A method for detecting the content of palladium in a noble metal palladium compound

Abstract

The present invention relates to a method for detecting the content of palladium in a noble metal palladium compound, comprising the following steps: preparing a solution of a noble metal palladium compound sample to be detected; preparing a noble metal standard solution; using energy-type X-ray fluorescence emission spectroscopy (EDX) to detect the noble metal standard solution at different concentrations, and obtaining a standard working curve; using EDX to detect the noble metal element in the solution to be detected; and calculating the content of the noble metal element in the noble metal compound by the standard working curve. A method for detecting the content of palladium in a noble metal palladium compound of the present invention, the method for preparing the solution to be detected can make the solution matrix uniform and stable, and reduce the matrix effect; the standard working curve can achieve precise detection and high accuracy within the optimal metal concentration range, the method is simple and efficient, and different types of palladium compound samples are selected for testing, the detection effect is excellent, and the scope of use is wide.

Description

Technical Field

[0001] The present invention relates to the field of detection and analysis technology, and in particular to a method for detecting the content of palladium in a noble metal palladium compound. Background Art

[0002] Palladium precious metal compounds are widely used. Palladium compounds are used as catalysts in organic synthesis and are known as the heart of the organic synthesis industry. They have broad market prospects. Traditional palladium compounds can also be directly used in the circuit board printing industry for chemical plating, electroplating, etc. In addition, a large number of palladium compounds are also used in automobile exhaust three-way catalysts.

[0003] During the transaction of precious metal compounds, each company pays the most attention to the content of metal elements. Disputes often arise due to inconsistent metal content detection. Therefore, efficient and reliable detection methods are needed. A series of standard detection methods have been established for the detection of metal content in precious metal compounds. The main methods are: dimethylglyoxime gravimetric method for palladium content detection YS / T1320.1-2019, dimethylglyoxime complexometric titration method for palladium content detection GB / T23276-2009, inductively coupled plasma detection method for palladium content detection GB / T17418.6-2010, hydrazine hydrate reduction gravimetric method for palladium content detection YS / T1395.1-2020. However, due to the inherent properties of palladium compounds, there are some applicability issues in the current methods. For example, in the complex drop method, the judgment of the end point color depends on human visual observation, which is highly subjective and difficult to avoid detection deviations. The palladium weight method has high accuracy, but the detection process is complex, time-consuming, and inefficient, and is not suitable for rapid detection of large quantities of samples. The inductively coupled plasma detection method has large deviations for high-content palladium detection and is not suitable for high-content palladium compound detection. The hydrazine hydrate reduction weight method has a small range of application for samples and is not applicable to most palladium compounds. Although EDX has unique advantages in detection methods, such as fast and high precision, the detection of chlorine element spectrum is close to the palladium spectrum, which is easy to interfere with the detection and cause detection deviations. Therefore, efficient and accurate detection of metal content in precious metal compounds is a pain point in the industry. Summary of the invention

[0004] The present invention aims to propose a method for detecting the content of metal elements in precious metal compounds, so as to provide a simple, high-accuracy, high-precision method for detecting the content of precious metal palladium.

[0005] A method for detecting the content of palladium in a noble metal palladium compound comprises the following steps:

[0006] S1 Pretreatment of precious metal palladium compound: transfer the precious metal palladium compound into a beaker, add aqua regia, and transfer to an electric heating plate for nitrolysis;

[0007] After the nitration is completed, hydrochloric acid is added to decompose the residual nitrate. After the nitrate is completely decomposed, sodium borate is added and evaporated at low temperature to a nearly dry state to completely remove free chlorine.

[0008] After cooling, dissolve it with boric acid solution, transfer it to a volumetric flask for weighing, and obtain a solution of precious metal palladium compound to be tested;

[0009] Preparation method of S2 precious metal standard solution: transfer palladium sheet / powder into a beaker, add aqua regia, transfer to an electric heating plate for nitrolysis,

[0010] After the nitration is completed, hydrochloric acid is added to decompose the remaining nitrate. After the nitrate is completely nitrated, sodium borate is added and evaporated at low temperature to a nearly dry state to completely remove free chlorine.

[0011] After cooling, dissolve it with boric acid, transfer it to a volumetric flask for weighing, and obtain a noble metal standard solution. Transfer the noble metal standard solution to a volumetric flask for weighing, and after gradual dilution, six standard solutions with different metal contents can be obtained respectively;

[0012] S3 precision instrument analysis method for detection: The precision instrument analysis method is energy-based X-ray fluorescence emission spectroscopy, and the detection steps are as follows:

[0013] According to the preparation method in S2, six noble metal standard solutions with palladium concentrations of 200 ppm, 400 ppm, 800 ppm, 1600 ppm, 3000 ppm and 6000 ppm were prepared respectively, and an EDX standard working curve was drawn using the prepared noble metal standard solutions at different concentrations;

[0014] The detection parameters of the energy-type X-ray fluorescence emission spectrometry are set as follows: collimator 10mm, atmosphere-air, sample cup-Mylar film, voltage 50kv, current 100uA, energy line PdKa is 21keV, energy range 21-22keV, integration time 100s, DT30%, and quantitative method is integration.

[0015] Preferably, the noble metal palladium compound includes but is not limited to chloropalladic acid, sodium chloropalladate, palladium chloride, palladium sulfate, palladium nitrate, tetraamminepalladium sulfate, palladium acetate, trimethylpalladium acetate, dichlorotetraamminepalladium, dichlorodiamminepalladium, palladium hydroxide, 1,2-bis(diphenylphosphine)ethanepalladium chloride, palladium acetylacetonate, tetrakis(triphenylphosphine)palladium and palladium black, or a mixture of several of them.

[0016] Preferably, the amount of the noble metal palladium compound in S1 is 0.12-12 g, the metal palladium content in the noble metal palladium compound is 1-99.95%, the amount of aqua regia in S1 is 8-20 ml, and the amount of hydrochloric acid in S1 is 18-20 ml.

[0017] Preferably, the molar ratio of sodium borate added during the preparation of the noble metal palladium compound solution to be detected in S1 to the palladium element in the noble metal palladium compound is 1-1.2:1, and the concentration of the boric acid solution in S1 is 1%-5%.

[0018] Preferably, the timing of adding sodium borate in S1 is when the residual nitrate in the solution is completely decomposed, and the vapor is detected using nitric acid test paper without the test paper changing color.

[0019] Preferably, the temperature of the electric heating plate in S1 is 70-90 degrees.

[0020] Preferably, the purity of the palladium flakes / powder used in S2 is greater than 99.95%. The amount of palladium flakes / powder used in the preparation of the standard solution is 0.1-0.6 g.

[0021] Preferably, the metal content in the EDX standard working curve drawn by S3 ranges from 200ppm to 6000ppm.

[0022] Preferably, when the concentration of the element to be detected during the S3 detection process is greater than the highest concentration point of the EDX standard working curve, the solution of the noble metal palladium compound to be detected is diluted with a boric acid solution to within the concentration range of the standard curve before the detection is performed.

[0023] The invention provides a method for detecting the content of metal palladium in a noble metal palladium compound, wherein the noble metal compound comprises a palladium compound, and the palladium metal content of the palladium compound is greater than 1%. The key to the method lies in the preparation of each test solution of the standard solution and the selection of the metal element concentration range in the standard solution working curve; the method sample preparation method is to add sodium borate to the standard sample and the test sample, and the molar ratio of the amount of sodium borate to the amount of palladium is 1-1.2:1; low-temperature evaporation to near dryness, driving away free chlorine, and using a boric acid solution for weighing, and the concentration of the boric acid solution is 1%-5%; the method prepares the standard working curve metal concentration range of 200ppm-6000ppm.

[0024] The preparation method of the present invention can make the matrix of the solution to be detected uniform and stable, and reduce the matrix effect; the standard working curve can achieve precise detection and high accuracy within the optimal metal concentration range, the method is simple and efficient, and different types of palladium compound samples are selected for testing, with excellent detection effect and a wide range of applications. In addition, the interference of chlorine on palladium can be effectively avoided by optimizing the standard sample preparation method, thereby improving the advantages of EDX in the rapid and high-precision detection method of precious metal palladium. DETAILED DESCRIPTION

[0025] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. These descriptions are only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention.

[0026] Example 1 Detection of palladium content in precious metal palladium compounds

[0027] Preparation of the test solution of precious metal palladium compound metal element: palladium chloride solid powder (sample 1), 0.2500g (ten thousandth balance), transferred to a beaker, added 8ml of aqua regia (hydrochloric acid / nitric acid = 3:1), the beaker was transferred to an electric heating plate, the temperature was set to 90 degrees, the solid was completely dissolved, the liquid was concentrated to near dryness, 18ml of hydrochloric acid was added after cooling, 0.28g of sodium borate was added after the yellow smoke completely disappeared, and it was evaporated at low temperature to near dryness. After cooling, boric acid solution (3%) was added and the weight was adjusted to 50.0000g to obtain the test solution.

[0028] Preparation of palladium standard solution: Take 0.5000g of palladium powder (ten thousandth balance), transfer to a beaker, add 18ml of aqua regia (hydrochloric acid / nitric acid = 3:1), transfer the beaker to an electric heating plate, set the temperature to 90 degrees, wait for the palladium powder to completely dissolve, the liquid is concentrated to nearly dry, add 20ml of hydrochloric acid after cooling, add 0.95g of sodium borate after the yellow smoke completely disappears, evaporate at low temperature to nearly dry, add boric acid solution (3%) after cooling, and weigh to 50.0000g. Obtain standard stock solution A; take 1g, 2g, 4g, 8g, 15g, 30g from standard stock solution A respectively, add boric acid solution to weigh to 50.0000g, and obtain 6 groups of standard solutions for drawing EDX standard working curve, the metal content range of the standard working curve is: 200ppm-6000ppm.

[0029] Prepare the test solution and standard solution according to the above method, and use instrumental analysis method to test the test solution.

[0030] The preferred instrumental analysis method is energy-saving X-ray fluorescence emission spectroscopy (EDX for short); the detection process is: prepare standard solutions of precious metal palladium, and six standard solutions with palladium concentrations of 200ppm, 400ppm, 800ppm, 1600ppm, 3000ppm and 6000ppm, respectively. Draw the EDX standard working curve based on this, and when the palladium concentration in the sample solution is greater than the highest concentration point of the standard curve, take the sample solution and dilute it with boric acid solution to the concentration range of the standard curve before measuring.

[0031] The EDX parameters are: collimator 10 mm, atmosphere, air, sample cup is Mylar film, voltage 50 kv, current 100 uA, energy line PdKa is 21 keV, energy range 21-22 keV, integration time 100 s, DT 30%, and quantitative method is integration.

[0032] Example 2

[0033] Preparation of precious metal palladium compound metal element detection liquid: palladium acetate solid powder (sample 2), 0.5000g (ten thousandth balance), transfer to a beaker, add 14ml aqua regia (hydrochloric acid / nitric acid = 3:1), transfer the beaker to an electric heating plate, set the temperature to 80 degrees, wait until the solid is completely dissolved, concentrate the liquid to nearly dry, add 20ml hydrochloric acid after cooling, add 0.45g sodium borate after the yellow smoke completely disappears, evaporate at low temperature to nearly dry, add boric acid solution (3%) after cooling, and weigh to 50.0000g. Get the solution to be tested.

[0034] The palladium content was detected by EDX, the metal prepared by the standard solution was replaced with a palladium sheet, and the rest was carried out according to the method in Example 1. The EDX detection parameters were carried out according to the method in Example 1, which will not be repeated here.

[0035] Example 3

[0036] Preparation of precious metal palladium compound metal element detection solution: palladium acetate solid / palladium chloride powder mixture (sample 3), sample 1 and sample 2 are mixed at a mass ratio of 1:1), weigh 0.2500g (ten thousandth balance), transfer to a beaker, add 12ml aqua regia (hydrochloric acid / nitric acid = 3:1), transfer the beaker to an electric heating plate, set the temperature to 90 degrees, wait until the solid is completely dissolved, the liquid is concentrated to nearly dry, add 18ml hydrochloric acid after cooling, add 0.3g sodium borate after the yellow smoke completely disappears, evaporate at low temperature to nearly dry, add boric acid solution (3%) after cooling, and weigh to 50.0000g. Get the solution to be tested.

[0037] The palladium content was detected by EDX. The standard solution was prepared according to the method in Example 1. The EDX detection parameters were carried out according to the method in Example 1, which will not be repeated here.

[0038] Example 4

[0039] Preparation of precious metal palladium compound metal element detection solution: 1.000g (ten thousandths balance) of tetraammine palladium sulfate solution (sample 4) is transferred to a beaker, and 10ml of aqua regia (hydrochloric acid / nitric acid = 3:1) is added. The beaker is transferred to an electric heating plate, and the temperature is set to 90 degrees. The liquid is concentrated to nearly dryness, and 20ml of hydrochloric acid is added after cooling. After the yellow smoke disappears completely, 0.19g of sodium borate is added, and evaporated at low temperature to nearly dryness. After cooling, boric acid solution (5%) is added, and the weight is fixed to 50.0000g. The solution to be tested is obtained.

[0040] The palladium content was detected by EDX. The standard solution was prepared according to the method in Example 1. The EDX detection parameters were carried out according to the method in Example 1, which will not be repeated here.

[0041] Example 5

[0042] Preparation of precious metal palladium compound metal element detection solution: Palladium black (sample 5), 0.2g (ten thousandths balance), transfer to a beaker, add 10ml aqua regia (hydrochloric acid / nitric acid = 3:1), transfer the beaker to an electric heating plate, set the temperature to 90 degrees, wait until the solid is completely dissolved, concentrate the liquid to nearly dry, add 20ml hydrochloric acid after cooling, add 0.46g sodium borate after the yellow smoke completely disappears, evaporate at low temperature to nearly dry, add boric acid solution (5%) after cooling, and weigh to 50.0000g. Get the solution to be tested.

[0043] The palladium content was detected by EDX. The standard solution was prepared according to the method in Example 1. The EDX detection parameters were carried out according to the method in Example 1. No further details will be given here.

[0044] In summary, the detection results of the palladium content of the above 5 embodiments are as follows:

[0045] Table 1 Example 1-5 Palladium compound palladium content test results data table (%)

[0046] element Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 palladium 59.50％ 47.39％ 53.44％ 1.00％ 99.90％

[0047] Example 6 Precision Evaluation

[0048] The sample test solution preparation and element content determination were repeated 8 times in Example 1. The average value and relative standard deviation (RSD) of the 8 measurement results were statistically calculated to evaluate the detection precision level of the method. The results are shown in Table 2.

[0049] Table 2 Sample 1 precision test data table

[0050]

[0051] Example 7 Precision Evaluation

[0052] The sample test solution preparation and element content determination were repeated 8 times in Example 2. The average value and relative standard deviation (RSD) of the 8 measurement results were calculated to evaluate the detection precision level of the method. The results are shown in Table 3.

[0053] Table 3 Sample 2 precision test data table

[0054]

[0055] When the palladium content detected by EDX was greater than 47%, the RSD was less than 0.11%, indicating that the repeated determination results were consistent, the method had good repeatability, and the method had a high level of precision.

[0056] Example 8 Accuracy Assessment

[0057] Sample 2, sample 4, and sample 5 were subjected to a spike recovery test to obtain the palladium content in the samples from Examples 2, 4, and 5; palladium standard solutions of palladium elements of corresponding concentrations were added to Sample 2, Sample 4, and Sample 5, respectively, and all the operation processes were repeated in the manner of Examples 2, 4, and 5, respectively, and the accuracy of the detection method was evaluated by the palladium recovery rate. The test results are shown in Table 4;

[0058] Table 4 Recovery test data Table 4

[0059] sample Test value before spike Added amount Spiked test value Recovery rate Sample 2 47.40％ 25.00％ 72.18％ 99.70％ Sample 4 1.00％ 1.00％ 2.01％ 100.05％ Sample 5 99.90％ 0.05％ 100.05％ 100.10％

[0060] The recovery rate in Table 4 is 99.70-100.10%, and the test results are highly accurate and reliable.

[0061] Example 9 Comparison of EDX and Gravimetric Methods

[0062] The experiment was repeated 8 times for Example 1, and the palladium content was detected by EDX and the palladium content was detected by gravimetric method. The average value and relative standard deviation (RSD) of the 8 measurement results were calculated respectively to evaluate the consistency of the two methods. See Table 5.

[0063] Table 5 EDX and gravimetric method comparison experimental data

[0064] EDX(%) Weight method (%) 59.50％ 59.65％ 59.53％ 59.45％ 59.45％ 59.38％ 59.55％ 59.40％ 59.60％ 59.30％ 59.45％ 59.38％ 59.48％ 59.59％ 59.40％ 59.25％

[0065] Table 6 One-way ANOVA analysis of the data in Table 5

[0066]

[0067] Table 6 shows that the EDX test results are consistent with the gravimetric test results.

[0068] The above embodiments are only used to help understand the method of the present invention and its main ideas, and do not limit the present application in any form. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the above-disclosed technical content to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for detecting the content of palladium in a noble metal palladium compound, characterized in that: The following steps are included: S1 Pretreatment of precious metal palladium compound: transfer the precious metal palladium compound into a beaker, add aqua regia, and transfer to an electric heating plate for nitrolysis; After the nitration is completed, hydrochloric acid is added to decompose the residual nitrate. After the nitrate is completely decomposed, sodium borate is added and evaporated at low temperature to a nearly dry state to completely remove free chlorine. After cooling, dissolve it with boric acid solution, transfer it to a volumetric flask for weighing, and obtain a solution of precious metal palladium compound to be tested; Preparation method of S2 noble metal standard solution: transfer palladium sheet / powder into a beaker, add aqua regia, and transfer to an electric heating plate for nitrolysis; After the nitration is completed, hydrochloric acid is added to decompose the residual nitrate. After the nitrate is completely nitrated, sodium borate is added and evaporated at low temperature to a nearly dry state to completely remove free chlorine. After cooling, dissolve it with boric acid solution, transfer it to a volumetric flask for weighing, and obtain a noble metal standard solution. Transfer the noble metal standard solution to a volumetric flask for weighing, and after gradual dilution, six standard solutions with different metal contents can be obtained respectively; S3 precision instrument analysis method for detection: The precision instrument analysis method is energy-based X-ray fluorescence emission spectroscopy, and the detection steps are as follows: According to the preparation method in S2, six noble metal standard solutions with palladium concentrations of 200 ppm, 400 ppm, 800 ppm, 1600 ppm, 3000 ppm and 6000 ppm were prepared respectively, and an EDX standard working curve was drawn using the prepared noble metal standard solutions at different concentrations; The detection parameters of the energy-type X-ray fluorescence emission spectrometry are set as follows: collimator 10mm, atmosphere-air, sample cup-Mylar film, voltage 50kv, current 100uA, energy line PdKa is 21keV, energy range 21-22keV, integration time 100s, DT30%, and quantitative method is integration.

2. The method for detecting the palladium content in a noble metal palladium compound according to claim 1, wherein: The noble metal palladium compound includes but is not limited to chloropalladic acid, sodium chloropalladate, palladium chloride, palladium sulfate, palladium nitrate, tetraamminepalladium sulfate, palladium acetate, trimethylpalladium acetate, dichlorotetraamminepalladium, dichlorodiamminepalladium, palladium hydroxide, 1,2-bis(diphenylphosphine)ethanepalladium chloride, palladium acetylacetonate, tetrakis(triphenylphosphine)palladium and palladium black, or a mixture of several of them.

3. The method for detecting the content of palladium in a noble metal palladium compound according to claim 1, wherein: The amount of the noble metal palladium compound in S1 is 0.12-12 g, the metal palladium content in the noble metal palladium compound is 1-99.95%, the amount of aqua regia in S1 is 8-20 ml, and the amount of hydrochloric acid in S1 is 18-20 ml.

4. The method for detecting the content of palladium in a noble metal palladium compound according to claim 1, wherein: The solution of the noble metal palladium compound to be tested in S1 is prepared, the molar ratio of the sodium borate added during the preparation of the noble metal standard solution S2 to the palladium element in the noble metal palladium compound is 1-1.2:1, and the concentration of the boric acid solution in S1 is 1%-5%.

5. The method for detecting the content of palladium in a noble metal palladium compound according to claim 1, wherein: The timing of adding sodium borate to S1 and S2 is when the residual nitrate in the solution is completely decomposed, and the solution vapor is detected using nitric acid test paper, and the nitric acid test paper does not change color.

6. The method for detecting the content of palladium in a noble metal palladium compound according to claim 1, wherein: The temperature of the electric heating plates in S1 and S2 is 70-90 degrees.

7. The method for detecting the content of palladium in a noble metal palladium compound according to claim 1, characterized in that: The purity of the palladium sheet / powder used in S2 is greater than 99.95%.

8. The method for detecting the content of palladium in a noble metal palladium compound according to claim 1, characterized in that: The metal content range in the EDX standard working curve drawn by S3 is 200ppm-6000ppm.

9. The method for detecting the content of palladium in a noble metal palladium compound according to claim 1, characterized in that: During the S3 detection process, when the concentration of the element to be detected is greater than the highest concentration point of the EDX standard working curve, the solution of the noble metal palladium compound to be detected is diluted with a boric acid solution to a concentration range of the standard curve before the detection is performed.

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