Method for testing platinum content in platinum compound solution

Abstract

The invention discloses a method for testing the content of platinum in a platinum compound solution, and belongs to the technical field of analytical testing. According to the test method, an ammonium chloride precipitation gravimetric method is replaced by a hydrogen reduction gravimetric method, platinum ions in a platinum compound solution are reduced into elemental platinum in a hydrogen reduction mode, and the content of platinum in the solution is calculated by weighing the weight of a reduced platinum sinter and subtracting the content of impurity elements in the platinum sinter at the same time. According to the method, the platinum content in the platinum compound solution can be accurately and quantitatively analyzed, the operation process is simple, good repeatability is achieved, the range of multiple analysis results of the same sample is smaller than or equal to 0.05% and is far lower than the repeatability limit 0.2% of a national standard method, the analysis accuracy is guaranteed, and meanwhile the analysis efficiency is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of analysis and testing, and in particular relates to a method for testing the platinum content in a platinum compound solution. Background Art

[0002] In modern industry, platinum and its compound products are increasingly used, due to its superior physical, chemical and electrical properties. Platinum nitrate solution is mainly used for loading platinum coatings on automobile exhaust catalytic converters and in fine chemicals. It can also be used as an important intermediate for the preparation of homogeneous catalysts. It is an indispensable catalyst raw material for chemical and fine chemical industries. Dinitrodiammine platinum solution is mainly used for platinum plating in cyanide-free electroplating. It is also suitable for platinum plating on the surface of electronic components. This solution is used for electroplating, and the resulting coating has high hardness and low resistance. It can also be used to synthesize dyes, medicines and pesticide intermediates. Both of these platinum compounds have extremely important application value. Platinum is a rare and valuable metal. Therefore, the accurate determination of the platinum content in platinum compound solutions is also very important.

[0003] At present, the domestic determination methods of platinum content mostly use ammonium chloride precipitation method and potassium permanganate potentiometric titration method, and some use ICP analysis method. The characteristics of ammonium chloride precipitation method and potassium permanganate potentiometric titration method are high analysis accuracy, but the analysis process is long, which is suitable for platinum compounds with a platinum content higher than 5% (repeatability limit is 0.2%). The characteristic of ICP analysis method is fast analysis speed, but it is not suitable for the detection of high-content samples. When the platinum content in the platinum solution is higher than 5%, the test stability of ICP analysis method is poor. Summary of the invention

[0004] The concentration range of domestically produced platinum nitrate solution and diamine dinitrosoplatinum solution products is 10% to 20%. For the detection of platinum content in platinum nitrate solution or diamine dinitrosoplatinum solution, the existing platinum content determination method has the technical problem of not being able to simultaneously meet the requirements of high efficiency, rapidity, strong stability and wide range of platinum content. In response to this technical problem, the new detection method developed by the present invention can test the platinum content in platinum compounds in the range of 5% to 40%, meet the product testing requirements, and have the characteristics of simple analysis process and high accuracy.

[0005] The technical solution adopted by the present invention to solve the technical problem is: providing a new method for testing the platinum content in a platinum compound solution, using a hydrogen reduction weight method instead of an ammonium chloride precipitation weight method to detect the platinum content in the platinum compound solution; the platinum compound solution is a platinum nitrate solution or a dinitrosodiammine platinum solution.

[0006] The method for testing the platinum content in a platinum compound solution specifically comprises the following steps:

[0007] a. The platinum compound solution is concentrated and evaporated to dryness, cooled and placed in a tubular furnace through a mixture of hydrogen and nitrogen for hydrogen reduction, and then dried and cooled to room temperature to obtain a platinum sintered product;

[0008] b. Mix the platinum sinter and aqua regia, use microwave digestion to completely dissolve the platinum sinter, and then transfer to a 100 ml volumetric flask with ultrapure water to make up to volume to obtain a sample solution, and prepare a reagent blank solution and an impurity standard solution respectively;

[0009] c. Rationally select ICP instrument detection conditions, establish instrument detection methods, and draw standard curves for each impurity element;

[0010] d. The sample solution and the reagent blank solution obtained in step b are respectively introduced into the ICP instrument and tested according to the instrument detection conditions, and the contents of 30 impurity elements Ag, Al, As, Au, B, Bi, Ba, Cd, Co, Cr, Cu, Fe, Ir, Mg, Mn, Mo, Ni, Pb, Pd, Rh, Ru, Sb, Si, Sn, Ti, Li, Zn, Zr, Na, and K in the sample solution and the reagent blank solution are determined according to the standard curve;

[0011] e. Calculate the weight of impurities in the platinum sintered product based on the obtained impurity element content, and calculate the platinum content in the platinum compound solution based on the obtained impurity weight.

[0012] In the above step a, the concentration and evaporation are as follows: 0.5 to 4 g of the platinum compound solution is weighed into a quartz or ceramic crucible, placed on an electric heating plate and slowly heated until the water is completely concentrated and evaporated, and then removed and cooled to room temperature.

[0013] In the above step a, the volume concentration of hydrogen in the hydrogen-nitrogen mixture is 3.5% to 3.9%, and the gas flow rate is 5 to 6 L / min.

[0014] In the above step a, the hydrogen reduction temperature is kept constant at 400-600° C., and the hydrogen reduction time is greater than 1 hour.

[0015] In the above step b, the volume of the aqua regia solution is 8-10 ml, and the HCl and HNO 3 The volume ratio is 8:2 to 8:4.

[0016] In the above step b, the microwave digestion temperature is 200-220° C., and the microwave digestion time is 30-40 minutes.

[0017] In the above step b, the concentrations of the impurity standard solutions are 0.2 μg / ml, 0.5 μg / ml, and 2 μg / ml.

[0018] Furthermore, the preparation method of the above-mentioned impurity standard solution is: according to the matrix classification of each impurity element standard solution, 1 ml of 1000 μg / ml impurity standard solution of the same matrix is ​​taken into a 100 ml volumetric flask, and diluted to the scale with ultrapure water to prepare a 10 μg / ml impurity transfer solution, and then 2 ml, 5 ml, and 20 ml are taken from the transfer solution to a 100 ml volumetric flask, respectively, and diluted to the scale with ultrapure water to prepare impurity standard solutions with concentrations of 0.2 μg / ml, 0.5 μg / ml, and 2 μg / ml.

[0019] In the above step e, the calculation formula for the weight of impurities in the platinum sintered product is:

[0020]

[0021] In the formula, C i0 C is the concentration of an impurity element in the blank solution of the reagent measured by ICP in step d, μg / ml; i1 is the concentration of a certain impurity element in the sample solution measured by ICP in step d, μg / ml; Wi is the mass of a certain impurity in the platinum sintered product, g.

[0022] In the above step e, the calculation formula for the platinum content in the platinum compound solution is:

[0023]

[0024] Where M 0 is the weight of the platinum compound solution in step a, g; ∑W i is the total weight of impurities in the platinum sinter, g; M 1 M is the mass of the container containing the platinum sinter in step a, g; 2 is the mass of the empty container after removing the platinum sintered product in step a, g.

[0025] The beneficial effects of the present invention are as follows: the present invention develops a new detection mode, using hydrogen reduction weight method to replace ammonium chloride precipitation weight method to detect the platinum content in the platinum compound solution, filling the gap in this detection method in China. The method of the present invention is simple in process, less time-consuming, simplifies the processing flow, and improves work efficiency; it is relatively safe, does not use chemical reagents for reduction, and the hydrogen used for reduction is a nitrogen-hydrogen mixed gas. Under the condition of ensuring that the platinum metal is completely reduced, the volume concentration of hydrogen is lower than the explosion limit; the method of the present invention is applicable to a wide range of test concentrations, and the test platinum concentration range (5% to 40%) can cover the concentration range of the platinum compound solution product (10% to 20%); the method of the present invention has good repeatability, and the extreme difference of the analysis value of the platinum content of the same sample is ≤0.05%, which is better than the repeatability limit of 0.2% in the national standard method; the method of the present invention has high test accuracy, and the method reduces the mass of impurity elements reduced together with platinum, so that the test result has high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The figure is a schematic diagram of the operation flow of the method of the present invention. DETAILED DESCRIPTION

[0027] The technical solution of the present invention can be specifically implemented in the following manner.

[0028] 1. Weighing and concentration of sample solution: Weigh 0.5-4 g (accurate to 0.1 mg) of platinum compound solution (platinum nitrate solution or dinitrodiammine platinum solution) into a 25 ml quartz or ceramic crucible, place it on an electric heating plate and slowly heat until the water is completely concentrated and evaporated, then remove it and let it cool to room temperature.

[0029] 2. Sample hydrogen reduction: Place the crucible containing the evaporated sample in an atmosphere tube furnace, pass a hydrogen-nitrogen mixture (hydrogen volume concentration of 3.5% to 3.9%), the mixed gas flow rate is 5 to 6 L / min, the furnace temperature is kept constant at 400 to 600°C for more than 1 hour, and the metal elements in the sample are hydrogen reduced.

[0030] 3. Drying and cooling of samples: Take out the crucible containing the platinum sintered product after hydrogen reduction from the furnace tube and place it in a dryer to cool to room temperature.

[0031] 4. Weighing of platinum sinter: weigh the crucible with platinum sinter M 1 (accurate to 0.01 mg), use a clean brush or fine brush to sweep the reduced platinum sintered material in the crucible into the digestion tank, and weigh the empty crucible M 2 The weight of the platinum sinter is calculated by weighing the crucible weight difference.

[0032] 5. Dissolve the sintered platinum: Use 8-10 ml of aqua regia (HCl and HNO 3 The volume ratio is 8:2-8:4), and the sample solution is obtained by using a microwave digestion device at 200-220°C for 30-40 minutes (in order to completely dissolve the impurities in the platinum sinter). After the dissolution is completed, the sample solution is transferred to a 100ml volumetric flask with ultrapure water to obtain a sample solution. At the same time, a reagent blank solution is prepared.

[0033] Determination of impurity element content in platinum sintered products.

[0034] 6. Use plasma emission spectrometer to determine the metal impurity elements that may appear in the platinum sintered product:

[0035] 6.1 Preparation of impurity standard solution: Take 1 ml of 1000 μg / ml impurity standard solution of 30 elements including Ag, Al, As, Au, B, Bi, Ba, Cd, Co, Cr, Cu, Fe, Ir, Mg, Mn, Mo, Ni, Pb, Pd, Rh, Ru, Sb, Si, Sn, Ti, Li, Zn, Zr, Na, and K in a 100 ml volumetric flask (prepare according to the different matrix of each impurity element standard solution), and dilute to the scale with ultrapure water to prepare a 10 μg / ml impurity transfer solution. Take 2 ml, 5 ml, and 20 ml of the transfer solution respectively and put them into a 100 ml volumetric flask, dilute to the scale with ultrapure water to prepare impurity standard solutions with concentrations of 0.2 μg / ml, 0.5 μg / ml, and 2 μg / ml.

[0036] 6.2 Establishment of method file: Establish instrument test method file, select the elements and characteristic spectral lines to be measured, set the instrument's pump speed, delay time, reading time, stabilization time, nebulizer gas flow rate, plasma gas flow rate, auxiliary gas flow rate, observation method and other parameter conditions, and fill in the standard sample quantity, concentration, standard method and other information.

[0037] 6.3 Establishment of standard curve: Test ultrapure water as the blank of the standard curve, test the standard solutions of impurity elements of various concentrations, and establish the standard curve of each impurity element. The instrument will automatically fit the standard curve and linear correlation coefficient of each element. During the measurement, the instrument will automatically convert the response intensity value into the sample content value.

[0038] 6.4 Sample testing: Detect the content of each impurity element in the blank solution of the test reagent; Detect the content of each impurity element in the solution of the platinum sintered product.

[0039] 7. Calculation of results:

[0040] 7.1 Calculation of the weight of impurities in sintered material:

[0041]

[0042] C i0 : ICP detection of a certain impurity concentration in blank solution, μg / ml;

[0043] C i1 : ICP detection of impurity concentration in sample solution, μg / ml;

[0044] Wi: The mass of an impurity in the sintered material, g.

[0045] 7.2 Calculation of platinum content in the sample, the calculation formula is as follows:

[0046]

[0047] M 0 : The amount of platinum compound sample, g;

[0048] ∑W i : Total weight of impurities in platinum sinter, g;

[0049] M 1 : Weight of crucible + platinum sintered product, g;

[0050] M 2 : Crucible weight, g.

[0051] 8. Verification of test results: In order to determine the consistency of the test results of the hydrogen reduction weight method and the precipitation weight method, the platinum nitrate solution and the diamine dinitrosoplatinum solution were compared and tested by the hydrogen reduction weight method and the saturated ammonium chloride precipitation weight method. The test results showed that the test results of the two methods were in good consistency.

[0052] The technical solution and effects of the present invention are further illustrated below through practical examples.

[0053] Example

[0054] (1) Weigh 1.5 g of platinum nitrate solution (concentration of about 15%) and 1.3 g (accurate to 0.1 mg) of dinitrodiammine platinum solution (concentration of about 17%) into a 25 ml quartz crucible, and make parallel samples N = 3 (6 in total) at the same time.

[0055] (2) Place the crucible containing the sample on a 150°C electric heating plate to slowly evaporate the concentrated sample water; place the concentrated and evaporated sample in a tubular furnace, pass a nitrogen-hydrogen mixture with a hydrogen volume concentration of about 3.5% at 6 L / min, and heat it at a constant temperature of 400°C for 1 hour; take the crucible containing the platinum sintered product out of the tubular furnace and place it in a desiccator to cool to room temperature.

[0056] (3) Weigh the crucible with the platinum sinter, use a clean brush to sweep the reduced platinum sinter in the crucible into a microwave digestion tank, and then weigh the empty crucible, with the weight accurate to 0.01 mg; add 10 ml of aqua regia (HCl:HNO3=8:2) to the microwave digestion tank containing the platinum sinter, and make a reagent blank at the same time, using a microwave digestion equipment to digest at 210°C for 30 minutes; transfer the digested solution to a 100 ml volumetric flask with ultrapure water and make up to volume to obtain 6 sample solutions and 1 reagent blank solution.

[0057] (4) Establish instrument test methods, set instrument parameter information, and establish instrument test standard curves; test 30 impurity element standard solutions of different concentrations and establish standard curves.

[0058] (5) Test the reagent blank solution and sample solution in turn, and calculate the impurity content and platinum content according to Formulas 7.1 and 7.2.

[0059] The above two samples were compared and tested by ammonium chloride precipitation weight method. The results of the platinum nitrate solution and the dinitrodiammine platinum solution tested by hydrogen reduction weight method and ammonium chloride precipitation weight method are shown in Table 1. The test results have good consistency.

[0060] Table 1 Comparison of analysis results of hydrogen reduction gravimetric method and ammonium chloride precipitation gravimetric method

[0061]

Claims

1. A method for testing the platinum content in a platinum compound solution, characterized in that: The platinum compound solution is a platinum nitrate solution or a dinitrosodiammine platinum solution. The specific testing method comprises the following steps: a. The platinum compound solution is concentrated and evaporated to dryness, cooled and placed in a tubular furnace through a mixture of hydrogen and nitrogen for hydrogen reduction, and then dried and cooled to room temperature to obtain a platinum sintered product; b. Mix the platinum sinter and aqua regia, use microwave digestion to completely dissolve the platinum sinter, and then transfer to a 100 ml volumetric flask with ultrapure water to make up to volume to obtain a sample solution, and prepare a reagent blank solution and an impurity standard solution respectively; c. Rationally select ICP instrument detection conditions, establish instrument detection methods, and draw standard curves for each impurity element; d. The sample solution and the reagent blank solution obtained in step b are respectively introduced into the ICP instrument and tested according to the instrument detection conditions, and the contents of 30 impurity elements Ag, Al, As, Au, B, Bi, Ba, Cd, Co, Cr, Cu, Fe, Ir, Mg, Mn, Mo, Ni, Pb, Pd, Rh, Ru, Sb, Si, Sn, Ti, Li, Zn, Zr, Na, and K in the sample solution and the reagent blank solution are determined according to the standard curve; e. Calculate the weight of impurities in the platinum sintered product based on the obtained impurity element content, and calculate the platinum content in the platinum compound solution based on the obtained impurity weight.

2. The method for testing the platinum content of a platinum compound solution according to claim 1, characterized in that: In step a, the concentration and evaporation are as follows: 0.5 to 4 g of the platinum compound solution is weighed into a quartz or ceramic crucible, placed on an electric heating plate and slowly heated until the water is completely concentrated and evaporated, and then removed and cooled to room temperature.

3. The method for testing the platinum content of a platinum compound solution according to claim 1, characterized in that: In step a, the volume concentration of hydrogen in the hydrogen-nitrogen mixture is 3.5% to 3.9%, and the gas flow rate is 5 to 6 L / min.

4. The method for testing the platinum content of a platinum compound solution according to claim 1, characterized in that: In step a, the hydrogen reduction temperature is kept constant at 400-600° C., and the hydrogen reduction time is greater than 1 hour.

5. The method for testing the platinum content of a platinum compound solution according to claim 1, characterized in that: In step b, the volume of the aqua regia liquid is 8 to 10 ml, and the volume ratio of HCl to HNO3 in the aqua regia liquid is 8:2 to 8:

4.

6. The method for testing the platinum content of a platinum compound solution according to claim 1, characterized in that: In step b, the microwave digestion temperature is 200-220° C., and the microwave digestion time is 30-40 minutes.

7. The method for testing the platinum content of a platinum compound solution according to claim 1, characterized in that: In step b, the concentrations of the impurity standard solutions are 0.2 μg / ml, 0.5 μg / ml, and 2 μg / ml.

8. The method for testing the platinum content of a platinum compound solution according to claim 7, characterized in that: The preparation method of impurity standard solution is as follows: according to the matrix classification of each impurity element standard solution, take 1 ml of 1000μg / ml impurity standard solution of the same matrix into a 100ml volumetric flask, and dilute it to the scale with ultrapure water to prepare a 10μg / ml impurity transfer solution, and then take 2ml, 5ml, and 20ml from the transfer solution into a 100ml volumetric flask, dilute it to the scale with ultrapure water to prepare impurity standard solutions with concentrations of 0.2μg / ml, 0.5μg / ml, and 2μg / ml.

9. The method for testing the platinum content of a platinum compound solution according to claim 1, characterized in that: In step e, the calculation formula for the weight of impurities in the platinum sintered product is: In the formula, C i0 C is the concentration of an impurity element in the blank solution of the reagent measured by ICP in step d, μg / ml; i1 is the concentration of a certain impurity element in the sample solution measured by ICP in step d, μg / ml; Wi is the mass of a certain impurity in the platinum sintered product, g.

10. The method for testing the platinum content of a platinum compound solution according to claim 1, characterized in that: In step e, the calculation formula for the platinum content in the platinum compound solution is: Wherein, M0 is the amount of platinum compound solution weighed in step a, g; ∑W i is the total weight of impurities in the platinum sinter, g; M1 is the mass of the container containing the platinum sintered product in step a, g; M2 is the mass of the empty container after the platinum sintered product is removed in step a, g.

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