An ICP method for determining the content of impurity elements in iron oxide

Abstract

The invention relates to an ICP method for determining the content of impurity elements in iron oxide, which belongs to the technical field of instrumental analysis and testing. It solves the problem that the prior art cannot determine the content of impurity elements in high-purity iron oxide with an iron oxide content of more than 99.99%; it can only determine fourteen elements, namely, sodium, aluminum, phosphorus, sulfur, silicon, boron, chromium, copper, nickel, titanium, calcium, magnesium, manganese, and potassium, and cannot determine zinc and lead, which are common important impurity elements in iron oxide; and the characteristic ICP absorption peaks of the impurity elements interfere with each other, causing interference to the measurement results. The ICP method for determining the content of impurity elements in iron oxide of the invention has an iron oxide content of more than 98.5%, and the specific steps include: grouping the impurity elements; configuring a standard solution of the impurity elements in the groups, and no iron oxide matrix is ​​added to the standard solution. The determination of the content of impurity elements in an iron oxide sample with a purity higher than 99.9% is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic analytical chemistry, and in particular to an ICP method for determining the content of impurity elements in iron oxide. Background Art

[0002] The methods for determining the content of sodium, aluminum, phosphorus, sulfur, silicon, boron, chromium, copper, nickel, lead, titanium, zinc, calcium, magnesium, manganese and potassium in iron oxides all adopt the methods provided in GB / T 24244-2009. In the prior art, when establishing the standard curve of sodium, aluminum, phosphorus, sulfur, silicon, boron, chromium, copper, nickel, lead, titanium, zinc, calcium, magnesium, manganese and potassium standard solutions for determination, considering the influence of iron, the purchased spectrally pure iron oxide is added to the standard solution of the above elements, so that the standard solution and the sample to be tested both contain iron as a background element. However, the prior art provided by the national standard has the following technical problems: (1) ferrite uses iron oxide, and for the detection of impurity elements therein, a standard curve needs to be established. In order to determine the standard curve, in the process of configuring the standard solution of impurity elements with different concentration gradients, spectrally pure iron oxide needs to be used as the matrix, which is complicated to operate; (2) the linearity of the sodium and potassium impurity element marking lines is poor, and the detection error is large; (3) it is not suitable for detecting iron oxide samples with a purity higher than spectrally pure.

[0003] Patent CN 104062280A discloses a method for determining the contents of six impurity elements, manganese, phosphorus, arsenic, lead, zinc, and copper, in a permanent ferrite mixture. A series of standard solution curves are established by acid dissolution. The method uses a combination of hydrochloric acid and nitric acid to treat the sample at about 70°C. It can be seen that the method requires the use of a large amount of acid and can only achieve the measurement of six impurity elements, manganese, phosphorus, arsenic, lead, zinc, and copper. Patent CN104048951A discloses a method for determining the contents of silicon, calcium, and aluminum in permanent ferrite additives and co-solvents by ICP emission spectroscopy. The standard solution is prepared and the standard curve is established by a combination of acid dissolution and alkali dissolution at 75°C-100°C. The operation is cumbersome and a large amount of acid and alkali are also required. More importantly, the above two patents are improvements on the existing Chinese standard measurement method, but the same as the national standard is that both use the addition of spectrally pure iron oxide matrix to the standard solution of the impurity elements. Therefore, both cannot overcome the above problems existing in the national standard method. Summary of the invention

[0004] In view of the above analysis, the present invention aims to provide an ICP method for determining the content of impurity elements in iron oxide, which solves at least one of the following technical problems: (1) It is impossible to determine the content of impurity elements in high-purity iron oxide with an iron oxide content of more than 99.99%; (2) Only fourteen elements, namely sodium, aluminum, phosphorus, sulfur, silicon, boron, chromium, copper, nickel, titanium, calcium, magnesium, manganese and potassium, can be determined, and it is impossible to determine zinc and lead, which are common important impurity elements in iron oxide; (3) The characteristic ICP absorption peaks of the impurity elements interfere with each other, causing interference with the measurement results; (4) It is necessary to add a spectrally pure iron oxide matrix to the standard solution of the impurity elements to establish a standard curve.

[0005] The present invention provides an ICP method for determining the content of impurity elements in iron oxide, wherein the iron oxide content in the iron oxide is above 98.5%, and the specific steps include:

[0006] Step 1. Group the impurity elements;

[0007] Step 2. Prepare standard solutions of impurity elements in groups, wherein no iron oxide matrix is ​​added to the standard solutions.

[0008] Furthermore, the iron oxide content in the iron oxide is above 99.9%.

[0009] Furthermore, the impurity elements include one or more of sodium, aluminum, phosphorus, sulfur, silicon, boron, chromium, copper, nickel, lead, titanium, zinc, calcium, magnesium, manganese, and potassium.

[0010] Furthermore, the impurity elements include at least two groups, in which sodium is a single group, zinc is not in the same group with copper and nickel, magnesium is not in the same group with copper and nickel, and titanium is not in the same group with manganese; the elements in each group are mixed and configured in the same standard solution to obtain a first group of standard solutions, a second group of standard solutions, a third group of standard solutions and a fourth group of standard solutions, respectively.

[0011] Furthermore, the impurity elements are divided into four groups, the first group of impurity elements includes sodium; the second group of impurity elements includes one or more of aluminum, zinc, calcium, magnesium, manganese, and potassium; the third group of impurity elements includes one or more of titanium, nickel, copper, and lead; the fourth group of impurity elements includes one or more of silicon, boron, phosphorus, sulfur, and chromium, and the elements in each group are mixed and configured in the same standard solution to obtain the first group of standard solutions, the second group of standard solutions, the third group of standard solutions, and the fourth group of standard solutions, respectively.

[0012] Furthermore, it is characterized in that each group of standard solutions includes five standard solutions with different concentrations, the concentration of each impurity element in each standard solution is the same, and the concentration of each element in the five standard solutions with different concentrations in each group is 0ppm, 0.25ppm-0.5ppm, 0.5ppm-2.5ppm, 1ppm-3ppm, and 3ppm-5ppm, respectively.

[0013] Furthermore, the ICP method for determining the content of impurity elements in iron oxide also includes:

[0014] Step 3. Select and determine the characteristic ICP absorption peak of each impurity element.

[0015] Furthermore, in step 3, the characteristic ICP absorption peak of zinc element is 202.548 nm.

[0016] Furthermore, in step 3, the characteristic ICP absorption peak of the lead element is 220.353 nm.

[0017] Furthermore, in the step 3, the characteristic ICP absorption peak of the aluminum element is 309.271 nm, the characteristic ICP absorption peak of the boron element is 208.959 nm, the characteristic ICP absorption peak of the copper element is 219.958 nm, the characteristic ICP absorption peak of the nickel element is 221.647 nm, the characteristic ICP absorption peak of the calcium element is 393.366 nm, the characteristic ICP absorption peak of the magnesium element is 285.213 nm, the characteristic ICP absorption peak of the manganese element is 293.930 nm, and the characteristic ICP absorption peak of the phosphorus element is 177.495 nm.

[0018] Furthermore, the ICP method for determining the content of impurity elements in iron oxide also includes:

[0019] Step 4. Determine and draw a standard curve for each impurity element;

[0020] Step 5. Process the sample to prepare a sample solution to be tested;

[0021] Step 6. Determine the content of each impurity element at the characteristic ICP absorption peak of each element.

[0022] Furthermore, in step 5, the specific operation is: weigh high-purity iron oxide powder into a container, add concentrated hydrochloric acid, seal, heat at a constant temperature to dissolve it, and adjust the volume after the sample is completely dissolved.

[0023] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0024] 1. The prior art adds purchased spectrally pure iron oxide as the background matrix of the standard solution of impurity elements, and processes the spectrally pure iron oxide to a purity of approximately 100%, that is, ignoring the impurities in the added spectrally pure iron oxide. However, the purity of the purchased spectrally pure iron oxide only reaches the spectral analysis standard, and it is not an absolutely pure substance. When the purity of the iron oxide of the sample to be tested is higher than that of the spectrally pure iron oxide, that is, the content of impurities in the purchased spectrally pure iron oxide is close to or even exceeds the content of the spectrally pure iron oxide in the sample to be tested, when the existing national standard method is used for measurement, the addition of impurities in the purchased iron oxide causes a huge error in the standard solution of impurity elements, resulting in inaccurate measurement results. The present invention abandons the prior art of adding purchased spectrally pure iron oxide as a matrix in the preparation of the standard solution of impurity elements, avoids the influence of impurities in the purchased iron oxide on the standard solution of impurity elements, improves the measurement accuracy, and realizes the determination of the content of impurity elements in high-purity iron oxide.

[0025] 2. In the determination of zinc and lead, by analyzing the spectral lines, combining the intensity value, the linearity of the standard curve and the spike recovery, the background concentration during sample detection determined that the characteristic ICP spectral line of zinc was 203.220nm and the characteristic ICP spectral line of lead was 220.353nm, thus achieving the effective determination of the two impurity elements of zinc and lead in iron oxide.

[0026] 3. In the prior art, when determining fourteen impurity elements, when preparing the standard solution of impurity elements, the fourteen elements are divided into nine impurity elements of aluminum, calcium, manganese, titanium, magnesium, sodium, potassium, nickel and copper, and mixed into one group, and the remaining elements are mixed into another group. In this grouping, the element sodium is affected by the remaining elements in the mixed standard solution, and the linearity is poor, and the correlation coefficient can only reach 0.988. The element aluminum is affected by the iron oxide matrix, and the background concentration (BEC) is high, above 0.5ppm, and when the sample is detected, it is mostly negative. In the process of preparing the standard solution of sixteen impurity elements, the impurity elements of the present invention include at least two groups, wherein sodium is a separate group, zinc is not in the same group with copper and nickel, magnesium is not in the same group with copper and nickel, and titanium is not in the same group with manganese. Compared with the national standard grouping of the prior art, it is more scientific, reduces the influence between elements, and effectively eliminates the influence of the influence between impurity elements on the measurement accuracy of the standard solution of impurity elements.

[0027] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0029] Figure 1 The standard curve for determining the impurity element sodium in Example 1;

[0030] Figure 2 This is the standard curve for determining the impurity element aluminum in Example 1;

[0031] Figure 3 The standard curve for determining the impurity element zinc in Example 1;

[0032] Figure 4 The standard curve for determining the impurity element calcium in Example 1;

[0033] Figure 5 The standard curve for determining the impurity element magnesium in Example 1;

[0034] Figure 6 The standard curve for determining the impurity element manganese in Example 1;

[0035] Figure 7 The standard curve for determining the impurity element potassium in Example 1;

[0036] Figure 8 The standard curve for determining the impurity element copper in Example 1;

[0037] Fig. 9 The standard curve for determining the impurity element nickel in Example 1;

[0038] Fig.10 The standard curve for determining the impurity element lead in Example 1;

[0039] Fig.11 This is the standard curve for determining the impurity element titanium in Example 1;

[0040] Fig.12 The standard curve for determining the impurity element phosphorus in Example 1;

[0041] Fig.13 The standard curve for determining the impurity element sulfur in Example 1;

[0042] Fig.14 The standard curve for determining the impurity element silicon in Example 1;

[0043] Fig.15 The standard curve for determining the impurity element boron in Example 1;

[0044] Fig.16 This is the standard curve for determining the impurity element chromium in Example 1. DETAILED DESCRIPTION

[0045] At present, the method for determining the content of impurity elements in iron oxide with an iron oxide content greater than 98% is provided by GB / T 24244-2009, which provides a method for measuring the content of impurity elements of sodium, aluminum, phosphorus, sulfur, silicon, boron, chromium, copper, nickel, lead, titanium, zinc, calcium, magnesium, manganese, and potassium in iron oxide with an iron oxide content of more than 98%. When establishing standard solutions of sodium, aluminum, phosphorus, sulfur, silicon, boron, chromium, copper, nickel, lead, titanium, zinc, calcium, magnesium, manganese, and potassium for standard curve determination, the prior art takes into account the influence of iron and uses externally purchased spectrally pure iron oxide to be added to the standard solution of the above elements, so that both the standard solution and the sample to be tested contain iron as a background element. Since the national standard adds externally purchased spectrally pure iron oxide as the background matrix of the impurity element standard solution, the spectrally pure iron oxide is processed with a purity of approximately 100%, that is, the impurities of the added spectrally pure iron oxide are ignored. However, purchased spectrally pure iron oxide only has a purity that meets spectral analysis standards, and is not an absolutely pure substance. We found in experiments that when the iron oxide purity of the sample to be tested is higher than spectrally pure, that is, the impurity content in the purchased spectrally pure iron oxide is close to or even exceeds the iron oxide content in the sample to be tested, when the existing national standard method is used for measurement, the impurity content in the purchased iron oxide added by the national standard method cannot be ignored, and the impurities have a huge impact, resulting in huge errors in the standard solution of impurity elements, causing huge errors in the measurement results. Therefore, the experiment found that the existing national standard method cannot accurately determine the content of impurity elements in high-purity iron oxide (iron oxide content in iron oxide is more than 99.99%).

[0046] Based on this, the present invention provides an ICP method for determining the content of impurity elements in iron oxide, wherein the iron oxide content in the iron oxide is above 98.5%, and is also applicable to iron oxide with an iron oxide content of above 99.99%, and the specific steps include:

[0047] Step 1. Prepare standard solutions of impurity elements in groups;

[0048] In step 1, no iron oxide matrix is ​​added to the standard solution of the impurity element.

[0049] The existing national standard takes into account the influence of iron when determining the impurity content in iron oxide with an iron oxide content of more than 98%. When preparing the standard curve of the above impurity elements, purchased spectrally pure iron oxide is used as the matrix and added to the standard solution of the above impurity elements, so that both the standard solution and the sample to be tested contain iron as the background element. This method has always been the standard method for measuring iron oxide with an iron oxide content of more than 98.5%, and can achieve the determination of the contents of 16 impurity elements in iron oxide, including sodium, aluminum, phosphorus, sulfur, silicon, boron, chromium, copper, nickel, lead, titanium, zinc, calcium, magnesium, manganese, and potassium.

[0050] However, the test found that when the existing method of the national standard was used to measure high-purity iron oxide with an iron oxide content of more than 98.5%, the national standard method had serious errors. The measurement was seriously unscientific, the spike recovery rate was poor, and the content values ​​of various impurity elements measured were negative. The present invention abandons the measurement method of adding an iron oxide matrix to configure an impurity element standard solution in the prior art, does not add any matrix to the impurity element standard solution, and reduces the error of the impurity element standard curve caused by the introduction of impurity elements by adding a matrix.

[0051] Specifically, the ICP method for determining the content of impurity elements in iron oxide includes one or more of sodium, aluminum, phosphorus, sulfur, silicon, boron, chromium, copper, nickel, lead, titanium, zinc, calcium, magnesium, manganese, and potassium.

[0052] Unlike the prior art which can only measure the contents of fourteen impurity elements, namely sodium, aluminum, phosphorus, sulfur, silicon, boron, chromium, copper, nickel, titanium, calcium, magnesium, manganese and potassium in iron oxide, the present invention can measure the contents of two impurity elements, zinc and lead, on the basis of measuring the above fourteen elements.

[0053] Specifically, in the ICP method for determining the content of impurity elements in iron oxide, the impurity elements include at least two groups, among which sodium is a single group, zinc is not in the same group with copper and nickel, magnesium is not in the same group with copper and nickel, and titanium is not in the same group with manganese; the elements in each group are mixed and configured in the same standard solution to obtain a first group of standard solutions, a second group of standard solutions, a third group of standard solutions and a fourth group of standard solutions, respectively.

[0054] After research, it was found that when preparing the standard solution of impurity elements in the prior art, the fourteen impurity elements of sodium, aluminum, phosphorus, sulfur, silicon, boron, chromium, copper, nickel, titanium, calcium, magnesium, manganese and potassium were divided into two groups, among which nine impurity elements of aluminum, calcium, manganese, titanium, magnesium, sodium, potassium, nickel and copper were mixed together to prepare one group of standard solutions, and the remaining five impurity elements were mixed together to prepare another group of standard solutions. However, after research, it was found that the grouping scheme of the prior art, because the ICP absorption of the impurity element sodium is easily affected by other elements, the prior art groups it with other elements, which is very likely to cause the ICP absorption of other elements to affect the impurity element sodium, so the present invention groups the impurity element sodium into a separate group when preparing the standard solution in groups. The emission intensity of zinc at the spectral line 202.548nm is affected by copper and nickel, so zinc is not in the same group as copper and nickel. At the spectral line of 285.213nm, the emission intensity of magnesium is affected by copper and nickel, so magnesium is not in the same group as copper and nickel. At the spectral line of 336.127nm, titanium is affected by manganese, so titanium is not in the same group as manganese. At the same time, the grouping is determined by comprehensively considering the emission intensity of the elements, which greatly improves the interference between the elements.

[0055] In a possible implementation, the impurity elements are divided into four groups, the first group of impurity elements includes sodium; the second group of impurity elements includes one or more of aluminum, zinc, calcium, magnesium, manganese, and potassium; the third group of impurity elements includes one or more of titanium, nickel, copper, and lead; the fourth group of impurity elements includes one or more of silicon, boron, phosphorus, sulfur, and chromium, and the elements in each group are mixed and configured in the same standard solution to obtain a first group of standard solutions, a second group of standard solutions, a third group of standard solutions, and a fourth group of standard solutions, respectively.

[0056] Specifically, in the ICP method for determining the content of impurity elements in iron oxide, each group of standard solutions includes five standard solutions with different concentrations, the concentration of each impurity element in each standard solution is the same, and the concentration of each element in the five standard solutions with different concentrations in each group is 0ppm, 0.25ppm-0.5ppm, 0.5ppm-2.5ppm, 1ppm-3ppm, 3ppm-5ppm, preferably 0ppm, 0.5ppm, 1ppm, 3ppm, 5ppm.

[0057] It should be noted that the purity of iron oxide is higher than 99.9%. After it is acidified with hydrochloric acid to form a solution (1.000g is dissolved in hydrochloric acid and the volume is fixed to 100mL), the elemental impurity content converted into oxide content is required to be lower than 10ppm, so it is more reasonable to set the standard zone line gradient curve at 5ppm.

[0058] Specifically, the ICP method for determining the content of impurity elements in iron oxide also includes:

[0059] Step 3. Select and determine the characteristic ICP absorption peak of each impurity element.

[0060] The characteristic ICP absorption peaks of elements are usually based on the spectrum lines recommended by GB 24244-200, among which aluminum is at 396.135nm, iron has a strong emission intensity at this wavelength, and is easy to interfere with aluminum, boron is at 182.640nm, sulfur emits signals at this wavelength, copper is at 329.396nm, and is easily interfered by calcium, nickel has a large emission intensity at 221.647nm, which is the best spectrum line, calcium is at 422.673nm, aluminum has a strong signal at this wavelength, and the signal affects the detection results, magnesium is at 285.213nm, the emission signal intensity value is large, the linearity is good and the detection error is small, manganese is at 257.610nm, and the high concentration of iron in the sample has a serious impact on the detection results, phosphorus is at 177.495nm, the emission intensity value is large, the signal response is good, and it is the optimal detection spectrum line.

[0061] Specifically, in step 3, the characteristic ICP absorption peak of zinc element is 202.548 nm.

[0062] It should be noted that zinc analyzed the spectral lines at 203.200nm, 213.856nm, and 202.548nm. At the spectral line 202.548nm, it was less affected by iron, the background concentration was low during sample detection, and the interference peaks next to it were small. At the same time, the linearity of the standard curve and the spike recovery were good, and the optimal spectral line of zinc was determined to be 202.548nm.

[0063] Specifically, in step 3, the characteristic ICP absorption peak of the lead element is 220.353 nm.

[0064] It should be noted that when analyzing the spectral lines of lead at 220.535nm and 216.999nm, the overall spectral line spike recovery rates were all qualified. However, at 220.353nm, the sample intensity was relatively high and the background concentration of this spectral line was low. The optimal spectral line of lead was determined to be 220.353nm.

[0065] Specifically, in step 3, the characteristic ICP absorption peak of aluminum element is 309.271nm, the characteristic ICP absorption peak of boron element is 208.959nm, the characteristic ICP absorption peak of copper element is 219.958nm, the characteristic ICP absorption peak of nickel element is 221.647nm, the characteristic ICP absorption peak of calcium element is 393.366nm, the characteristic ICP absorption peak of magnesium element is 285.213nm, the characteristic ICP absorption peak of manganese element is 293.930nm, and the characteristic ICP absorption peak of phosphorus element is 177.495nm.

[0066] The experiment shows that under this selected spectral line, it can be observed that the detection is less affected by the iron in the sample, the background concentration is low, the linearity is good, and the spike recovery rate is high.

[0067] Specifically, the ICP method for determining the content of impurity elements in iron oxide also includes:

[0068] Step 3. Determine and draw a standard curve for each impurity element;

[0069] Step 4. Processing the sample to prepare a sample solution to be tested;

[0070] Step 5. Determine the content of each impurity element at the characteristic ICP absorption peak of each element.

[0071] Specifically, in step 5, the specific operation is: weigh high-purity iron oxide powder into a container, add concentrated hydrochloric acid, seal, heat at a constant temperature to dissolve it, and adjust the volume after the sample is completely dissolved.

[0072] Specifically, the mass of the high-purity iron powder weighed is 0.5 g to 1 g.

[0073] Specifically, the amount of concentrated hydrochloric acid added is 5.0 mL to 10 mL.

[0074] Specifically, the temperature for constant temperature heating to dissolve the material is 40°C to 60°C.

[0075] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0076] Embodiment 1

[0077] This embodiment discloses an ICP method for determining the content of impurity elements in iron oxide.

[0078] Step 1: Divide the 16 elements in the iron oxide impurities into four groups and prepare standard solutions respectively: the first group of standard solutions: sodium; the second group of standard solutions: aluminum, zinc, calcium, magnesium, manganese, potassium; the third group of standard solutions: copper, nickel, lead, titanium; the fourth group of standard solutions: silicon, boron, phosphorus, sulfur, chromium. Each group of standard solutions includes five standard solutions with concentration gradients: 0ppm, 0.5ppm, 1ppm, 3ppm, 5ppm.

[0079] Step 2: Determine the ICP characteristic absorption peak of the impurity element, as shown in Table 1.

[0080] Step 3, under the grouping conditions of step 1, the spiked recoveries and detection linearity of 16 impurity elements of high-purity iron oxide were determined. The results are shown in Table 1. The standard spectra of the 16 impurity elements are as follows: Figures 1 to 16 shown.

[0081] Step 4: Take 1.000g (±0.0001g) of commercially available high-purity iron oxide (specification 99.99%, number NCS1280, batch 2021-03-29, Gangyan Nake Testing Technology Co., Ltd., standard substance), add 10mL of concentrated hydrochloric acid to a 100mL quartz beaker, cover with a watch glass, and heat at 60°C to dissolve it (about 2-3h). After the sample is completely dissolved, transfer it to a 100mL plastic volumetric flask.

[0082] Step 5, using the marking line obtained in step 3, the test was repeated three times on the ICP equipment. The test results are shown in Table 2.

[0083] Table 1 Linearity and spike recovery test results of 16 impurity elements in standard iron oxide

[0084]

[0085] Table 2 Standard iron oxide test results

[0086]

[0087] The percentage of each element calculated based on the test results is compared with the test results of the standard substance and is shown in Table 3.

[0088] Table 3 Comparison of test results and theoretical values

[0089]

[0090]

[0091] As shown in Table 3, according to the test report provided by the standard substance, the test results of the six impurity elements silicon, manganese, chromium, nickel, copper and aluminum contained in the reference substance are consistent with the actual standard values, where “ / ” in the standard substance test report indicates that the test data is not provided in the quality inspection report.

[0092] Comparative Example 1

[0093] The standard substance of Example 1 was tested using the method of the prior art GB 24244-2009.

[0094] Weigh 10 portions of spectrally pure iron oxide powder (Tianjin Komiou Chemical Reagent Co., Ltd., specification 10g, specification 99.5%), 1.000g each (accurate to 0.001g), transfer them into 10 100mL quartz beakers, add 10mL of concentrated hydrochloric acid, cover with a watch glass, heat at low temperature to dissolve it, and transfer them into 10 100mL plastic volumetric flasks, of which 5 volumetric flasks are added with 100ppm standard solution volume:

[0095] Sodium standard solution: 0mL, 0.40mL, 1.6mL, 2.80mL, 4.00mL;

[0096] Aluminum standard solution: 0mL, 0.40mL, 1.6mL, 2.80mL, 4.00mL;

[0097] Potassium standard solution: 0mL, 0.20mL, 0.80mL, 1.40mL, 2.00mL;

[0098] Copper standard solution: 0mL, 0.20mL, 0.80mL, 1.40mL, 2.00mL;

[0099] Nickel standard solution: 0mL, 0.40mL, 1.60mL, 2.80mL, 4.00mL;

[0100] Lead standard solution: 0mL, 0.40mL, 1.60mL, 2.80mL, 4.00mL;

[0101] Titanium standard solution: 0mL, 0.40mL, 1.60mL, 2.80mL, 4.00mL;

[0102] Zinc standard solution: 0mL, 0.40mL, 1.60mL, 2.80mL, 4.00mL;

[0103] Calcium standard solution: 0mL, 0.40mL, 1.60mL, 2.80mL, 4.00mL;

[0104] Magnesium standard solution: 0mL, 0.40mL, 1.60mL, 2.80mL, 4.00mL;

[0105] Manganese standard solution: 0mL, 1.00mL, 1.50mL, 2.00mL, 2.50mL;

[0106] Add the following to the other 5 volumetric flasks:

[0107] Silicon standard solution: 0mL, 0.20mL, 0.80mL, 1.40mL, 2.00mL;

[0108] Boron standard solution: 0mL, 0.40mL, 1.60mL, 2.80mL, 4.00mL;

[0109] Phosphorus standard solution: 0mL, 0.40mL, 1.60mL, 2.80mL, 4.00mL;

[0110] Sulfur standard solution: 0mL, 0.20mL, 0.80mL, 1.40mL, 2.00mL;

[0111] Chromium standard solution: 0mL, 1.00mL, 1.50mL, 2.00mL, 2.50mL;

[0112] Sample treatment: Take 1.000g (±0.0001g) of commercially available high-purity iron oxide (specification 99.99%, number NCS1280, batch 2021-03-29, Gangyan Nake Testing Technology Co., Ltd.), add 10mL of concentrated hydrochloric acid to a 100mL quartz beaker, cover with a watch glass, and heat at 60°C to dissolve it (about 2-3h). After the sample is completely dissolved, transfer it to a 100mL plastic volumetric flask. At the same time, the solution sample is spiked and recovered, and the results of the ICP test are as follows, see Table 4.

[0113] Table 4 Linearity and spike recovery test results of 16 impurity elements in standard iron oxide according to national standard method

[0114]

[0115] Table 5 Test results of 16 impurity elements in standard iron oxide according to national standard

[0116]

[0117]

[0118] It can be seen from Table 4 and Table 5 that under the above standard solution grouping conditions, the linear correlation coefficient R 2 All of them are above 0.998, but it can be seen that the spiked recoveries of sodium, potassium and silicon in the samples are outside 120%, and the spiked recoveries are poor. At the same time, due to the high content of impurities in spectrally pure iron oxide, the impurity elements in the test results are mostly negative values, among which the impurity elements silicon, potassium and aluminum are particularly prominent, which is obviously not scientific.

[0119] And by observing Table 5, it is found that according to the test report provided by the standard substance, the test results of the six impurity elements silicon, manganese, chromium, nickel, copper and aluminum contained in the reference substance are seriously inconsistent with the actual standard values.

[0120] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. An ICP method for determining the content of impurity elements in iron oxide, characterized in that: The iron oxide content in the iron oxide is above 98.5%, and the specific steps include: Step 1. Group the impurity elements; Step 2. Prepare standard solutions of impurity elements in groups, wherein no spectrally pure iron oxide matrix is ​​added to the standard solutions; Step 3. Select and determine the characteristic ICP absorption peak of each impurity element; Step 4. Determine and draw a standard curve for each impurity element; Step 5. Process the sample to prepare a sample solution to be tested; Step 6. Determine the content of each impurity element at the characteristic ICP absorption peak of each element; The impurity elements include one or more of sodium, aluminum, phosphorus, sulfur, silicon, boron, chromium, copper, nickel, lead, titanium, zinc, calcium, magnesium, manganese, and potassium; The impurity elements include at least two groups, wherein sodium is a separate group, zinc is not in the same group with copper and nickel, magnesium is not in the same group with copper and nickel, and titanium is not in the same group with manganese; the elements in each group are mixed and configured into the same standard solution to obtain the standard solutions of each group; The characteristic ICP absorption peak of aluminum element is 309.271nm; the characteristic ICP absorption peak of boron element is 208.959nm; the characteristic ICP absorption peak of calcium element is 393.366nm.

2. The ICP method for determining the content of impurity elements in iron oxide according to claim 1, characterized in that: The iron oxide content in the iron oxide is above 99.9%.

3. The ICP method for determining the content of impurity elements in iron oxide according to claim 1, characterized in that: Each group of standard solutions includes five standard solutions with different concentrations. The concentration of each impurity element in each standard solution is the same. The concentrations of each element in the five standard solutions with different concentrations in each group are 0ppm, 0.25ppm-0.5ppm, 0.5ppm-2.5ppm, 1ppm-3ppm, and 3ppm-5ppm, respectively.

4. The ICP method for determining the content of impurity elements in iron oxide according to claim 1, characterized in that: In step 3, the characteristic ICP absorption peak of copper element is 219.958 nm.

5. The ICP method for determining the content of impurity elements in iron oxide according to claim 1, characterized in that: In the step 3, the characteristic ICP absorption peak of zinc element is 202.548 nm.

6. The ICP method for determining the content of impurity elements in iron oxide according to claim 1, characterized in that: In step 3, the characteristic ICP absorption peak of the lead element is 220.353 nm.

7. The ICP method for determining the content of impurity elements in iron oxide according to claim 1, characterized in that: In the step 3, the characteristic ICP absorption peak of manganese element is 293.930 nm, and the characteristic ICP absorption peak of phosphorus element is 177.495 nm.

8. The ICP method for determining the content of impurity elements in iron oxide according to claim 7, characterized in that: The characteristic ICP absorption peak of nickel element is 221.647nm.

9. The ICP method for determining the content of impurity elements in iron oxide according to claim 8, characterized in that: The characteristic ICP absorption peak of magnesium is 285.213nm.

10. The ICP method for determining the content of impurity elements in iron oxide according to claim 8, characterized in that: In step 5, the specific operation is: weigh high-purity iron oxide powder into a container, add concentrated hydrochloric acid, seal, heat at a constant temperature to dissolve it, and adjust the volume after the sample is completely dissolved.

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