A method for determining the quality and purity of silver in a ceramic cup with a silver layer on the inner wall.

Abstract

This invention provides a method for determining the mass and purity of silver in ceramic cups with a silver layer on the inner wall, belonging to the field of precious metal analysis and detection technology. Addressing the technical problems of existing physical methods being unable to remove the silver layer and chemical methods being affected by bismuth interference from the ceramic matrix in purity determination, this invention uses silver-free ceramic cups from the same batch as a specific blank control. The silver-layered sample and the blank sample are simultaneously digested using an optimized ratio of nitric acid solution under specific temperature and time conditions. The mass of silver is accurately determined by ammonium thiocyanate titration, and the impurity concentrations in the sample and blank solutions are determined separately by spectroscopic methods. Background interference such as bismuth dissolved from the ceramic is accurately subtracted using a difference method, and the silver purity is finally calculated through normalization. This method enables continuous and accurate determination of silver mass and purity with a single sample dissolution, effectively solving the problem of interference from complex matrices, significantly improving the precision and accuracy of detection, and providing a feasible technical solution for the quality inspection of silver-layered ceramic products.

Description

Technical Field

[0001] This invention relates to the field of precious metal analysis and detection technology, specifically to a method for determining the quality and purity of silver in a ceramic cup with a silver layer on its inner wall. Background Technology

[0002] Silver-plated ceramic cups are typically made from 99.9% pure silver powder. The process involves slurry preparation, inner wall coating, natural air drying, high-temperature firing, hand polishing, and a second silvering process, ensuring the silver layer adheres firmly to the ceramic inner wall, creating a delicate and smooth silvered texture. These products combine the excellent heat retention and tactile feel of ceramics with the high-end visual effect of the silver plating. They are often used as gifts and in high-end home settings, making them practical collectibles that combine practicality, cultural connotation, and artistic value. Bismuth, a key pigment and additive in ceramic production, can significantly improve the gloss and chemical stability of ceramic glazes, optimize ceramic density, hardness, and high-temperature resistance, while lowering the sintering temperature and simplifying the production process. Bismuth compounds can also improve the color uniformity and sintering performance of glazes, adjust glaze viscosity, and enhance glaze adhesion and wear resistance. Therefore, ceramic matrices usually contain a certain amount of bismuth, providing support for the aesthetics and durability of ceramic products.

[0003] As precious metal decorative products, ceramic cups with a silver layer on the inner wall require rigorous testing of the silver layer's quality and purity before they can be sold on the market, and a test report must be issued. Currently, the quality testing of precious metal jewelry is mostly based on QB / T 1690-2004 "Regulations on the Tolerances for Quality Measurement of Precious Metal Jewelry," while purity testing generally uses GB / T 18043-2013 "Determination of Precious Metal Content in Jewelry - X-ray Fluorescence Spectroscopy." However, QB / T 1690-2004 is only applicable to the quality determination of a homogeneous precious metal matrix and cannot be used to separately test the quality of the silver layer. While the X-ray fluorescence spectrometry method used in GB / T 18043-2013 has advantages such as being non-destructive and rapid, it is limited by the X-ray penetration depth (usually not exceeding 10 μm) and is only suitable for testing pure matrix precious metals with uniform composition, no coatings, and no sandwich structures. It is difficult to accurately characterize the purity of the silver layer in ceramic cups with a silver layer on the inner wall. Neither of these standards can meet the actual testing needs of this type of composite structure product, creating difficulties for quality control and market circulation.

[0004] In testing practice, the inner silver layer is tightly bonded to the ceramic substrate, making it difficult to completely peel off the silver layer using conventional physical methods, thus preventing direct weighing and purity analysis. While chemical reagents such as nitric acid can be used to dissolve the silver layer and separate it from the ceramic, the bismuth inherent in the ceramic substrate will simultaneously dissolve and enter the silver solution. Bismuth is a key impurity element monitored in silver purity testing. The inability to distinguish whether the bismuth source originates from the ceramic substrate or the silver layer itself directly interferes with the accurate quantification of bismuth impurities in the silver sample, ultimately leading to lower-than-expected silver purity results or a failure to meet standards. This severely impacts the quality evaluation, market transactions, and industry standardization of precious metal decorative ceramic products.

[0005] In view of this, it is necessary to study a method that can accurately determine the quality and purity of silver in ceramic cups with silver layers on the inner wall, solve technical problems such as the difficulty in separating the silver layer and interference from bismuth, and provide reliable technical support for the quality inspection and market circulation of such products, so as to solve the above-mentioned technical problems. Summary of the Invention

[0006] In view of the technical problems existing in the background art, this application provides a method for determining the quality and purity of silver in a ceramic cup with a silver layer on the inner wall, aiming to solve the problems such as the difficulty in separating the silver layer from the ceramic, the inability to accurately determine the quality of silver, and the interference of bismuth element in the determination of silver purity, so as to achieve accurate determination of the quality and purity of silver in a ceramic cup with a silver layer on the inner wall.

[0007] This invention provides a method for determining the quality and purity of silver in a ceramic cup with a silver layer on its inner wall, comprising the following steps:

[0008] S1, Dissolution of the sample to be tested: Place the ceramic cup containing the silver layer on the inner wall of the sample to be tested in an acid solution, control the dissolution temperature and dissolution time to dissolve the silver layer, cool and then make up to a final volume to obtain the sample solution;

[0009] S2, Sample blank control (blank experiment): Select a ceramic cup with no silver layer on the inner wall from the same batch and specifications as the ceramic cup to be tested, place it in the same acid solution of the same volume as in step S1, and treat it under the same dissolution temperature and dissolution time conditions. After cooling, make up the volume to obtain a blank solution.

[0010] S3, Silver mass determination: The mass of silver in the sample solution is determined by chemical titration, which is the mass of silver in the ceramic cup with a silver layer on the inner wall;

[0011] S4, Determination of impurity element concentration: The concentration of impurity elements in the sample solution and blank solution is determined by spectroscopic analysis. The actual concentration of impurity elements in silver is obtained by blank subtraction.

[0012] S5, Silver purity calculation: Based on the silver mass in step S3 and the actual concentration of impurity elements in step S4, the silver purity is calculated through normalization, which is the silver purity in the ceramic cup with a silver layer on the inner wall.

[0013] As a further improvement of the present invention, in steps S1 and S2, the acid solution is a nitric acid solution, which is prepared by measuring concentrated nitric acid and water at a volume ratio of 1:3 and mixing them evenly.

[0014] As a further improvement of the present invention, in steps S1 and S2, the dissolution temperature is 200~220℃, and the dissolution time is 5~7 minutes. The purpose of controlling the dissolution temperature and time is to ensure the dissolution of silver, which in turn ensures that the amount of bismuth leached from the ceramic is low and stable, thus solving the problem of large fluctuations in the bismuth concentration in the blank solution due to the high and unstable amount of bismuth leached.

[0015] As a further improvement of the present invention, in step S3, the chemical titration method is the ammonium thiocyanate titration method, using ferric ammonium sulfate as an indicator.

[0016] As a further improvement to the present invention, the specific process for silver mass determination in step S3 is as follows:

[0017] S31. Weigh out a predetermined mass of standard silver, dissolve it in an acid solution, add ferric ammonium sulfate indicator, titrate with ammonium thiocyanate standard solution to a pale red endpoint, record the volume consumed V1, and calculate the titer T.

[0018] S32, take a portion of the solution from the sample solution, add ferric ammonium sulfate indicator, titrate with ammonium thiocyanate standard solution to a light red endpoint, and record the volume consumed V2;

[0019] S33, Calculate the mass of silver: m Ag = T×V2×(V0 / V 分取 );

[0020] Where, m Ag V0 is the mass of silver in the ceramic cup containing a silver layer on the inner wall; V0 is the final volume of the sample solution .... 分取 V1 represents the volume of ammonium thiocyanate standard solution consumed by the standard silver solution at the titration endpoint; V2 represents the volume of ammonium thiocyanate standard solution consumed by the sample solution at the titration endpoint.

[0021] The formula for calculating the titer T of the ammonium thiocyanate standard solution is: T = (m1 × E) / V1;

[0022] Where m1 is the mass of standard silver weighed; E is the purity of the standard silver.

[0023] As a further improvement of the present invention, in step S4, the concentration of impurity elements is determined by inductively coupled plasma optical emission spectrometry (ICP-OES).

[0024] The impurity elements include at least one or more of the following: Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Pd, Sb, Se, Sn, Te, Ti, Zn, K, and Na.

[0025] As a further improvement of the present invention, the specific process for determining the impurity concentration in step S4 is as follows:

[0026] S41, Weigh a predetermined amount of pure silver and prepare a series of standard solutions containing a silver matrix, ensuring that the silver-containing standard solution medium is consistent with the sample solution medium. Use ICP-OES to determine the concentration C of impurity elements in the sample solution. i ;

[0027] S42, prepare a series of silver-free standard solutions, ensuring the medium of the silver-free standard solutions is consistent with that of the blank solution. The concentration of impurity elements (C) in the blank solution is determined using ICP-OES. b,i ;

[0028] S43, Calculate the actual concentration of impurity elements: C 实际 = C i - C b,i ;

[0029] Wherein, the impurity elements are, in order, Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Pd, Sb, Se, Sn, Te, Ti, Zn, K, and Na, and i is the i-th impurity element among the impurity elements.

[0030] As a further improvement of the present invention, the formula for normalizing the silver purity in step S5 is as follows:

[0031] ;

[0032] Where, ω Ag The purity of silver in a ceramic cup with a silver layer on its inner wall; C i This represents the concentration of impurity elements in the sample solution. C b , i This represents the concentration of impurity elements in the blank solution. ∑ ( C i -C b , i ) represents the sum of the concentrations of all impurity elements after deducting blanks.

[0033] As a further improvement of the present invention, the mass of pure silver weighed in step S41 is one-tenth of the mass of silver in the ceramic cup with a silver layer on the inner wall in step S33.

[0034] Beneficial effects:

[0035] 1. This invention solves the problem that the silver layer in ceramic cups cannot be peeled off, making it difficult to determine the quality of silver. It develops a method for titrating the quality of silver with ammonium thiocyanate, combining the measured quality of pure silver with the quality of impurities in pure silver measured by ICP-OES, and normalizing to achieve accurate determination of silver purity.

[0036] 2. This invention employs the optimal volume fraction of nitric acid solution, the optimal volume of nitric acid, the optimal dissolution temperature, and the optimal dissolution time. Only by combining these optimal conditions can the amount of bismuth leached from the ceramic be guaranteed to be low and stable. This solves the problem that the high and unstable bismuth leaching leads to large fluctuations in the bismuth concentration in the blank solution, resulting in poor precision and low accuracy in silver purity determination results.

[0037] 3. This invention abandons the traditional reagent blank or full-process blank, and uses ceramic cups of the same batch, style and specification without silver layer on the inner wall to conduct blank experiments. This effectively solves the problem that the bismuth dissolved in the ceramic is not deducted, resulting in high bismuth impurity content in silver, and realizes accurate determination of bismuth impurity content in silver.

[0038] 4. The blank experiment used in this invention is conducted on ceramic cups in which metal elements are dissolved. This is different from traditional reagent blank and full-process blank experiments. The purpose is to solve the problem that the leaching of bismuth, an impurity element in the ceramic cup, affects the purity of silver.

[0039] 5. This invention first accurately titrates the mass of pure silver in the silver layer. The silver purity is calculated by normalizing the mass of pure silver and the mass of impurities. This achieves accurate and continuous determination of the mass and purity of silver in a single sample dissolution, and the analysis sequence is fixed and cannot be changed.

[0040] 6. This invention uses a standard solution containing a silver matrix to determine the mass of impurities in a silver solution and a standard solution without a silver matrix to determine the mass of impurities in a blank solution. This ensures that the medium of the standard solution is consistent with the medium of the test solution, solves the problem of interference of the silver matrix on the determination of impurity elements, and makes the test method more scientific and accurate.

[0041] 7. This invention uses ammonium thiocyanate to titrate the mass of silver in a ceramic cup. This method is accurate, and the dissolved bismuth does not interfere with the determination of the silver mass.

[0042] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0043] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0044] Figure 1 This is a process flow diagram of the method for determining the quality and purity of silver in a ceramic cup with a silver layer on the inner wall, provided in an embodiment of the present invention. Detailed Implementation

[0045] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0047] In the description of the embodiments of this invention, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this invention, "multiple" means two or more, unless otherwise explicitly defined.

[0048] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0049] In the description of the embodiments of this invention, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0050] In the description of the embodiments of the present invention, the term "multiple" refers to two or more (including two), similarly, "multiple groups" refers to two or more (including two groups), and "multiple pieces" refers to two or more (including two pieces).

[0051] In the description of the embodiments of the present invention, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0052] In the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0053] To address the technical problems of existing technologies failing to effectively separate the silver layer and the interference of bismuth in ceramics in silver purity determination, this invention provides a method for determining the mass and purity of silver in ceramic cups with a silver layer on the inner wall. It abandons traditional reagent blanks or full-process blanks, proposing to use a ceramic cup of the same production batch, style, and specifications as the sample to be tested, but without a silver layer on the inner wall, as a blank control. This effectively eliminates bismuth and other impurity elements dissolved from the ceramic matrix during nitric acid dissolution. A combined determination system of "titration for mass determination + ICP-OES for impurity determination + normalization calculation" is constructed, combining ammonium thiocyanate titration (for accurate determination of the absolute mass of silver) with ICP-OES spectroscopy (for determination of the concentration of multiple impurity elements), and calculating silver purity through a specific normalization formula. This achieves accurate determination of silver mass and precise deduction of background interference to obtain silver purity after a single sample dissolution, solving the problem that a single method cannot simultaneously and accurately determine mass and purity. This invention also establishes optimal digestion process parameters for suppressing bismuth dissolution, determining the optimal volume ratio of nitric acid solution (nitric acid:water = 1:3), optimal heating and dissolution temperature (200–220°C), and optimal time (5–7 min). This minimizes and stabilizes the dissolution of bismuth in the ceramic while ensuring complete dissolution of the silver layer, reducing fluctuations in blank values ​​and improving the precision and accuracy of the determination. Furthermore, a matrix-matched standard curve strategy is constructed. When determining impurity elements, a standard solution containing a silver matrix is ​​used to measure the sample solution, while a standard solution without a silver matrix is ​​used to measure the blank solution. This eliminates the interference of the silver matrix on the determination of impurity elements, ensures the consistency between the standard solution medium and the test solution medium, and improves the scientific rigor and accuracy of impurity detection.

[0054] Please refer to Figure 1 As shown, this invention provides a method for determining the quality and purity of silver in a ceramic cup with a silver layer on the inner wall, comprising the following steps:

[0055] S1, Dissolution of the sample to be tested: Place the ceramic cup with the silver layer on the inner wall into a 500 mL beaker, add 220-250 mL of nitric acid solution, heat on a heating plate at 200-220 ℃ for 5-7 min until all the silver is dissolved, remove the ceramic cup, wash the ceramic cup with water 3-5 times, cool to room temperature, transfer to a 500 mL volumetric flask with water, mix well, record the solution as A1, and record the volume as V0;

[0056] S2, Sample blank control (blank experiment): Place a ceramic cup without a silver layer on the inner wall into a 500 mL beaker, add 220-250 mL of nitric acid solution, heat on a heating plate at 200-220 ℃ for 5-7 min until all the silver is dissolved, remove the ceramic cup, wash the ceramic cup with water 3-5 times, cool to room temperature, transfer the solution to a 500 mL volumetric flask, mix well, record the solution as A2, and record the volume as V0;

[0057] S3, Silver Mass Determination: The mass of silver in the sample solution is determined by chemical titration, which is the mass of silver in the ceramic cup with a silver layer on the inner wall; specifically including:

[0058] S31. Weigh 0.500 g of standard silver, accurate to 0.0001 g, and record the mass as m1. Place it in a 250 mL conical flask, add 10 mL of nitric acid solution, and heat it at a low temperature on an electric furnace until all the nitrogen oxides are dissolved and the yellow fumes disappear. Remove it and cool it to room temperature. Add 40 mL of deionized water and 1-2 mL of ferric ammonium sulfate solution. Add ammonium thiocyanate standard solution using a burette and titrate until the solution turns pale red, which is the titration endpoint. Record the volume of ammonium thiocyanate standard solution consumed as V1.

[0059] S32. Accurately transfer 50.00 mL of silver solution from solution A1 into a 250 mL conical flask, add 1-2 mL of ferric ammonium sulfate solution, add ammonium thiocyanate standard solution using a burette, and titrate until the solution turns pale pink as the titration endpoint. Record the volume of ammonium thiocyanate standard solution consumed as V2.

[0060] S33, Formula for calculating the mass of silver in a ceramic cup with a silver layer on the inner wall:

[0061] , ;

[0062] In the formula:

[0063] The titer of T-ammonium thiocyanate standard solution is expressed in grams per milliliter (g / mL).

[0064] m1—The mass of standard silver weighed, in grams (g).

[0065] E—Purity of standard silver;

[0066] V1 — The volume of ammonium thiocyanate standard solution consumed by the standard silver solution at the titration endpoint, expressed in milliliters (mL).

[0067] m Ag —The mass of silver in the ceramic cup with a silver layer on the inner wall, in grams (g);

[0068] V2—The volume of ammonium thiocyanate standard solution consumed by the sample solution at the titration endpoint, expressed in milliliters (mL).

[0069] 10 — Ratio of the final volume of the sample solution to the volume taken out.

[0070] S4, Impurity Element Concentration Determination: The concentration of impurity elements in the sample solution and blank solution is determined by spectroscopic analysis, and the actual concentration of impurity elements in silver is obtained by blank subtraction; specifically including:

[0071] S41. Weigh five pure silver samples (silver purity not less than 99.999%), with a mass of 0.200-0.500 g, and place them separately in polytetrafluoroethylene beakers. Add 5-10 mL of concentrated nitric acid to each sample and heat until completely dissolved. Transfer the silver solution to a 50 mL volumetric flask with water. Add 0 mL, 0.50 mL, 1.50 mL, 2.50 mL, and 5.00 mL of a mixed standard solution with a concentration of 100 ug / mL (containing Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Pd, Sb, Se, Sn, Te, Ti, Zn, K, and Na) to the mark with water and mix well. The prepared mixed standard solutions had concentrations of 0.00 ug / mL, 1.00 ug / mL, 3.00 ug / mL, 5.00 ug / mL, and 10.00 ug / mL, respectively. The concentrations of impurity elements in solution A1 were determined using an ICP-OES spectrometer and denoted as C. i ;

[0072] S42. Take five 50 mL volumetric flasks and add 5–10 mL of concentrated nitric acid to each. Then, add 0 mL, 0.50 mL, 1.50 mL, 2.50 mL, and 5.00 mL of a mixed standard solution with a concentration of 100 ug / mL (containing Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Pd, Sb, Se, Sn, Te, Ti, Zn, K, and Na) respectively. Dilute to the mark with water and mix well. The concentrations of the prepared mixed standard solutions are 0.00 ug / mL, 1.00 ug / mL, 3.00 ug / mL, 5.00 ug / mL, and 10.00 ug / mL, respectively. Measure the concentration of impurity elements in the A2 blank solution using an ICP-OES spectrometer and record it as C. b，i ;

[0073] S43, Calculate the actual concentration of impurity elements: C 实际 = C i - C b,i ;

[0074] S5, Silver purity calculation: Based on the silver mass in step S3 and the actual concentration of impurity elements in step S4, the silver purity is calculated by normalization, which is the silver purity in the ceramic cup with a silver layer on the inner wall.

[0075] Formula for calculating the purity of silver in a ceramic cup with a silver layer on the inner wall:

[0076] ;

[0077] In the formula:

[0078] ω Ag —Silver purity in ceramic cups with a silver layer on the inner wall, expressed in parts per thousand (‰).

[0079] m Ag —The mass of silver in the ceramic cup with a silver layer on the inner wall, in grams (g);

[0080] C i —The concentration of impurity elements in solution A1, expressed in micrograms per milliliter (ug / mL).

[0081] C b , i —The concentration of impurity elements in the A2 blank solution, in micrograms per milliliter (ug / mL).

[0082] ∑ ( C i -C b , i — The sum of the concentrations of all impurity elements after deducting the blank, expressed in micrograms per milliliter (ug / mL).

[0083] Preferably, in step S1, the nitric acid solution is prepared by measuring one volume of nitric acid and three volumes of deionized water, mixing them well, and preparing the solution immediately before use.

[0084] Preferably, in step S2, the production batch, style, and specifications of the ceramic cup without a silver layer on the inner wall are the same as those of the ceramic cup with a silver layer on the inner wall, the difference being that the inner wall of the ceramic cup does not contain silver.

[0085] Preferably, in step S3, the method for preparing the ferric ammonium sulfate solution is as follows: weigh 5.0 g of ferric ammonium sulfate, place it in a 250 mL beaker, add 30 mL of deionized water, add 5 mL of concentrated nitric acid, heat until the solid dissolves and the brown color disappears, cool to room temperature, dilute with deionized water to 50 mL, and mix well.

[0086] Preferably, in step S3, the preparation method of the ammonium thiocyanate standard solution is as follows: weigh 3.56 g of ammonium thiocyanate, place it in a 400 mL beaker, add 300 mL of deionized water to dissolve it, transfer it to a 500 mL volumetric flask with deionized water, dilute it to the mark with deionized water, mix well, and let it stand for 3 days.

[0087] Preferably, in step S3, the purity of the standard silver is 999.99‰ or higher.

[0088] Preferably, in step S4, the mass of pure silver weighed is one-tenth of the mass of silver in the ceramic cup with the silver layer on the inner wall in step five.

[0089] Preferably, in step S5, the silver in the ceramic cup with a silver layer on the inner wall consists of pure silver and silver impurities.

[0090] Example 1

[0091] Embodiment 1 of the present invention provides a method for determining the quality and purity of silver in a ceramic cup with a silver layer on the inner wall, comprising the following steps:

[0092] S1. Place the ceramic cup with the silver layer on its inner wall into a 500 mL beaker, add 220 mL of nitric acid solution, and heat on a 200 ℃ heating plate for 5 min until all the silver is dissolved. Remove the ceramic cup, wash it three times with water, cool it to room temperature, transfer it to a 500 mL volumetric flask, mix well, and record the solution as A1, with the volume as V0. In step S1, the nitric acid solution is prepared by measuring one volume of nitric acid and three volumes of deionized water, mixing well, and preparing fresh each time.

[0093] S2. Place a ceramic cup without a silver layer on the inner wall into a 500 mL beaker, add 220 mL of nitric acid solution, heat on a 200 ℃ heating plate for 5 min until all the silver is dissolved, remove the ceramic cup, wash the ceramic cup with water 3 times, cool to room temperature, transfer the solution to a 500 mL volumetric flask, mix well, and record the solution as A2 and the volume as V0.

[0094] S3, the mass of silver in the sample solution is determined by chemical titration, which is the mass of silver in the ceramic cup with a silver layer on the inner wall; including:

[0095] S31. Weigh 0.500 g of standard silver, accurate to 0.0001 g, and record the mass as m1. Place it in a 250 mL conical flask, add 10 mL of nitric acid solution, and heat it at a low temperature on an electric furnace until all the nitrogen oxides and yellow fumes disappear. Remove it and cool it to room temperature. Add 40 mL of deionized water and 1 mL of ferric ammonium sulfate solution. Add ammonium thiocyanate standard solution using a burette and titrate until the solution turns pale red, which is the titration endpoint. Record the volume of ammonium thiocyanate standard solution consumed as V1.

[0096] S32. Accurately transfer 50.00 mL of silver solution from solution A1 to a 250 mL conical flask, add 1 mL of ferric ammonium sulfate solution, and add ammonium thiocyanate standard solution using a burette. Titrate until the solution turns pale pink, which is the titration endpoint. Record the volume of ammonium thiocyanate standard solution consumed as V2.

[0097] S33, Formula for calculating the mass of silver in a ceramic cup with a silver layer on the inner wall:

[0098] ,

[0099] In the formula:

[0100] The titer of T-ammonium thiocyanate standard solution is expressed in grams per milliliter (g / mL).

[0101] m1—The mass of standard silver weighed, in grams (g).

[0102] E—Purity of standard silver;

[0103] V1 — The volume of ammonium thiocyanate standard solution consumed by the standard silver solution at the titration endpoint, expressed in milliliters (mL).

[0104] m Ag —The mass of silver in the ceramic cup with a silver layer on the inner wall, in grams (g);

[0105] V2—The volume of ammonium thiocyanate standard solution consumed by the sample solution at the titration endpoint, expressed in milliliters (mL).

[0106] 10 — Ratio of the final volume of the sample solution to the volume taken out.

[0107] S4, the concentrations of impurity elements in the sample solution and blank solution are determined by spectroscopic analysis, and the actual concentrations of impurity elements in silver are obtained by blank subtraction; including:

[0108] S41. Weigh five pure silver samples (silver purity not less than 99.999%), each weighing 0.2413 g. Place each sample in a polytetrafluoroethylene beaker and add 5 mL of concentrated nitric acid. Heat until completely dissolved. Transfer the silver solution to a 50 mL volumetric flask and add 0 mL, 0.50 mL, 1.50 mL, 2.50 mL, and 5.00 mL of a mixed standard solution with a concentration of 100 ug / mL (containing Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Pd, Sb, Se, Sn, Te, Ti, Zn, K, and Na) to the mark with water and mix well. The prepared mixed standard solutions had concentrations of 0.00 ug / mL, 1.00 ug / mL, 3.00 ug / mL, 5.00 ug / mL, and 10.00 ug / mL, respectively. The concentrations of impurity elements in solution A1 were determined using an ICP-OES spectrometer and denoted as C. i .

[0109] S42. Take five 50 mL volumetric flasks and add 5 mL of concentrated nitric acid to each. Then, add 0 mL, 0.50 mL, 1.50 mL, 2.50 mL, and 5.00 mL of a mixed standard solution with a concentration of 100 ug / mL (containing Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Pd, Sb, Se, Sn, Te, Ti, Zn, K, and Na) respectively. Dilute to the mark with water and mix well. The concentrations of the prepared mixed standard solutions are 0.00 ug / mL, 1.00 ug / mL, 3.00 ug / mL, 5.00 ug / mL, and 10.00 ug / mL, respectively. Measure the concentration of impurity elements in the A2 blank solution using an ICP-OES spectrometer and record it as C. b，i .

[0110] S43, Calculate the actual concentration of impurity elements: C 实际 = C i - C b,i .

[0111] S5. Based on the silver mass in step S3 and the actual concentration of impurity elements in step S4, the silver purity is calculated by normalization, which is the silver purity in the ceramic cup with a silver layer on the inner wall.

[0112] Formula for calculating the purity of silver in a ceramic cup with a silver layer on the inner wall:

[0113]

[0114] In the formula:

[0115] ω Ag —Silver purity in ceramic cups with a silver layer on the inner wall, expressed in parts per thousand (‰).

[0116] m Ag —The mass of silver in the ceramic cup with a silver layer on the inner wall, in grams (g);

[0117] C i —The concentration of impurity elements in solution A1, expressed in micrograms per milliliter (ug / mL).

[0118] C b , i —The concentration of impurity elements in the A2 blank solution, in micrograms per milliliter (ug / mL).

[0119] ∑ ( C i -C b , i— The sum of the concentrations of all impurity elements after deducting the blank, expressed in micrograms per milliliter (ug / mL).

[0120] In Example 1, the concentration of silver impurity elements in the ceramic cup with a silver layer on the inner wall is shown in Table 1.

[0121] Table 1. Concentration of silver impurity elements in ceramic cups with silver-coated walls.

[0122]

[0123] m Ag =2.4131g; ;

[0124] .

[0125] In Example 1, calculations showed that the mass of silver in the ceramic cup with a silver layer on the inner wall was 2.4131g, and the purity of the silver was 999.79‰.

[0126] Example 2

[0127] Embodiment 2 of the present invention provides a method for determining the quality and purity of silver in a ceramic cup with a silver layer on the inner wall, comprising the following steps:

[0128] S1. Place the ceramic cup with the silver layer on the inner wall into a 500 mL beaker, add 250 mL of nitric acid solution, heat on a 220 ℃ heating plate for 7 min until all the silver is dissolved, remove the ceramic cup, wash the ceramic cup with water 5 times, cool to room temperature, transfer the solution to a 500 mL volumetric flask, mix well, and record the solution as A1 and the volume as V0.

[0129] S2. Place a ceramic cup without a silver layer on the inner wall into a 500 mL beaker, add 250 mL of nitric acid solution, heat on a 220 ℃ heating plate for 7 min until all the silver is dissolved, remove the ceramic cup, wash the ceramic cup with water 5 times, cool to room temperature, transfer the solution to a 500 mL volumetric flask, mix well, and record the solution as A2 and the volume as V0.

[0130] S3, the mass of silver in the sample solution is determined by chemical titration, which is the mass of silver in the ceramic cup with a silver layer on the inner wall; including:

[0131] S31. Weigh 0.500 g of standard silver, accurate to 0.0001 g, and record the mass as m1. Place it in a 250 mL conical flask, add 10 mL of nitric acid solution, and heat it at a low temperature on an electric furnace until all the nitrogen oxides and yellow fumes disappear. Remove it and cool it to room temperature. Add 40 mL of deionized water and 2 mL of ferric ammonium sulfate solution. Add ammonium thiocyanate standard solution using a burette and titrate until the solution turns pale red, which is the titration endpoint. Record the volume of ammonium thiocyanate standard solution consumed as V1.

[0132] S32. Accurately transfer 50.00 mL of silver solution from solution A1 to a 250 mL conical flask, add 2 mL of ferric ammonium sulfate solution, add ammonium thiocyanate standard solution using a burette, and titrate until the solution turns pale pink as the titration endpoint. Record the volume of ammonium thiocyanate standard solution consumed as V2.

[0133] S33, Formula for calculating the mass of silver in a ceramic cup with a silver layer on the inner wall:

[0134] , ;

[0135] In the formula:

[0136] The titer of T-ammonium thiocyanate standard solution is expressed in grams per milliliter (g / mL).

[0137] m1—The mass of standard silver weighed, in grams (g).

[0138] E—Purity of standard silver;

[0139] V1 — The volume of ammonium thiocyanate standard solution consumed by the standard silver solution at the titration endpoint, expressed in milliliters (mL).

[0140] m Ag —The mass of silver in the ceramic cup with a silver layer on the inner wall, in grams (g);

[0141] V2—The volume of ammonium thiocyanate standard solution consumed by the sample solution at the titration endpoint, expressed in milliliters (mL).

[0142] 10 — Ratio of the final volume of the sample solution to the volume taken out.

[0143] S4, the concentrations of impurity elements in the sample solution and blank solution are determined by spectroscopic analysis, and the actual concentrations of impurity elements in silver are obtained by blank subtraction; including:

[0144] S41. Weigh five pure silver samples (silver purity not less than 99.999%), each weighing 0.4800 g. Place each sample in a polytetrafluoroethylene beaker and add 10 mL of concentrated nitric acid. Heat until completely dissolved. Transfer the silver solution to a 50 mL volumetric flask and add 0 mL, 0.50 mL, 1.50 mL, 2.50 mL, and 5.00 mL of a mixed standard solution with a concentration of 100 ug / mL (containing Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Pd, Sb, Se, Sn, Te, Ti, Zn, K, and Na) to the mark with water and mix well. The prepared mixed standard solutions had concentrations of 0.00 ug / mL, 1.00 ug / mL, 3.00 ug / mL, 5.00 ug / mL, and 10.00 ug / mL, respectively. The concentrations of impurity elements in solution A1 were determined using an ICP-OES spectrometer and denoted as C. i .

[0145] S42. Take five 50 mL volumetric flasks and add 10 mL of concentrated nitric acid to each. Then, add 0 mL, 0.50 mL, 1.50 mL, 2.50 mL, and 5.00 mL of a mixed standard solution with a concentration of 100 ug / mL (containing Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Pd, Sb, Se, Sn, Te, Ti, Zn, K, and Na) respectively. Dilute to the mark with water and mix well. The concentrations of the prepared mixed standard solutions are 0.00 ug / mL, 1.00 ug / mL, 3.00 ug / mL, 5.00 ug / mL, and 10.00 ug / mL, respectively. Measure the concentration of impurity elements in the A2 blank solution using an ICP-OES spectrometer and record it as C. b，i .

[0146] S43, Calculate the actual concentration of impurity elements: C 实际 = C i - C b,i .

[0147] S5. Based on the silver mass in step S3 and the actual concentration of impurity elements in step S4, the silver purity is calculated through normalization, which is the silver purity in the ceramic cup with a silver layer on the inner wall.

[0148] Formula for calculating the purity of silver in a ceramic cup with a silver layer on the inner wall:

[0149] ;

[0150] In the formula:

[0151] ω Ag—Silver purity in ceramic cups with a silver layer on the inner wall, expressed in parts per thousand (‰).

[0152] m Ag —The mass of silver in the ceramic cup with a silver layer on the inner wall, in grams (g);

[0153] C i —The concentration of impurity elements in solution A1, expressed in micrograms per milliliter (ug / mL).

[0154] C b , i —The concentration of impurity elements in the A2 blank solution, in micrograms per milliliter (ug / mL).

[0155] ∑ ( C i -C b , i — The sum of the concentrations of all impurity elements after deducting the blank, expressed in micrograms per milliliter (ug / mL).

[0156] In Example 2, the concentration of silver impurity elements in the ceramic cup with a silver layer on the inner wall is shown in Table 2.

[0157] Table 2. Concentration of silver impurity elements in ceramic cups with silver-coated walls.

[0158]

[0159] m Ag =4.8004g; ;

[0160] .

[0161] In Example 2, calculations showed that the mass of silver in the ceramic cup with a silver layer on the inner wall was 4.8004 g, and the purity of the silver was 999.83‰.

[0162] Standard Experiment Example 1

[0163] Accuracy tests were conducted using the national standard sample GBW(E)020104 and ceramic cups of the same batch and specifications as those in Example 1, which did not have a silver layer on the inner wall. The reference value of the standard sample was (999.94±0.03)‰. 2.0013g of silver standard sample was taken to conduct silver mass and purity tests.

[0164] S1. Place the national standard sample GBW(E)020104 in a ceramic cup without a silver layer on the inner wall, and place the whole cup in a 500mL beaker. Add 220mL of nitric acid solution and heat on a 200℃ heating plate for 5 minutes until all the silver is dissolved. Remove the ceramic cup, wash it with water 3 times, cool it to room temperature, transfer it to a 500mL volumetric flask, mix well, and record the solution as A1 and the volume as V0.

[0165] S2. Place a ceramic cup with no (or no) silver layer on the inner wall into a 500 mL beaker, add 220 mL of nitric acid solution, heat on a 200℃ heating plate for 5 min until all the silver is dissolved, remove the ceramic cup, wash the ceramic cup with water 3 times, cool to room temperature, transfer the solution to a 500 mL volumetric flask, mix well, and record the solution as A2 and the volume as V0.

[0166] S3, the mass of silver in the sample solution is determined by chemical titration, which is the mass of silver in the ceramic cup with a silver layer on the inner wall; including:

[0167] S31. Weigh 0.500 g of standard silver, accurate to 0.0001 g, and record the mass as m1. Place it in a 250 mL conical flask, add 10 mL of nitric acid solution, and heat it at a low temperature on an electric furnace until all the nitrogen oxides and yellow fumes disappear. Remove it and cool it to room temperature. Add 40 mL of deionized water and 1 mL of ferric ammonium sulfate solution. Add ammonium thiocyanate standard solution using a burette and titrate until the solution turns pale red, which is the titration endpoint. Record the volume of ammonium thiocyanate standard solution consumed as V1.

[0168] S32. Accurately transfer 50.00 mL of silver solution from solution A1 to a 250 mL conical flask, add 1 mL of ferric ammonium sulfate solution, and add ammonium thiocyanate standard solution using a burette. Titrate until the solution turns pale pink, which is the titration endpoint. Record the volume of ammonium thiocyanate standard solution consumed as V2.

[0169] S33, the formula for calculating the silver mass of the national standard sample GBW(E)020104 in step S1:

[0170] ,

[0171] In the formula:

[0172] The titer of T-ammonium thiocyanate standard solution is expressed in grams per milliliter (g / mL).

[0173] m1—The mass of standard silver weighed, in grams (g).

[0174] E—Purity of standard silver;

[0175] V1 — The volume of ammonium thiocyanate standard solution consumed by the standard silver solution at the titration endpoint, expressed in milliliters (mL).

[0176] m Ag —In step S1, the mass of silver in the national standard sample GBW(E)020104 is expressed in grams (g).

[0177] V2—The volume of ammonium thiocyanate standard solution consumed by the sample solution at the titration endpoint, expressed in milliliters (mL).

[0178] 10 — Ratio of the final volume of the sample solution to the volume taken out.

[0179] S4, the concentrations of impurity elements in the sample solution and blank solution are determined by spectroscopic analysis, and the actual concentrations of impurity elements in silver are obtained by blank subtraction; including:

[0180] S41. Weigh five pure silver samples (silver purity not less than 99.999%), each weighing 0.2001 g. Place each sample in a polytetrafluoroethylene beaker and add 5 mL of concentrated nitric acid. Heat until completely dissolved. Transfer the silver solution to a 50 mL volumetric flask and add 0 mL, 0.50 mL, 1.50 mL, 2.50 mL, and 5.00 mL of a mixed standard solution with a concentration of 100 ug / mL (containing Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Pd, Sb, Se, Sn, Te, Ti, Zn, K, and Na) to the mark with water and mix well. The prepared mixed standard solutions had concentrations of 0.00 ug / mL, 1.00 ug / mL, 3.00 ug / mL, 5.00 ug / mL, and 10.00 ug / mL, respectively. The concentrations of impurity elements in solution A1 were determined using an ICP-OES spectrometer and denoted as C. i .

[0181] S42. Take five 50 mL volumetric flasks and add 5 mL of concentrated nitric acid to each. Then, add 0 mL, 0.50 mL, 1.50 mL, 2.50 mL, and 5.00 mL of a mixed standard solution with a concentration of 100 ug / mL (containing Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Pd, Sb, Se, Sn, Te, Ti, Zn, K, and Na) respectively. Dilute to the mark with water and mix well. The concentrations of the prepared mixed standard solutions are 0.00 ug / mL, 1.00 ug / mL, 3.00 ug / mL, 5.00 ug / mL, and 10.00 ug / mL, respectively. Measure the concentration of impurity elements in the A2 blank solution using an ICP-OES spectrometer and record it as C. b，i .

[0182] S5, the formula for calculating the silver purity of the national standard sample GBW(E)020104 in step S1:

[0183] ;

[0184] In the formula:

[0185] ω Ag —In step S1, the silver purity of the national standard sample GBW(E)020104 is expressed in parts per thousand (‰).

[0186] m Ag —In step S1, the mass of silver in the national standard sample GBW(E)020104 is expressed in grams (g).

[0187] C i —The concentration of impurity elements in solution A1, expressed in micrograms per milliliter (ug / mL).

[0188] C b , i —The concentration of impurity elements in the A2 blank solution, in micrograms per milliliter (ug / mL).

[0189] ∑ ( C i -C b , i — The sum of the concentrations of all impurity elements after deducting the blank, expressed in micrograms per milliliter (ug / mL).

[0190] The concentrations of impurity elements in silver in the national standard sample GBW(E)020104 of Standard Experiment Example 1 are shown in Table 3.

[0191] Table 3 Concentration of impurity elements in silver

[0192]

[0193] m Ag =2.0014g; ;

[0194] ;

[0195] The calculated silver content in the standard sample was 2.0014 g, and the silver purity was 999.95‰. The test results met the reference values ​​for silver standard samples, indicating that the method is accurate and reliable.

[0196] Standard Experiment Example 2

[0197] Accuracy tests were conducted using the national standard sample GBW02752 and ceramic cups of the same batch and specifications from Example 2, which did not have a silver layer on the inner wall. The reference value of the standard sample was (999.94±0.04)‰. 4.0145g of silver standard sample was taken to conduct silver mass and purity tests.

[0198] S1. Place the national standard sample GBW02752 in a ceramic cup without a silver layer on the inner wall, and place the whole cup in a 500 mL beaker. Add 250 mL of nitric acid solution, heat on a 220 ℃ heating plate for 7 min until all the silver is dissolved. Remove the ceramic cup, wash it with water 5 times, cool it to room temperature, transfer it to a 500 mL volumetric flask, mix well, and record the solution as A1 and the volume as V0.

[0199] S2. Place a ceramic cup without a silver layer on the inner wall into a 500 mL beaker, add 250 mL of nitric acid solution, heat on a 220 ℃ heating plate for 7 min until all the silver is dissolved, remove the ceramic cup, wash the ceramic cup with water 5 times, cool to room temperature, transfer the solution to a 500 mL volumetric flask, mix well, and record the solution as A2 and the volume as V0.

[0200] S3, the mass of silver in the sample solution is determined by chemical titration, which is the mass of silver in the ceramic cup with a silver layer on the inner wall; including:

[0201] S31. Weigh 0.500 g of standard silver, accurate to 0.0001 g, and record the mass as m1. Place it in a 250 mL conical flask, add 10 mL of nitric acid solution, and heat it at a low temperature on an electric furnace until all the nitrogen oxides and yellow fumes disappear. Remove it and cool it to room temperature. Add 40 mL of deionized water and 2 mL of ferric ammonium sulfate solution. Add ammonium thiocyanate standard solution using a burette and titrate until the solution turns pale red, which is the titration endpoint. Record the volume of ammonium thiocyanate standard solution consumed as V1.

[0202] S32. Accurately transfer 50.00 mL of silver solution from solution A1 to a 250 mL conical flask, add 2 mL of ferric ammonium sulfate solution, add ammonium thiocyanate standard solution using a burette, and titrate until the solution turns pale pink as the titration endpoint. Record the volume of ammonium thiocyanate standard solution consumed as V2.

[0203] S33, the formula for calculating the silver mass of the national standard sample GBW02752 in step S1:

[0204] ,

[0205] In the formula:

[0206] The titer of T-ammonium thiocyanate standard solution is expressed in grams per milliliter (g / mL).

[0207] m1—The mass of standard silver weighed, in grams (g).

[0208] E—Purity of standard silver;

[0209] V1 — The volume of ammonium thiocyanate standard solution consumed by the standard silver solution at the titration endpoint, expressed in milliliters (mL).

[0210] m Ag —The mass of silver in the national standard sample GBW02752 in step S1, in grams (g);

[0211] V2—The volume of ammonium thiocyanate standard solution consumed by the sample solution at the titration endpoint, expressed in milliliters (mL).

[0212] 10 — Ratio of the final volume of the sample solution to the volume taken out.

[0213] S4, the concentrations of impurity elements in the sample solution and blank solution are determined by spectroscopic analysis, and the actual concentrations of impurity elements in silver are obtained by blank subtraction; including:

[0214] S41. Weigh five pure silver samples (silver purity not less than 99.999%), each weighing 0.4015 g. Place each sample in a polytetrafluoroethylene beaker and add 10 mL of concentrated nitric acid. Heat until completely dissolved. Transfer the silver solution to a 50 mL volumetric flask and add 0 mL, 0.50 mL, 1.50 mL, 2.50 mL, and 5.00 mL of a mixed standard solution with a concentration of 100 ug / mL (containing Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Pd, Sb, Se, Sn, Te, Ti, Zn, K, and Na) to the mark with water and mix well. The prepared mixed standard solutions had concentrations of 0.00 ug / mL, 1.00 ug / mL, 3.00 ug / mL, 5.00 ug / mL, and 10.00 ug / mL, respectively. The concentrations of impurity elements in solution A1 were determined using an ICP-OES spectrometer and denoted as C. i .

[0215] S42. Take five 50 mL volumetric flasks and add 10 mL of concentrated nitric acid to each. Then, add 0 mL, 0.50 mL, 1.50 mL, 2.50 mL, and 5.00 mL of a mixed standard solution with a concentration of 100 ug / mL (containing Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Pd, Sb, Se, Sn, Te, Ti, Zn, K, and Na) respectively. Dilute to the mark with water and mix well. The concentrations of the prepared mixed standard solutions are 0.00 ug / mL, 1.00 ug / mL, 3.00 ug / mL, 5.00 ug / mL, and 10.00 ug / mL, respectively. Measure the concentration of impurity elements in the A2 blank solution using an ICP-OES spectrometer and record it as C. b，i .

[0216] S5. Based on the silver mass in step S3 and the actual concentration of impurity elements in step S4, the silver purity is calculated through normalization, which is the silver purity of the national standard sample GBW02752 in step S1.

[0217] The formula for calculating the silver purity of the national standard sample GBW02752 in step S1 is as follows:

[0218] ;

[0219] In the formula:

[0220] ω Ag —Silver purity of national standard sample GBW02752 in step S1, in parts per thousand (‰);

[0221] m Ag —The mass of silver in the national standard sample GBW02752 in step S1, in grams (g);

[0222] C i —The concentration of impurity elements in solution A1, expressed in micrograms per milliliter (ug / mL).

[0223] C b , i —The concentration of impurity elements in the A2 blank solution, in micrograms per milliliter (ug / mL).

[0224] ∑ ( C i -C b , i — The sum of the concentrations of all impurity elements after deducting the blank, expressed in micrograms per milliliter (ug / mL).

[0225] The concentrations of impurity elements in the national standard sample GBW02752 silver in step S1 of standard experimental example 2 are shown in Table 4.

[0226] Table 4 Concentration of impurity elements in silver

[0227]

[0228] m Ag =4.0146g, ;

[0229] ;

[0230] The calculated silver mass of the national standard sample GBW02752 was 4.0146g, and the silver purity was 999.93‰. The test results are consistent with the reference values ​​of the silver standard sample, indicating that the method is accurate and reliable.

[0231] Comparative Example 1

[0232] The experiment was conducted using the traditional full-process blank experiment method (the experiment in S2 was conducted without adding the ceramic cup, only adding the reagent and water), and compared with the blank experiment in Example 1 where the inner wall of the ceramic cup did not have a silver layer. The experimental results are shown in Table 5.

[0233] , .

[0234] Table 5. Concentrations of impurity elements in silver measured in the full-process blank experiment.

[0235]

[0236] m Ag =2.4131g; ;

[0237] .

[0238] The purity of silver is 999.59‰. Bismuth was not detected in the blank solution obtained through the full-process blank experiment, leading to an overestimation of the bismuth impurity content after deducting the blank solution, resulting in a lower calculated silver purity. As can be seen from the experimental data of Comparative Example 1, bismuth was not detected in the blank solution using the conventional full-process blank experiment. However, in this embodiment of the invention, a ceramic cup without a silver layer on its inner wall was used for the blank experiment, and bismuth was detected in the blank solution. This indicates that during the dissolution of silver in the ceramic cup by the nitric acid solution, bismuth was dissolved from the ceramic, causing a systematic bias in the data results and resulting in a lower silver determination.

[0239] Comparative Examples 2-3

[0240] A blank experiment was conducted using ceramic cups without silver layer on the inner wall as described in Example 1 (four ceramic cups without silver layer on the inner wall were independently conducted in parallel experiments). The effect of the volume ratio of nitric acid to water (volume ratios of 1:1 (Comparative Example 2), 1:2 (Comparative Example 3), and 1:3 (Example 1)) on the amount of bismuth leached from the blank solution was investigated. The experimental results are shown in Table 6.

[0241] Table 6 Experimental results on bismuth dissolution in blank solution

[0242]

[0243] As shown in Table 6, as the volume ratio of nitric acid to water decreases, i.e., the acidity decreases (pH value decreases), the bismuth leaching amount in the ceramic decreases and tends to stabilize. Therefore, the optimal volume ratio of nitric acid to water in this embodiment of the invention is 1:3. Under this ratio, the bismuth leaching amount in the blank solution prepared by the nitric acid solution is the most stable, avoiding the situation where the bismuth concentration in the blank solution is higher than that in the sample due to the unstable bismuth leaching amount, which would make it impossible to calculate the purity result.

[0244] Comparative Examples 4-5, Example 3

[0245] A blank experiment was conducted using ceramic cups without silver layer on the inner wall as in Example 1 (four ceramic cups without silver layer on the inner wall were independently tested in parallel). The effect of dissolution temperature (sample dissolution temperature 240℃ (Comparative Example 4), 260℃ (Comparative Example 5), 200℃ (Example 1), 220℃ (Example 3)) on the amount of bismuth leached from the blank solution was investigated. The experimental results are shown in Table 7.

[0246] Table 7 Experimental results on bismuth dissolution in blank solution

[0247]

[0248] As shown in Table 7, the higher the sample dissolution temperature, the higher the bismuth dissolution amount, which will lead to inconsistent bismuth concentration and dissolution amount in the blank solution. On the other hand, if the sample dissolution temperature is too low, the silver dissolution rate will be slow, thereby increasing the dissolution time. When the sample dissolution temperature is between 200-220℃, the bismuth dissolution amount in the blank solution tends to be stable.

[0249] Comparative Examples 6-7, Example 4

[0250] A blank experiment was conducted using ceramic cups without silver layer on the inner wall as in Example 1 (four ceramic cups without silver layer on the inner wall were tested independently). The effect of dissolution time (10 min (Comparative Example 6), 15 min (Comparative Example 7), 5 min (Example 1), 7 min (Example 4)) on the amount of bismuth dissolved in the blank solution was investigated. The experimental results are shown in Table 8.

[0251] Table 8 Experimental results on bismuth dissolution in blank solution

[0252]

[0253] As shown in Table 8, the longer the sample dissolution time, the higher the bismuth dissolution amount. Moreover, the bismuth concentration and dissolution amount in the blank solution are not uniform, resulting in an uncontrollable blank concentration. The dissolution time is controlled at 5-7 min, which can ensure that the silver is dissolved and make the bismuth dissolution amount in the blank tend to be stable.

[0254] By using the optimal volume fraction of nitric acid solution, the optimal volume of nitric acid, the optimal dissolution temperature, and the optimal dissolution time, only by combining and unifying the above conditions can the amount of bismuth leached from the ceramic be minimized and stabilized. This solves the problem that the high and unstable amount of bismuth leaching leads to large fluctuations in blank difference, resulting in poor precision and low accuracy of silver purity determination results.

[0255] This determination method forms a closed-loop error elimination and accurate calculation system through close coordination between each step. It first employs a dual-sample parallel digestion mechanism, simultaneously performing identical nitric acid heating digestion on both the "silver-layered ceramic cup" (sample) and the "silver-free ceramic cup from the same batch" (blank). This ensures that the impurities (especially bismuth) dissolved from the ceramic matrix are highly consistent under the same acidity, temperature, and time. This forms the basis for accurate background interference subtraction. Next, a step-by-step detection and data correlation mechanism is used, directly determining the silver content in the sample solution using ammonium thiocyanate titration. Since bismuth does not interfere with the titration reaction, this step can independently and accurately obtain the mass of silver. ICP-OES is used to determine the impurity concentration in the sample solution and the blank solution respectively. The titration method provides the numerator (mass of silver), while the spectroscopic method provides the denominator (mass of impurities). The sum of the silver mass and the impurity mass is the total sample mass, with both data mutually supporting each other. Finally, a difference-subtraction normalization calculation mechanism is used to accurately remove the true "silver impurities," thereby eliminating the systematic errors introduced by the ceramic matrix. Furthermore, by optimizing the nitric acid ratio (1:3) and controlling the temperature / time, the amount of bismuth dissolved in the blank group was both low and stable. This invention, by combining physical batch-specific blank controls with chemically optimized digestion conditions, and using titration and spectroscopy combined with other techniques, successfully constructed a silver quality and purity determination system that can eliminate interference from ceramic matrices, thus achieving accurate detection of precious metals in complex matrices.

[0256] In summary, this invention provides a method for determining the mass and purity of silver in ceramic cups with a silver layer on the inner wall, relating to the field of precious metal analysis and detection technology. Addressing the challenges of existing physical methods failing to remove the silver layer and chemical methods encountering interference from bismuth in the ceramic matrix during purity determination, this invention uses silver-free ceramic cups from the same batch as a specific blank control. The sample and blank sample are simultaneously digested using an optimized ratio of nitric acid solution under specific temperature / time conditions. The absolute mass of silver is accurately determined by ammonium thiocyanate titration, and the impurity concentrations in the sample and blank solutions are determined separately using ICP-OES spectroscopy. Background interference such as bismuth dissolved from the ceramic is accurately subtracted using a difference method, and the silver purity is finally calculated through normalization. This method enables continuous and accurate determination of silver mass and purity with a single sample dissolution, effectively solving the problem of interference from complex matrices, significantly improving the precision and accuracy of detection, and providing a feasible technical solution for the quality inspection of silver-layered ceramic products.

[0257] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A method for determining the quality and purity of silver in a ceramic cup with a silver layer on its inner wall, characterized in that, Includes the following steps: S1, Dissolution of the sample to be tested: Place the ceramic cup containing the silver layer on the inner wall of the sample to be tested in an acid solution, control the dissolution temperature and dissolution time to dissolve the silver layer, cool and then make up to a final volume to obtain the sample solution; S2, Sample blank control: Select a ceramic cup with no silver layer on the inner wall from the same batch and specifications as the ceramic cup to be tested, place it in the same acid solution of the same volume as in step S1, process it under the same dissolution temperature and dissolution time conditions, cool it and make up the volume to obtain a blank solution. S3, Silver mass determination: The mass of silver in the sample solution is determined by chemical titration, which is the mass of silver in the ceramic cup with a silver layer on the inner wall; S4, Determination of impurity element concentration: The concentration of impurity elements in the sample solution and blank solution is determined by spectroscopic analysis. The actual concentration of impurity elements in silver is obtained by blank subtraction. S5, Silver purity calculation: Based on the silver mass in step S3 and the actual concentration of impurity elements in step S4, the silver purity is calculated through normalization, which is the silver purity in the ceramic cup with a silver layer on the inner wall.

2. The method for determining the quality and purity of silver in a ceramic cup with a silver layer on the inner wall according to claim 1, characterized in that, In steps S1 and S2, the acid solution is a nitric acid solution, prepared by mixing concentrated nitric acid with water at a volume ratio of 1:

3.

3. The method for determining the quality and purity of silver in a ceramic cup with a silver layer on the inner wall according to claim 1, characterized in that, In steps S1 and S2, the dissolution temperature is 200~220℃ and the dissolution time is 5~7min.

4. The method for determining the quality and purity of silver in a ceramic cup with a silver layer on the inner wall according to claim 1, characterized in that, In step S3, the chemical titration method is the ammonium thiocyanate titration method, using ferric ammonium sulfate as an indicator.

5. The method for determining the quality and purity of silver in a ceramic cup with a silver layer on the inner wall according to claim 4, characterized in that, In step S3, the specific process for determining the silver mass is as follows: S31. Weigh out a predetermined mass of standard silver, dissolve it in an acid solution, add ferric ammonium sulfate indicator, titrate with ammonium thiocyanate standard solution to a pale red endpoint, record the volume consumed V1, and calculate the titer T. S32, take a portion of the solution from the sample solution, add ferric ammonium sulfate indicator, titrate with ammonium thiocyanate standard solution to a light red endpoint, and record the volume consumed V2; S33, calculate silver mass: m Ag = T×V2×(V0 / V 分取 ); Where, m Ag V0 is the mass of silver in the ceramic cup containing a silver layer on the inner wall; V0 is the final volume of the sample solution .... 分取 V1 represents the volume of ammonium thiocyanate standard solution consumed by the standard silver solution at the titration endpoint; V2 represents the volume of ammonium thiocyanate standard solution consumed by the sample solution at the titration endpoint. The formula for calculating the titer T of the ammonium thiocyanate standard solution is: T = (m1 × E) / V1; Where m1 is the mass of standard silver weighed; E is the purity of the standard silver.

6. The method for determining the quality and purity of silver in a ceramic cup with a silver layer on the inner wall according to claim 1, characterized in that, In step S4, the concentration of impurity elements is determined by inductively coupled plasma optical emission spectrometry (ICP-OES); the impurity elements include at least one or more of Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Pd, Sb, Se, Sn, Te, Ti, Zn, K, and Na.

7. The method for determining the quality and purity of silver in a ceramic cup with a silver layer on the inner wall according to claim 5, characterized in that, The specific process for determining the impurity concentration in step S4 is as follows: S41, Weigh a predetermined amount of pure silver and prepare a series of standard solutions containing a silver matrix, ensuring that the silver-containing standard solution medium is consistent with the sample solution medium. Use ICP-OES to determine the concentration C of impurity elements in the sample solution. i ; S42, prepare a series of silver-free standard solutions, ensuring the medium of the silver-free standard solutions is consistent with that of the blank solution. The concentration of impurity elements (C) in the blank solution is determined using ICP-OES. b,i ; S43, Calculate the actual concentration of impurity elements: C 实际 = C i - C b,i ; Wherein, the impurity elements are, in order, Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Pd, Sb, Se, Sn, Te, Ti, Zn, K, and Na, and i is the i-th impurity element among the impurity elements.

8. The method for determining the quality and purity of silver in a ceramic cup with a silver layer on the inner wall according to claim 7, characterized in that, The formula for normalizing silver purity in step S5 is as follows: ； Where, ω Ag The purity of silver in a ceramic cup with a silver layer on its inner wall; C i This represents the concentration of impurity elements in the sample solution. C b , i This represents the concentration of impurity elements in the blank solution. ∑ ( C i -C b , i ) represents the sum of the concentrations of all impurity elements after deducting blanks.

9. The method for determining the quality and purity of silver in a ceramic cup with a silver layer on the inner wall according to claim 8, characterized in that, In step S41, the mass of pure silver weighed is one-tenth of the mass of silver in the ceramic cup with a silver layer on the inner wall in step S33.

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