy that the relative standard deviations of copper content determination for parallel samples were all within 10%. It can be seen that the composite masking agent has a more significant effect on the test results.

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

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

Claims

1. A kit for determining the concentration of copper ions in saline solution, characterized in that, The kit includes a masking reagent, a colorimetric reagent, a standard volume-fixing reagent, and a dilution reagent; The masking reagent includes a buffer solution, a reducing agent, and a masking agent; the colorimetric reagent includes a colorimetric agent and an organic solvent; the standard volume-adjusting reagent contains Cu. 2+ The content is 0; the salinity of the diluting reagent is the same as that of the saline solution; The masking reagent has a pH value of 4-6; The masking reagent comprises, by mass fraction: Cl - Masking agent 0.45~0.55wt%, metal ion masking agent 0.08~0.12wt%, reducing agent 4.5~5.5wt%, balance is buffer solution; The buffer solution includes an acetic acid-sodium acetate solution; The concentration of the acetic acid-sodium acetate solution is 0.45~0.55 mol / L; The Cl - The masking agent is thiourea; The metal ion masking agent is EDTA; The reducing agent includes hydroxylamine hydrochloride.

2. The kit for determining the concentration of copper ions in saline solution according to claim 1, characterized in that, The colorimetric agent includes any one or a combination of at least two of dithizone, diphenylcarbazide, or neo-copper hydroxide.

3. The kit for determining the concentration of copper ions in saline solution according to claim 2, characterized in that, The color developer is neocopperamine.

4. The kit for determining the concentration of copper ions in saline solution according to claim 1, characterized in that, The organic solvent includes an ethanol solution.

5. The kit for determining the concentration of copper ions in saline solution according to claim 1, characterized in that, The content of the colorimetric reagent in the colorimetric reagent is 0.1~0.2wt%.

6. The kit for determining the concentration of copper ions in saline solution according to claim 4, characterized in that, The ethanol solution in the colorimetric reagent contains 48-52 wt%.

7. The kit for determining the concentration of copper ions in saline solution according to claim 1, characterized in that, Except Cu 2+ In addition, the composition of the standard dilution reagent is the same as that of the saline solution to be tested.

8. The kit for determining the concentration of copper ions in saline solution according to claim 1, characterized in that, The colorimetric reagent, the diluting reagent, Cl - and SO4 2- The content of [something] is the same as that of the saline solution to be tested.

9. A method for determining the concentration of copper ions in saline solution, characterized in that, The determination method is performed using the kit for determining the concentration of copper ions in saline solution as described in any one of claims 1-8.

10. The determination method according to claim 9, characterized in that, The determination method includes the following steps: (1) Prepare several standard solutions using standard dilution reagents, then mix masking reagents and colorimetric reagents sequentially, and determine the absorbance to establish the Cu content of the standard solutions. 2+ Concentration-absorbance curve; (2) The saline solution to be tested is diluted with a diluent to obtain a mixed solution, and then the masking reagent and the colorimetric reagent are mixed in sequence to obtain the mixed solution to be tested; (3) Measure the absorbance of the mixture to be tested to obtain the absorbance A0 of the mixture to be tested, and substitute the absorbance A0 into the Cu obtained in step (1). 2+ From the concentration-absorbance curve, the Cu of the saline solution to be tested is obtained. 2+ concentration.

11. The determination method according to claim 10, characterized in that, The method for preparing the standard solution in step (1) includes: adding AmL, BmL, CmL, DmL, EmL, and FmL of 1000mg / L copper standard working solution to volumetric flasks respectively, and then using standard volume-diluting reagent to dilute to the standard mark of the volumetric flasks to obtain the standard solution; wherein, A<B<C<D<E<F, and A=0.

12. The determination method according to claim 10, characterized in that, The volume ratio of the masking reagent, colorimetric reagent and standard solution in step (1) is 4~6:0.8~1.2:

10.

13. The determination method according to claim 10, characterized in that, Step (1) Cu of the standard solution 2+ The linear relationship between concentration and absorbance is: A = mc(Cu) 2+ )+n, where m and n are constants, A is absorbance, and c(Cu) 2+ () represents the copper ion concentration.

14. The determination method according to claim 10, characterized in that, In step (2), when the Cu in the saline solution to be tested... 2 + No dilution is required when the concentration is 0.5~10 mg / L.

15. The determination method according to claim 10, characterized in that, When Cu in the saline solution to be tested 2+ When the concentration is 10~100mg / L, the dilution factor for the dilution treatment is 5~10 times.

16. The determination method according to claim 10, characterized in that, When Cu in the saline solution to be tested 2+ When the concentration is >100 mg / L, the dilution factor for the dilution treatment is 15 to 25 times.

17. The determination method according to claim 10, characterized in that, The volume ratio of the masking reagent, colorimetric reagent and mixture in step (2) is 4~6:0.8~1.2:

10.

18. The determination method according to claim 10, characterized in that, After mixing the masking reagent in steps (1) and (2), shake well and let stand for 1.5 to 2.5 minutes.

19. The determination method according to claim 10, characterized in that, After mixing the colorimetric reagents in steps (1) and (2), shake well and let stand for 7-15 minutes.

20. The determination method according to claim 10, characterized in that, Steps (1) and (3) yield the wavelength of 400~500nm used for absorbance measurement.

21. The determination method according to claim 10, characterized in that, Step (3) The saline solution Cu to be tested 2+ The formula for calculating concentration is: c(Cu 2+ (salt water) = dilution factor × (A0-n) ÷ m.

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