Method for determining content of impurity elements in concentrated isotope based on HR-ICP-MS

Abstract

The invention provides a method for determining the content of impurity elements in concentrated isotopes based on HR-ICP-MS, and belongs to the technical field of element detection. The method provided by the invention only needs to consume a small amount of concentrated isotope samples, and is especially suitable for accurate analysis of purity of high-value to-be-detected substances such as concentrated isotopes; according to the method, 68 impurity elements can be analyzed at the same time by using a series of element mixed solution standard substances, and the method is obviously superior to an impurity analysis method based on an ICP-MS (Inductively Coupled Plasma Mass Spectrometry) method in the prior art; an improved matrix effect correction method is utilized, and correction of the matrix effect is realized through measurement of sensitivity factors under a to-be-measured matrix; according to the invention, a special sample measurement process is designed, a process blank without a matrix is measured through an external standard method, the impurity content in the sample is measured through matrix matching, and the measurement result is more accurate.

Description

Technical Field

[0001] The invention relates to the technical field of element detection, and in particular to a method for determining the content of impurity elements in concentrated isotopes based on HR-ICP-MS. Background Art

[0002] When the isotope abundance in a material is different from its natural abundance, the enriched isotope material often exhibits special properties, thus having extensive and important applications in frontier physics detection, electronics industry, semiconductors, quantum computing, biomedicine, and other fields. When enriched isotopes are used in the above-mentioned application fields, their chemical purity is one of the two most critical indicators affecting their performance, such as the content of harmful elements in medical enriched isotopes, the content of impurity elements in enriched Si and Ge isotopes used in quantum computing and high-performance chips, and so on. Therefore, an analytical method for accurately determining the content of impurity elements in enriched isotopes is extremely important. Among the existing impurity element analysis methods, glow discharge mass spectrometry (GDMS) can directly analyze all element impurities in solid materials, but it requires the material to be conductive and requires matrix-matched standard substances, which are difficult to achieve for enriched isotopes; neutron activation analysis (NAA) can also perform full element impurity analysis, but it requires irradiation of the sample, and cost, machine time, safety, etc. are the key factors limiting its widespread application; other methods such as ICP-OES, AAS, XRF, etc. can also perform multi-element analysis, but their analysis accuracy, detection limit, spectral interference, etc. have great limitations.

[0003] Compared with the above detection methods, high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) has the advantages of high sensitivity, low detection limit, good precision, wide linear range, high resolution, and simultaneous analysis of multiple elements. At present, high-resolution inductively coupled plasma mass spectrometry has been applied to the purity analysis of samples such as high-purity titanium dioxide, high-purity rare earth compounds, high-purity metals, and high-purity organic reagents. However, in these applications, only some impurity elements (several to twenty or thirty) were analyzed, and there was no mention of simultaneous analysis of 68 impurity elements. There has been no report on the application of HR-ICP-MS to enriched isotope analysis. Summary of the invention

[0004] The object of the present invention is to provide a method for determining the content of impurity elements in enriched isotopes based on HR-ICP-MS. The method provided by the present invention can simultaneously analyze 68 impurity elements using a very small amount of sample, and the measurement results are highly accurate.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for determining the content of impurity elements in enriched isotopes based on HR-ICP-MS, comprising the following steps:

[0007] (1) dissolving the concentrated isotope to be tested in a solvent to obtain a sample to be tested, and dividing the sample into sample 1, sample 2, and sample 3 of equal volume;

[0008] The matrix in the sample to be tested is 2% HNO3;

[0009] Prepare a blank process according to the above preparation process of the sample to be tested, except that no concentrated isotope to be tested is added;

[0010] (2) Using the element mixed solution series standard substances, prepare standard solutions with concentrations of 1 μg / kg, 2 μg / kg, 5 μg / kg and 10 μg / kg, respectively, and record them as std1 to 4;

[0011] Prepare 1 mg / kg element mixed solution standard material as the spiked mother solution, and prepare solutions with spiked concentrations of 20 μg / kg and 50 μg / kg by weighing, which are recorded as std5 and std6 respectively;

[0012] There is no order of precedence between step (1) and step (2);

[0013] (3) using a high-resolution inductively coupled plasma mass spectrometer to measure and analyze sample 1, sample 2, and sample 3 obtained in step (1) and the process blank, as well as std1 to 6 obtained in step (2), to obtain a corresponding working curve;

[0014] The order of measurement is: 2% HNO3, std1, std2, std3, std4, 2% HNO3, process blank, sample 1, sample 2, sample 3, std5, std6;

[0015] (4) calculating the impurity element content in the process blank according to the working curve of std1-4 measured in step (3);

[0016] According to the working curves of samples 1 to 3 and std5 and 6 measured in step (3), the impurity element content in the sample to be measured is calculated using the signal values ​​actually measured for samples 1 to 3 and the sensitivity measured for std5 and 6;

[0017] The difference between the impurity element content in the process blank and the impurity element content in the sample to be tested is divided by the concentration of the concentrated isotope to be tested in the sample to be tested to obtain the impurity element content in the concentrated isotope to be tested.

[0018] Preferably, in step (1), at least one of ultrapure water, pure nitric acid, ammonia water and hydrochloric acid is selected as the solvent according to the different concentrated isotopes to be detected.

[0019] Preferably, the mass of the concentrated isotope to be detected in step (1) is 10 mg, and the concentration of the concentrated isotope to be detected in the sample to be tested is 1000 mg / kg.

[0020] Preferably, the element mixed solution series standard substances in step (2) conform to GBW(E)082428-082431.

[0021] Preferably, in step (3), the nuclide with the highest abundance is selected as the impurity element / ion to be detected.

[0022] Preferably, in step (3), the resolution mode of the measurement and analysis is set according to the resolution required to distinguish the interfering ions of the impurity elements / ions to be measured.

[0023] Preferably, when the required resolution is less than 400, a low-resolution mode is set; when the required resolution is between 400 and 4000, a medium-resolution mode is set; and when the required resolution is greater than 4000, a high-resolution mode is set.

[0024] Preferably, the detection parameters of the high-resolution inductively coupled plasma mass spectrometer in the step (3) are: RF generator power 1250 kW; cooling gas flow rate 16 L / min, auxiliary gas flow rate 0.8-1.0 L / min, nebulizing gas flow rate 0.9-1.2 L / n in; injection rate 0.1-0.2 mL / nin, sampling time 20-100 ms / element; acceleration voltage -2 kV.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. The method provided by the present invention only requires the consumption of a small amount (10 mg) of concentrated isotope sample, and is particularly suitable for accurate analysis of the purity of high-value analytes such as concentrated isotopes;

[0027] 2. The present invention uses a series of standard substances of element mixed solution (in accordance with GBW (E) 082428-082431) to achieve simultaneous analysis of 68 impurity elements, which is significantly better than the impurity analysis method based on ICP-MS method in the prior art;

[0028] 3. The matrix effect will seriously affect the accuracy of the ICP-MS measurement results. The standard addition requires that the spike concentration matches the concentration of the analyte. However, the impurity content in the concentrated isotope is unknown and the concentration varies, making it difficult to measure using the traditional standard addition method. The present invention achieves the correction of the matrix effect by measuring the sensitivity factor under the matrix to be measured through an improved matrix effect correction method.

[0029] 4. The present invention designs a special sample measurement process, measures the process blank without matrix by external standard method, and measures the impurity content in the sample by matrix matching, so that the measurement result is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a statistical diagram of matrix inhibition efficiency of Yb solutions of different concentrations in the present invention;

[0031] Figure 2 It is a statistical diagram of matrix suppression efficiency of 1000 mg / kg Ge solution in the present invention;

[0032] Figure 3 This is a statistical diagram of the matrix inhibition efficiency of 3500 mg / kg Mo solution in the present invention;

[0033] Figure 4 This is a statistical diagram of the matrix inhibition efficiency of 1300 mg / kg Ni solution in the present invention;

[0034] Figure 5 It is a statistical diagram of the matrix inhibition efficiency of 1500 mg / kg Y solution in the present invention;

[0035] Figure 6 It is a statistical diagram of the matrix inhibition efficiency of 1000 mg / kg Zn solution in the present invention. DETAILED DESCRIPTION

[0036] The present invention provides a method for determining the content of impurity elements in enriched isotopes based on HR-ICP-MS, comprising the following steps:

[0037] (1) dissolving the concentrated isotope to be tested in a solvent to obtain a sample to be tested, and dividing the sample into sample 1, sample 2, and sample 3 of equal volume;

[0038] The matrix in the sample to be tested is 2% HNO3;

[0039] Prepare a blank process according to the above preparation process of the sample to be tested, except that no concentrated isotope to be tested is added;

[0040] (2) Using the element mixed solution series standard substances, prepare standard solutions with concentrations of 1 μg / kg, 2 μg / kg, 5 μg / kg and 10 μg / kg, respectively, and record them as std1 to 4;

[0041] Prepare 1 mg / kg element mixed solution standard material as the spiked mother solution, and prepare solutions with spiked concentrations of 20 μg / kg and 50 μg / kg by weighing, which are recorded as std5 and std6 respectively;

[0042] There is no order of precedence between step (1) and step (2);

[0043] (3) using a high-resolution inductively coupled plasma mass spectrometer to measure and analyze sample 1, sample 2, and sample 3 obtained in step (1) and the process blank, as well as std1 to 6 obtained in step (2), to obtain a corresponding working curve;

[0044] The order of measurement is: 2% HNO3, std1, std2, std3, std4, 2% HNO3, process blank, sample 1, sample 2, sample 3, std5, std6;

[0045] (4) calculating the impurity element content in the process blank according to the working curve of std1-4 measured in step (3);

[0046] According to the working curves of samples 1 to 3 and std5 and 6 measured in step (3), the impurity element content in the sample to be measured is calculated using the signal values ​​actually measured for samples 1 to 3 and the sensitivity measured for std5 and 6;

[0047] The difference between the impurity element content in the process blank and the impurity element content in the sample to be tested is divided by the concentration of the concentrated isotope to be tested in the sample to be tested to obtain the impurity element content in the concentrated isotope to be tested.

[0048] The present invention dissolves the concentrated isotope to be tested in a solvent to obtain a sample to be tested, and divides the sample into sample 1, sample 2 and sample 3 of equal volumes.

[0049] In the present invention, the enriched isotope to be measured preferably includes at least one of Li, B, Mg, Si, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Se, Rb, Sr, Y, Zr, Nb, Mo, Rh, Pd, Ag, Cd, Sn, Sb, Te, Ba, rare earth elements, Hf, Ta, W, Re, Os, Ir, Pt, Hg, Pb, and U.

[0050] In the present invention, at least one of ultrapure water, nitric acid, ammonia water and hydrochloric acid is preferably used as the solvent according to the different concentrated isotopes to be detected.

[0051] In the present invention, the mass of the concentrated isotope to be detected is preferably 10 mg, and the concentration of the concentrated isotope to be detected in the sample to be detected is preferably 1000 mg / kg.

[0052] The present invention follows the above-mentioned preparation process of the sample to be tested, except that no concentrated isotope to be tested is added, and the preparation process is blank.

[0053] The present invention utilizes the process blank for background subtraction of the sample to be tested.

[0054] The present invention uses a series of element mixed solution standard substances to prepare standard solutions with concentrations of 1 μg / kg, 2 μg / kg, 5 μg / kg and 10 μg / kg, which are respectively recorded as std1-4; 1 mg / kg of element mixed solution standard substance is prepared as a spiked mother solution, and solutions with spiked concentrations of 20 μg / kg and 50 μg / kg are prepared by weighing, which are respectively recorded as std5 and std6.

[0055] In the present invention, there is no particular order in which the test sample and std1-6 are prepared.

[0056] In the present invention, the element mixed solution series standard substances preferably comply with GBW(E)082428-082431.

[0057] In the present invention, the standard substances are prepared by using a series of standard substances of element mixed solutions conforming to GBW(E)082428-082431, so that the simultaneous analysis of 68 impurity elements can be achieved.

[0058] The present invention uses a high-resolution inductively coupled plasma mass spectrometer to measure and analyze the sample 1, sample 2, sample 3, process blank, and std1 to 6 to obtain a corresponding working curve;

[0059] The measurement sequence is: 2% HNO3, std1, std2, std3, std4, 2% HNO3, process blank, sample 1, sample 2, sample 3, std5, std6.

[0060] The present invention sets the order of the above measurements to avoid the influence of the sample matrix on the process blank measurement and the influence of the added standard on the sample measurement, so that the measurement can be carried out continuously, the cleaning time is reduced, and the measurement efficiency is improved.

[0061] In the present invention, before the measurement and analysis, it is preferred to replace the cleaned nickel cone to reduce the background interference of the instrument, and use a 1 ng / g mixed standard solution (GBW(E)130242) to tune the sensitivity and resolution of the instrument so that the In count under low resolution is more than 1 million, the resolution of the medium resolution mode is better than 4000, and the resolution of the high resolution mode is better than 9000.

[0062] In the present invention, the nuclide with the highest abundance is preferably selected as the impurity element / ion to be detected.

[0063] In the present invention, the resolution mode of the measurement and analysis is preferably set according to the resolution required to distinguish the interfering ions of the impurity elements / ions to be measured.

[0064] In the present invention, when the required resolution is less than 400, it is preferred to set the low-resolution mode; when the required resolution is 400-4000, it is preferred to set the medium-resolution mode; when the required resolution is greater than 4000, it is preferred to set the high-resolution mode.

[0065] In the present invention, when measuring the analysis flow blank and std1 to 6, it is preferred to set the same resolution mode as that of samples 1 to 3.

[0066] In the present invention, the detection parameters of the high-resolution inductively coupled plasma mass spectrometer are preferably: RF generator power 1250kW; cooling gas flow rate 16L / min, auxiliary gas flow rate 0.8-1.0L / min, nebulizing gas flow rate 0.9-1.2L / nin; injection rate 0.1-0.2mL / nin, sampling time 20-100ms / element; acceleration voltage -2kV.

[0067] After obtaining the corresponding working curve, the present invention calculates the content of impurity elements in the process blank according to the measured working curve of std1-4, and calculates the content of impurity elements in the sample to be tested according to the measured working curve of samples 1-3 and std5, 6 using the signal values ​​actually measured for samples 1-3 and the sensitivity obtained by measuring std5, 6; the difference between the content of impurity elements in the process blank and the content of impurity elements in the sample to be tested is divided by the concentration of the concentrated isotope to be tested in the sample to be tested to obtain the content of impurity elements in the concentrated isotope to be tested.

[0068] The present invention adopts a new matrix effect correction method, sets the process blank and the sample to be measured using different measurement modes, and significantly improves the accuracy of the measurement result.

[0069] The present invention only requires 10 mg of sample and is particularly suitable for the analysis of high-value samples such as concentrated isotopes; through the combined use of low, medium and high resolution modes, different elements to be measured and their interfering ions can be completely separated, and simultaneous detection can be achieved; through the use of existing multi-element mixed standard solutions GBW (E) 082428-082431, the accuracy and traceability of the measurement results can be guaranteed; the matrix effect can be overcome by using methods such as the standard addition method to achieve accurate measurement.

[0070] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0071] Example 1 of the present invention 176 Yb enriched isotope samples were purchased from the market.

[0072] Example 1

[0073] A method for determining the content of impurity elements in enriched isotopes based on HR-ICP-MS, the steps are as follows:

[0074] (1) Use a high-precision balance (Mettler-Toledo, 0.01 mg) to accurately weigh 10 mg 176 The Yb concentrated isotope sample was placed in a clean PFA tank, 1 mL of ultrapure water and 0.2 mL of concentrated nitric acid were added, and the sample was heated to dissolve. Finally, the sample was fixed to volume with ultrapure water to obtain 176 The concentration of Yb enriched isotope is 1000 mg / kg of the sample to be tested;

[0075] The matrix in the sample to be tested is 2% HNO3;

[0076] According to the preparation process of the sample to be tested, except that no concentrated isotope to be tested is added and a process blank is prepared, all the processing procedures are consistent with the sample to be tested. The process blank is used for sample background subtraction;

[0077] (2) Using element mixed solution series standard substances (in accordance with GBW (E) 082428-082431), standard solutions with concentrations of 1 μg / kg, 2 μg / kg, 5 μg / kg and 10 μg / kg were prepared, which were recorded as std1-4 respectively; at the same time, 1 mg / kg of element mixed solution standard substances were prepared as spiked mother solution, and solutions with spiked concentrations of 20 μg / kg and 50 μg / kg were prepared by weighing, which were recorded as std5 and std6 respectively, for matrix effect correction;

[0078] There is no order of precedence between step (1) and step (2);

[0079] (3) using a high-resolution inductively coupled plasma mass spectrometer to measure and analyze sample 1, sample 2, and sample 3 obtained in step (1) and the process blank, as well as std1 to 6 obtained in step (2), to obtain a corresponding working curve;

[0080] Select the nuclide with the highest abundance as the impurity element / ion to be measured; set the resolution mode of the measurement and analysis according to the resolution energy required to distinguish the interfering ions of the impurity element / ion to be measured, specifically: when the resolution energy is less than 400, set the low resolution mode; when the resolution energy is 400-4000, set the medium resolution mode MR; when the resolution energy is greater than 4000, set the high resolution mode HR; when measuring the blank and std1-6 of the analysis process, set the same resolution mode as samples 1-3;

[0081] 176 The mass number of each element measured (i.e., the impurity element to be measured) and the resolution used in the measurement of Yb enriched isotope are shown in Table 1.

[0082] Table 1. 176 The mass number of each element and the resolution mode used in the measurement of Yb enriched isotope

[0083]

[0084]

[0085] Before the measurement and analysis, a clean nickel cone was replaced to reduce the background interference of the instrument, and a 1 ng / g mixed standard solution (GBW (E) 130242) was used to tune the sensitivity and resolution of the instrument so that the count of In at low resolution was more than 1 million, the resolution of the medium resolution mode was better than 4000, and the resolution of the high resolution mode was better than 9000. The optimized HR-ICP-MS detection parameters are shown in Table 2.

[0086] Table 2 176 HR-ICP-MS operating parameters for Yb enrichment isotope measurement

[0087]

[0088] Other detection parameters of the high-resolution inductively coupled plasma mass spectrometer are: injection rate 0.1 mL / n in, sampling time 20 ms / element; acceleration voltage -2 kV;

[0089] The order of measurement is: 2% HNO3, std1, std2, std3, std4, 2% HNO3, process blank, sample 1, sample 2, sample 3, std5, std6;

[0090] (4) The content of impurity elements in the process blank is calculated according to the working curve of std1-4 measured in step (3); the content of impurity elements in the sample to be tested is calculated according to the working curve of samples 1 to 3 and std5, 6 measured in step (3) using the signal values ​​actually measured for samples 1 to 3 and the sensitivity (i.e., slope) measured by std5, 6; the content of impurity elements in the sample is obtained by dividing the difference between the content of impurity elements in the process blank and the content of impurity elements in the sample to be tested by the concentration of the prepared sample solution; the final test results are shown in Table 3.

[0091] Table 3 Example 1 Detection 176 Statistics of Yb enriched isotopes

[0092]

[0093] Study 1: The inhibitory effect of matrix effect on impurity measurement results

[0094] In order to study the inhibitory effect of the matrix effect on the impurity measurement results, samples with different concentrations and different matrices were prepared in the same way as in Example 1, and the samples were measured and analyzed using the method in Example 1. The slope of the working curve measured by std1-4 was defined as R1, and the slope measured by std5-6 was defined as R2. The matrix suppression efficiency was defined as The inhibition efficiency of different matrices is detected and calculated as follows: Figures 1 to 6 shown.

[0095] According to the same method as in Example 1, Yb solutions with concentrations of 100 mg / kg, 500 mg / kg, 600 mg / kg, 1000 mg / kg, 2000 mg / kg, 3000 mg / kg, and 4000 mg / kg were measured and analyzed to obtain a statistical graph of matrix inhibition efficiency of Yb solutions with different concentrations as shown in FIG. Figure 1 As shown. Figure 1 It can be seen that for Yb, the higher the matrix concentration, the stronger the matrix suppression effect. The strength of the suppression is related to the element. If no method is found to overcome it, it will significantly affect the accuracy of the measurement results.

[0096] According to the same method as in Example 1, a Ge solution with a concentration of 1000 mg / kg was measured and analyzed to obtain a statistical graph of the matrix suppression efficiency of the Ge solution with a concentration of 1000 mg / kg. Figure 2 As shown. Figure 2 It can be seen that the Ge matrix has a significant suppression effect on the signals of other impurity elements. The strength of the suppression is related to the element. If it is not corrected, it will affect the accuracy of the measurement results.

[0097] According to the same method as in Example 1, the 3500 mg / kg Mo solution was measured and analyzed to obtain the matrix inhibition efficiency statistics of the 3500 mg / kg Mo solution as shown in the figure: Figure 3 As shown. Figure 3 It can be seen that the Mo matrix has a significant inhibitory effect on the signals of other impurity elements. The intensity of the inhibition is related to the element. If it is not corrected, the accuracy of the measurement results will be affected.

[0098] According to the same method as in Example 1, the 1300 mg / kg Ni solution was measured and analyzed to obtain the matrix inhibition efficiency statistics of the 1300 mg / kg Ni solution as shown in the figure: Figure 4 As shown. Figure 4 It can be seen that the Ni matrix has a significant inhibitory effect on the signals of other impurity elements. The intensity of the inhibition is related to the element. If it is not corrected, the accuracy of the measurement results will be affected.

[0099] According to the same method as in Example 1, the Y solution of 1500 mg / kg was measured and analyzed to obtain the matrix inhibition efficiency statistics of the Y solution of 1500 mg / kg as shown in the figure: Figure 5 As shown. Figure 5 It can be seen that the Y matrix has a significant inhibitory effect on the signals of other impurity elements. The intensity of the inhibition is related to the element. If it is not corrected, the accuracy of the measurement results will be affected.

[0100] According to the same method as in Example 1, a 1000 mg / kg Zn solution was measured and analyzed to obtain a statistical graph of the matrix inhibition efficiency of the 1000 mg / kg Zn solution as shown in FIG. Figure 6 As shown. Figure 6 It can be seen that the Zn matrix has a significant inhibitory effect on most impurity element signals. The intensity of the inhibition is related to the element. If it is not corrected, the accuracy of the measurement results will be affected.

[0101] In summary, it can be seen that the matrix effect is inconsistent for different elements; for the same element, the matrix effect increases with the increase of matrix concentration; under the same matrix, the matrix suppression effect of different elements is also slightly different.

[0102] Research 2: Spike recovery experiment

[0103] In order to verify the detection effect of the method provided by the present invention on 68 impurity elements, taking a high-purity ytterbium oxide sample as an example, a solution with a concentration of 500 μg / g and a mixed standard solution of 68 impurity elements added with 10 ng / g was prepared as a sample solution to be tested, and the impurity element contents in the solution before and after the addition of the spike were measured by the external standard method (as a comparative example) and the method of Example 1 of the present invention (i.e., the matrix matching method, as Example 2), and the calculated recovery rate is shown in Table 3.

[0104] The external standard method is used for measurement, and the specific steps are as follows: use element mixed solution series standard substances (in accordance with GBW (E) 082428 ~ 082431) to prepare standard solutions with concentrations of 1μg / kg, 2μg / kg, 5μg / kg and 10μg / kg, respectively, and record them as std1 ~ 4; measure in the order of 2% HNO3, std1, std2, std3, std4, 2% HNO3, process blank, sample 1, sample 2, sample 3, and calculate the impurity element content of the sample using the working curve obtained by std1 ~ 4 and the signal measurement value of the sample.

[0105] Table 4 Results of spike recovery experiments of 68 impurity elements in 500 μg / g ytterbium oxide solution

[0106]

[0107]

[0108] As shown in Table 4, it is difficult to obtain satisfactory accuracy when using the external standard method to measure the impurity elements in the enriched isotope due to the influence of the sample matrix (the recovery rate of the external standard method is about 50% under 500 mg / kg matrix); however, through the matrix matching correction of the present method, satisfactory recovery rate data were obtained, indicating that the present method can better overcome the matrix effect, accurately measure the content of impurity elements in the enriched isotope, and improve the accuracy of the measurement results.

[0109] In summary, the method provided by the present invention is used to obtain the contents of 68 impurity elements using a very small amount of sample, and through the new matrix effect correction method provided by the present invention, the process blank and the sample are measured using different measurement modes, thereby improving the accuracy of the measurement.

[0110] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for determining the content of impurity elements in enriched isotopes based on HR-ICP-MS, characterized in that: The following steps are involved: (1) dissolving the concentrated isotope to be tested in a solvent to obtain a sample to be tested, and dividing the sample into sample 1, sample 2, and sample 3 of equal volumes; The matrix in the sample to be tested is 2% HNO3; Prepare a blank process according to the above preparation process of the sample to be tested, except that no concentrated isotope to be tested is added; (2) Using the element mixed solution series standard substances, prepare standard solutions with concentrations of 1 μg / kg, 2 μg / kg, 5 μg / kg and 10 μg / kg, respectively, and record them as std1 to 4; Prepare 1 mg / kg element mixed solution standard material as the spiked mother solution, and prepare solutions with spiked concentrations of 20 μg / kg and 50 μg / kg by weighing, which are recorded as std5 and std6 respectively; There is no order of precedence between step (1) and step (2); (3) using a high-resolution inductively coupled plasma mass spectrometer to measure and analyze sample 1, sample 2, and sample 3 obtained in step (1) and the process blank, as well as std1 to 6 obtained in step (2), to obtain a corresponding working curve; The order of measurement is: 2% HNO3, std1, std2, std3, std4, 2% HNO3, process blank, sample 1, sample 2, sample 3, std5, std6; (4) calculating the impurity element content in the process blank according to the working curve of std1-4 measured in step (3); According to the working curves of samples 1 to 3 and std5 and 6 measured in step (3), the impurity element content in the sample to be measured is calculated using the signal values ​​actually measured for samples 1 to 3 and the sensitivity measured for std5 and 6; The difference between the impurity element content in the process blank and the impurity element content in the sample to be tested is divided by the concentration of the concentrated isotope to be tested in the sample to be tested to obtain the impurity element content in the concentrated isotope to be tested.

2. The method according to claim 1, characterized in that In the step (1), at least one of ultrapure water, nitric acid, ammonia water and hydrochloric acid is selected as the solvent according to the different concentrated isotopes to be detected.

3. The method according to claim 1, characterized in that The mass of the concentrated isotope to be detected in the step (1) is 10 mg, and the concentration of the concentrated isotope to be detected in the sample to be detected is 1000 mg / kg.

4. The method according to claim 1, characterized in that: The element mixed solution series standard substances in step (2) comply with GBW(E)082428-082431.

5. The method according to claim 1, characterized in that: In the step (3), the nuclide with the highest abundance is selected as the impurity element / ion to be detected.

6. The method according to claim 5, characterized in that In the step (3), the resolution mode of the measurement and analysis is set according to the resolution required to distinguish the interfering ions of the impurity elements / ions to be measured.

7. The method according to claim 6, characterized in that When the required resolution is less than 400, the low-resolution mode is set; when the required resolution is between 400 and 4000, the medium-resolution mode is set; when the required resolution is greater than 4000, the high-resolution mode is set.

8. The method according to claim 1, characterized in that: The detection parameters of the high-resolution inductively coupled plasma mass spectrometer in the step (3) are: RF generator power 1250 kW; cooling gas flow rate 16 L / min, auxiliary gas flow rate 0.8-1.0 L / min, nebulizing gas flow rate 0.9-1.2 L / n in; injection rate 0.1-0.2 mL / n in, sampling time 20-100 ms / element; acceleration voltage -2 kV.

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