Method for testing trace metal impurities in organic lanthanide precursors

Abstract

The present application belongs to the technical field of trace impurity analysis, and relates to a testing method for trace metal impurities in organic lanthanum precursors, which comprises the following steps: first, mixing the organic lanthanum precursor and a digestion solution to obtain a sample digestion solution through digestion; then, obtaining a sample loading solution through pretreatment of the sample digestion solution; next, loading the sample loading solution into a TODGA resin column for elution treatment to obtain a to-be-tested solution; and finally, testing the content of metal impurities in the to-be-tested solution through inductively coupled plasma mass spectrometry; before trace analysis through the inductively coupled plasma mass spectrometry, efficient separation of La and to-be-tested elements in the to-be-tested solution is realized, the removal rate of La is preferably as high as 99% or more, the testing accuracy of the to-be-tested elements is improved, the relative error between the testing value and the actual value is as low as 10% or less, and high-precision analysis of trace metal impurities in the organic lanthanum precursor is realized.

Description

Technical Field

[0001] This invention relates to the field of trace impurity analysis technology, and in particular to a method for testing trace metal impurities in organolanthanum precursors. Background Technology

[0002] With the rapid development of industries such as new energy vehicles, wind power generation, consumer electronics, and high-end displays, the market demand for high-purity lanthanide materials is increasing, placing increasingly stringent requirements on the content of trace metal impurities. For example, in semiconductor manufacturing, organolanthanum compounds used as precursors for chemical vapor deposition or atomic layer deposition need to have their internal metal and other impurity content controlled at one part per billion (ppb) or even lower to prevent these impurities from introducing defects into the chip and affecting device performance and reliability. Therefore, establishing a method to accurately determine the ppb level or even lower content of metal impurities in high-purity organolanthanum precursors is crucial for materials research and development, quality control, and semiconductor process safety.

[0003] Inductively coupled plasma mass spectrometry (ICP-MS) is currently the most sensitive and widely used technique for trace and ultra-trace element analysis. However, when using ICP-MS to directly determine trace impurities in high-concentration organolanthanum precursor solutions (typically with La concentrations ranging from a few percent to tens of percent), significant challenges arise, primarily stemming from the major element La itself. These challenges are detailed below: (1) Mass Spectrometry Interference: High concentrations of La in plasma will produce severe mass spectral interference. Essentially, this is because interfering ions and target impurity ions generate signals at the same mass-to-charge ratio (m / z), leading to signal overlap and indistinguishability. This mainly includes: polyatomic ion interference: formed by La combining with other elements in the plasma or sample (such as O, H, C, or Ar, etc.), such as... 139 La 16 O + (Mass number 155) will interfere 155 Gd + superior; 139 LaH + (Mass number 140) will interfere 140 Ce + ; 139 La 12 C + (Mass number 151) will interfere 151 Eu + ; 138 La 36 Ar + (Mass number 174) will interfere 174 Yb+ Isotope interference: 138 Lahe 138 Ba atoms have identical mass numbers, resulting in complete signal overlap; double-charged ion interference: some La atoms lose two electrons in the high-temperature plasma to form La. 2+ Its apparent mass-to-charge ratio (m / z) is half of its mass number, which may interfere with the single-charged ions of other elements.

[0004] (2) Non-mass spectrometry interference (matrix effect): High concentrations of La alter the physicochemical properties of the sample, without affecting mass spectrometry identification (m / z), but significantly reduce and interfere with signal intensity. This is mainly manifested in: signal suppression and drift: High-concentration matrix reduces plasma ionization efficiency and aerosol transport efficiency, leading to widespread and unstable attenuation of impurity signals, rendering the standard curve method ineffective; cone deposition and blockage: La and its oxides deposit on the surface of the interface cone (sampling cone, truncation cone), causing cone narrowing or even blockage, resulting in a sudden drop in signal, increased background, and deteriorated reproducibility, requiring frequent maintenance and making long-term stable analysis difficult; space charge effect: Large amounts of La... + Space charge repulsion occurs in the ion lens region, hindering the transport of other positive ions and resulting in a systematic underestimation of quantitative results.

[0005] To overcome the aforementioned drawbacks, the direct high-dilution method is commonly used in this field. This involves drastically diluting the sample (thousands to tens of thousands of times) with acid or solvent to reduce the La matrix concentration to the mg / L level before direct injection. While this method is simple to operate, it has two major limitations when applied to organolanthanum precursors: insufficient detection limits—after diluting trace impurities proportionally with La, their concentration often drops to near or even below the instrument's detection limit, making accurate quantification impossible; and interference residues—even when the La concentration is reduced, its polyatomic ions (such as LaO₂) remain. + Interference with adjacent mass numbers (such as Ce and Gd) still exists at unit mass resolution and is difficult to eliminate; the risk of contamination increases, as the high-dilution process introduces a large amount of solvent and contact glassware, which significantly increases the risk of contamination from the environment and reagents, which can easily affect ultra-trace analysis.

[0006] Therefore, how to provide a method for testing the content of trace metal impurities in organolanthanum precursors, and fundamentally solve the mass spectrometry and non-mass spectrometry interference caused by La, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a method for testing trace metal impurities in organolanthanum precursors. This method solves the problem in existing technologies where Ce, Gd, or Pr, which are affected by the major element La, cannot be accurately measured in organolanthanum precursors. It effectively avoids the loss of analyte recovery rate. Furthermore, the method has a simple procedure, consumes less reagent, and reduces testing costs.

[0008] To achieve this objective, the present invention adopts the following technical solution: This invention provides a method for testing trace metal impurities in organolanthanum precursors, the method comprising the following steps: (1) Mix the organic lanthanum precursor and digestion solution, and digest to obtain a sample digestion solution; the sample digestion solution is pretreated to obtain a loading solution; (2) Load the sample solution described in step (1) onto a TODGA resin column for elution to obtain the test solution; (3) The solution to be tested in step (2) is subjected to inductively coupled plasma mass spectrometry to test the content of metal impurities.

[0009] The testing method of this invention adds an elution step in a TODGA resin column before introducing the test solution into the inductively coupled plasma mass spectrometer (ICP-MS) to separate the major element La and the analyte. This significantly reduces the La content in the test solution while avoiding the loss of analyte recovery rate, thus fundamentally solving the mass spectrometry and non-mass spectrometry interference caused by La and improving the testing accuracy of trace metal impurities in the organolanthanum precursor.

[0010] It is worth noting that the testing method described in this invention is for organolanthanum precursor samples, which are more difficult to separate rare earth elements from geological samples (such as soil and minerals). The specific reasons are as follows: ① The concentration difference between La and other trace metal impurities in the organolanthanum precursor is as high as 9 orders of magnitude, while the concentration difference between La and other trace metal impurities in the geoscience sample is only within 2 to 3 orders of magnitude. ② The content of the organolanthanum precursor La (10~80wt%) is higher than that of the geoscientific sample (ppm level), which poses a risk of exceeding the column capacity. After experimental verification, the amount of La passed through the column should be less than 500μg. The organolanthanum precursor needs to be digested and diluted before loading. If the dilution factor is reduced or the La content is controlled to be lower, multiple column passes are required. ③ In geoscience samples, the concentration of the target element is significantly higher than that of high-purity organic lanthanum precursors, making them suitable for isotope analysis. This method requires obtaining a pure solution of each element, followed by separation using acids of varying concentrations, resulting in extremely high acid consumption and long experimental times. However, in the field of electronic chemicals, the content of the target trace element in high-purity organic lanthanum precursors is even lower, and the high acid consumption and long experimental times pose a risk of introducing reagent blanks. Furthermore, the testing method described in this invention aims for high-precision concentration testing, and to shorten testing time and reduce costs, it is more suitable for sample solutions containing multiple trace elements.

[0011] Preferably, the lanthanum content in the organic lanthanum precursor in step (1) is 10~80 wt%, for example, it can be 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt% or 80 wt%, etc.

[0012] Preferably, the elements in the organic lanthanum precursor in step (1) include La, Y, Nd, Sm, Eu, Tb, Dy, Er, Tm, Lu, Gd, Ce, Pr, Yb and Ba.

[0013] Preferably, the solid-liquid ratio of the organic lanthanum precursor to the digestion solution in step (1) is 1:(2~50) g / mL, for example, it can be 1:2 g / mL, 1:5 g / mL, 1:10 g / mL, 1:20 g / mL, 1:30 g / mL, 1:40 g / mL or 1:50 g / mL, etc.

[0014] In a further preferred embodiment of the present invention, the solid-liquid ratio of the organolanthanum precursor to the digestion solution in step (1) is within the above-mentioned range. This facilitates the complete digestion of the organolanthanum precursor, converting the compound into free ions, while avoiding blanks introduced due to excessive digestion solution. If the solid-liquid ratio of the organolanthanum precursor to the digestion solution is too large, i.e., the amount of digestion solution added is too small, the organolanthanum precursor will not be fully digested, resulting in a decrease in the accuracy of the test of the content of the analyte element. If the solid-liquid ratio of the organolanthanum precursor to the digestion solution is too small, i.e., the amount of digestion solution added is too large, a blank will be introduced, which will also interfere with the test, resulting in a higher test recovery rate, while wasting reagents and increasing costs.

[0015] Preferably, the digestion solution in step (1) includes a mixture of nitric acid, nitric acid and hydrofluoric acid, or a mixture of nitric acid and hydrochloric acid.

[0016] Preferably, the concentration of the nitric acid is 50-69 wt%, for example, it can be 50 wt%, 52 wt%, 55 wt%, 58 wt%, 60 wt%, 62 wt%, 65 wt%, or 69 wt%.

[0017] Preferably, the concentration of the hydrofluoric acid is 39-49 wt%, for example, it can be 39 wt%, 42 wt%, 44 wt%, 46 wt%, or 49 wt%.

[0018] Preferably, the concentration of the hydrochloric acid is 30-37 wt%, for example, it can be 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, or 37 wt%.

[0019] Preferably, when the digestion solution in step (1) is a mixed solution, the volume ratio of the two acids in the mixed solution is 1:(0.2~3), for example, it can be 1:0.2, 1:0.5, 1:1, 1:2 or 1:3, etc.

[0020] Preferably, the digestion solution in step (1) further includes hydrogen peroxide.

[0021] Preferably, based on the digestion solution being 100 vol%, the amount of hydrogen peroxide added is 33~50 vol%, for example, it can be 33 vol%, 35 vol%, 38 vol%, 40 vol%, 42 vol%, 45 vol%, 48 vol%, or 50 vol%.

[0022] Preferably, the digestion temperature in step (1) is 140~180℃, for example, it can be 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, 175℃ or 180℃, etc.

[0023] Preferably, the digestion time in step (1) is 1 to 2 hours, for example, 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours or 2 hours.

[0024] Preferably, the La content in the sample solution in step (1) is ≤500 μg, for example, it can be 500 μg, 480 μg, 460 μg, 440 μg, 420 μg or 400 μg, etc.

[0025] The test method of the present invention further optimizes the step (1) by ensuring that the La content in the sample solution is ≤500 μg, so as to ensure that the La content in the test solution is less than 10 ppb and the effective removal rate of La reaches more than 99%. If the La content in the sample solution is >500 μg, it will exceed the column capacity, resulting in insufficient La removal rate. The La in the test solution will still have a concentration at the ppm level, and La will cause mass spectrometry interference to the test element, causing the test value to deviate from the true value.

[0026] Preferably, the pretreatment in step (1) includes sequentially adjusting the volume of the sample digestion solution and evaporating it to dryness before dissolving it in hydrochloric acid solution.

[0027] Preferably, the concentration of the hydrochloric acid solution used in the pretreatment process in step (1) is 3~3.5 mol / L, for example, it can be 3 mol / L, 3.1 mol / L, 3.2 mol / L, 3.3 mol / L, 3.4 mol / L or 3.5 mol / L, etc.

[0028] Preferably, the elution process in step (2) includes eluting the loaded TODGA resin column sequentially through elution solution A, elution solution B and elution solution C.

[0029] Preferably, the rinsing solution A comprises a hydrochloric acid solution with a concentration of 3~3.5 mol / L, such as 3 mol / L, 3.1 mol / L, 3.2 mol / L, 3.3 mol / L, 3.4 mol / L, or 3.5 mol / L.

[0030] Preferably, the rinsing solution B comprises a hydrochloric acid solution with a concentration of 3~3.5 mol / L, such as 3 mol / L, 3.1 mol / L, 3.2 mol / L, 3.3 mol / L, 3.4 mol / L, or 3.5 mol / L.

[0031] Preferably, the rinsing solution C comprises a hydrochloric acid solution with a concentration ≤0.1 mol / L, such as 0.1 mol / L, 0.08 mol / L, 0.07 mol / L, 0.06 mol / L, or 0.05 mol / L.

[0032] Preferably, by volume, the rinsing solution A is 5-6 parts, the rinsing solution B is 16-20 parts, and the rinsing solution C is 15-17 parts.

[0033] The rinsing solution A is 5-6 parts, for example, 5 parts, 5.2 parts, 5.4 parts, 5.6 parts, 5.8 parts, or 6 parts; the rinsing solution B is 16-20 parts, for example, 16 parts, 17 parts, 18 parts, 19 parts, or 20 parts; and the rinsing solution C is 15-17 parts, for example, 15 parts, 15.5 parts, 16 parts, 16.5 parts, or 17 parts.

[0034] In the test method described in this invention, when the TODGA resin column after sample loading is sequentially eluted through eluent A, eluent B, and eluent C, specifically, 5-6 parts of eluent A (a hydrochloric acid solution with a concentration of 3-3.5 mol / L) are first used to elute and collect Ba, then 16-20 parts of eluent B (a hydrochloric acid solution with a concentration of 3-3.5 mol / L) are used to fully remove La, and then 15-17 parts of eluent C (a hydrochloric acid solution with a concentration of ≤0.1 mol / L) are used to collect other analytes that are affected by La (such as Ce, Gd, Pr, etc.). The resulting La-free analyte solution is then tested.

[0035] Compared to the traditional method of testing after direct dilution, this invention first fully removes the interfering element La to effectively avoid La interference; compared to the elution process in the geoscience field, it effectively reduces the amount of eluent used and shortens the test time.

[0036] Preferably, the TODGA resin column in step (2) is obtained by filling an ion exchange column with TODGA resin.

[0037] Preferably, the particle size of the TODGA resin is 50~100 μm, for example, it can be 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm.

[0038] Preferably, the testing method further includes a first cleaning of the TODGA resin before filling.

[0039] Preferably, the first cleaning includes soaking the TODGA resin in hydrochloric acid solution and water in sequence.

[0040] Preferably, the concentration of the hydrochloric acid solution used for the first cleaning is 6-7 mol / L, for example, it can be 6 mol / L, 6.2 mol / L, 6.5 mol / L, 6.8 mol / L or 7 mol / L, etc.

[0041] Preferably, the testing method further includes a second cleaning of the TODGA resin column after filling.

[0042] Preferably, the concentration of the hydrochloric acid solution used for the second cleaning is 6-7 mol / L, for example, it can be 6 mol / L, 6.2 mol / L, 6.5 mol / L, 6.8 mol / L or 7 mol / L, etc.

[0043] Preferably, the test method further includes activating the TODGA resin column before the elution process in step (2).

[0044] Preferably, the activation treatment is carried out using a 3-3.5 mol / L hydrochloric acid solution, such as 3 mol / L, 3.1 mol / L, 3.2 mol / L, 3.3 mol / L, 3.4 mol / L, or 3.5 mol / L.

[0045] Compared with the prior art, the present invention has at least the following beneficial effects: The method for testing trace metal impurities in organolanthanum precursors provided by this invention involves eluting the test solution with a TODGA resin column before it enters the inductively coupled plasma mass spectrometer (ICP-MS). Further optimization of the digestion solid-liquid ratio, the acid used for elution, and its concentration and volume distribution, combined with other factors, results in a La removal rate of over 99% in the test solution. This achieves highly efficient separation of La from other analyte metals in the sample digestion solution, fundamentally resolving the mass spectrometry and non-mass spectrometry interference caused by La. This improves the accuracy of subsequent ICP-MS analysis, with the relative error between the measured and actual values ​​as low as 10%. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the elution process in the method for testing trace metal impurities in the organolanthanum precursor provided in Example 1 of the present invention.

[0047] Figure 2 This is a rinsing curve of each element in the test method for trace metal impurities in the organolanthanum precursor provided in Example 1 of the present invention.

[0048] Figure 3 This is a comparison chart of the La concentration in the Gd eluent in Examples 5 and 9, and Examples 6 and 10 of the present invention. Detailed Implementation

[0049] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0050] Before digestion of the organic precursor described in step (1) in the following examples or comparative examples, it is first subjected to active quenching, that is, it is first placed in an anhydrous and oxygen-free operating chamber at normal temperature and pressure (25℃, 101kPa) for 8 hours.

[0051] The ultrapure water used in the following examples or comparative examples has a resistivity of ≥18.2 MΩ·cm.

[0052] The TODGA resin used in the following examples was purchased from Beijing Wodelu Technology Co., Ltd., with product number DN-B25-S and resin size of 50~100μm.

[0053] The standard solutions described in the following examples contain the analyte elements La, Y, Nd, Sm, Eu, Tb, Dy, Er, Tm, Lu, Gd, Ce, Pr, Yb, and Ba, with each analyte having a concentration of 100 μg / L. This facilitates subsequent accuracy evaluation of the test method using the spiked recovery test method.

[0054] I. Implementation Examples Example 1 This embodiment provides a method for testing trace metal impurities in organolanthanum precursors, the method comprising the following steps: (1) Mix 0.1 g of organic lanthanum precursor (lanthanum content 44 wt%), 3 mL of digestion solution and 1 mL of hydrogen peroxide (30 wt%), and digest at 160 °C for 1.5 h to obtain sample digestion solution; add ultrapure water to the sample digestion solution to make up to 100 mL, then take 1 mL of the sample digestion solution, add 0.1 mL of standard solution, evaporate to dryness and then dissolve in 0.1 mL of 3.3 mol / L hydrochloric acid solution to obtain sample loading solution (La content 440 μg). The digestion solution comprises a mixed solution of 2 mL nitric acid (55 wt%) and 1 mL hydrofluoric acid (49 wt%). (2) First, soak 20 mL of TODGA resin in 60 mL of hydrochloric acid solution (6 mol / L) for 24 hours, then remove the supernatant. Next, soak the TODGA resin in 60 mL of ultrapure water for 24 hours, then remove the supernatant. Repeat this process twice. Then, pack the cleaned TODGA resin into an ion exchange column with an inner diameter of 7 mm, an outer diameter of 10 mm, and a length of 10 cm. The packing height is 5 cm, resulting in a TODGA resin column. According to... Figure 1 The procedure shown involves first cleaning the TODGA resin column by adding 10 mL of hydrochloric acid solution (6.5 mol / L) dropwise, followed by adding 10 mL of ultrapure water dropwise, repeating this cleaning process twice. Then, the cleaned TODGA resin column is activated with 5 mL of hydrochloric acid solution (3.3 mol / L). Finally, the sample loading solution described in step (1) is loaded onto the activated TODGA resin column for elution. The elution process includes sequentially passing the column through eluent A, ... Eluent B and eluent C were used for elution, specifically as follows: Ba was first eluted with 6 mL of 3.3 mol / L hydrochloric acid solution (eluent A) and collected; then La was eluted with 20 mL of 3.3 mol / L hydrochloric acid solution (eluent B); followed by elution with 17 mL of 0.1 mol / L hydrochloric acid solution (eluent C) to obtain Gd eluent (containing all trace elements to be measured except Ba). The eluent was collected and evaporated to obtain the test solution (La removal rate was as high as 99.5%). like Figure 2As shown in the figure, the elution curves of each element in the above elution process can be seen that: Ba is eluted first in the first 5-6 mL of elution buffer, La is eluted in the next 16-20 mL of elution buffer, and Ce, Pr, Nd, Eu, Gd, Yb and Lu are completely eluted in the last 15-17 mL of elution buffer. La is effectively separated from each element to be measured.

[0055] (3) The solution to be tested in step (2) is subjected to inductively coupled plasma mass spectrometry to test the content of metal impurities.

[0056] Example 2 This embodiment provides a method for testing trace metal impurities in organolanthanum precursors, the method comprising the following steps: (1) Mix 0.1 g of organic lanthanum precursor (lanthanum content 44 wt%), 2 mL of digestion solution (55 wt% nitric acid) and 1 mL of hydrogen peroxide (35 wt%), and digest at 140 °C for 2 h to obtain sample digestion solution; add ultrapure water to the sample digestion solution to make up to 100 mL, then take 1 mL of the sample digestion solution, evaporate to dryness and then dissolve in 3 mol / L hydrochloric acid solution to obtain sample loading solution (La content 440 μg). (2) First, soak 20 mL of TODGA resin in 60 mL of hydrochloric acid solution (6 mol / L) for 24 h and then remove the supernatant. Then soak the TODGA resin in 60 mL of ultrapure water for 24 h and then remove the supernatant. Repeat the above steps twice. Then pack the cleaned TODGA resin into an ion exchange column (same as in Example 1). The TODGA resin column was then cleaned by first adding 10 mL of hydrochloric acid solution (6 mol / L) dropwise, followed by adding 10 mL of ultrapure water dropwise, repeating the cleaning process twice. Then, the cleaned TODGA resin column was activated with 5 mL of hydrochloric acid solution (3 mol / L). The sample solution from step (1) was then loaded onto the activated TODGA resin column for elution. The elution process involved sequential elution with eluent A, eluent B, and eluent C. Specifically, Ba was eluted with 5 mL of 3 mol / L hydrochloric acid solution (eluent A) and collected. La was then eluted with 16 mL of 3 mol / L hydrochloric acid solution (eluent B), followed by elution with 16 mL of 0.05 mol / L hydrochloric acid solution (eluent C) to obtain a Gd eluent (containing all trace elements except Ba). This eluent was collected and evaporated to obtain the test solution. (3) The solution to be tested in step (2) is subjected to inductively coupled plasma mass spectrometry to test the content of metal impurities.

[0057] Example 3 This embodiment provides a method for testing trace metal impurities in organolanthanum precursors, the method comprising the following steps: (1) Mix 0.1 g of organic lanthanum precursor (lanthanum content is 50 wt%), 4 mL of digestion solution and 1 mL of hydrogen peroxide (30 wt%), and digest at 180 °C for 1 h to obtain sample digestion solution; add ultrapure water to the sample digestion solution to make up to 100 mL, then take 1 mL of the sample digestion solution, evaporate to dryness and then dissolve in 3.5 mol / L hydrochloric acid solution to obtain sample loading solution (La content is 500 μg). The digestion solution comprises a mixed solution of 1 mL nitric acid (55 wt%) and 3 mL hydrochloric acid (30 wt%). (2) First, soak 20 mL of TODGA resin in 60 mL of hydrochloric acid solution (7 mol / L) for 24 h and then remove the supernatant. Then soak the TODGA resin in 60 mL of ultrapure water for 24 h and then remove the supernatant. Repeat the above steps twice. Then pack the cleaned TODGA resin into an ion exchange column (same as in Example 1). The TODGA resin column was then cleaned by first adding 10 mL of 7 mol / L hydrochloric acid solution dropwise, followed by adding 10 mL of ultrapure water dropwise, repeating the cleaning process twice. Then, 5 mL of 3.4 mol / L hydrochloric acid solution was used to activate the cleaned TODGA resin column. The sample solution from step (1) was then loaded onto the activated TODGA resin column for elution. The elution process involved sequential elution with eluent A, eluent B, and eluent C. Specifically, Ba was eluted with 6 mL of 3.4 mol / L hydrochloric acid solution (eluent A) and collected. La was then eluted with 20 mL of 3.4 mol / L hydrochloric acid solution (eluent B). Finally, 17 mL of ultrapure water solution (eluent C) was used for elution to obtain a Gd eluent (containing all trace elements except Ba). This eluent was collected and evaporated to obtain the test solution. (3) The solution to be tested in step (2) is subjected to inductively coupled plasma mass spectrometry to test the content of metal impurities.

[0058] Examples 4 to 8 Keeping other conditions unchanged in Example 1, only the La content of the sample solution obtained in step (1) is changed to explore the effect of the La content in the sample solution on the La removal rate. Specifically, in Example 4 to Example 8, the La content in the sample solution obtained in step (1) is controlled to be 10 μg, 100 μg, 500 μg, 1000 μg or 5000 μg respectively.

[0059] Example 9 This embodiment provides a method for testing trace metal impurities in organolanthanum precursors. Except for the two column passes, the testing method is the same as in Example 5.

[0060] Example 10 This embodiment provides a method for testing trace metal impurities in organolanthanum precursors. Except for the two column passes, the testing method is the same as in Example 6.

[0061] II. Comparative Example Comparative Example 1 This comparative example provides a method for testing trace metal impurities in an organolanthanum precursor. The method is the same as in Example 1 except that step (2) is omitted, and instead, a 2wt% dilute nitric acid solution is used to dilute the digestion solution in step (1) by 1000 times until the La content is less than 0.1%, and then a standard solution is added until the concentration of the element to be tested is the same as in Example 1.

[0062] In this comparative example, the traditional dilution method was used, which resulted in the simultaneous dilution of the analyte and La, leading to a loss of sensitivity in subsequent tests. Furthermore, even though the La concentration decreased after dilution, the polyatomic ions it produced (such as LaO₂) remained unchanged. + Interference with adjacent mass numbers (such as with Gd) still exists at unit mass resolution, especially for elements with mass numbers not much different from La; moreover, the high-dilution process introduces a large amount of solvent (such as dilute nitric acid) and contact vessels, which significantly increases the risk of contamination from the environment and reagents, which is not conducive to ultra-trace analysis.

[0063] III. Tests and Results ① The concentrations of the target elements (Y, Nd, Sm, Eu, Tb, Dy, Er, Tm, Lu, Gd, Ce, Pr, Yb and Ba) in the organolanthanum precursor were tested according to the test methods provided in Examples 1 to 3 and Comparative Example 1, respectively. The actual concentration values ​​of the corresponding elements were obtained, and the recovery rates of the corresponding elements were calculated in combination with the theoretical concentration values ​​to evaluate the accuracy of the test methods. The results are shown in Table 1. Table 1 ② The concentration of La in the Gd eluent (including all trace elements except Ba) obtained by the test methods described in Examples 4 to 10 above was tested, and the La removal rate was calculated according to the following formula. The results are shown in Table 2 and Figure 3 As shown; La removal rate ; Table 2 The test results show that: (1) As can be seen from Examples 1 to 3 and Comparative Example 1, the method for testing trace impurities in organolanthanum precursors provided by the present invention removes interfering element La by fully separating La from the analyte before testing, with a removal rate of over 99%, thereby improving the accuracy of subsequent testing of the analyte and reducing the relative error to below 10%. In contrast, Comparative Example 1 uses the traditional method of direct testing after dilution, which results in a large error between the test value and the actual value and low test accuracy. In particular, the relative error for testing the concentrations of Eu, Gd, Ce, Pr and Ba is too high and deviates far from the theoretical concentration value.

[0064] (2) As can be seen from Examples 4 to 8, when the La content in the loading solution is less than 500 μg, the La concentration in the Gd eluent can be controlled below 10 ppb; as can be seen from Examples 5 and 9, and Examples 6 and 10, multiple column passes can effectively reduce the La concentration in the Gd eluent, i.e., the La residue (e.g., ...). Figure 3 As shown in the figure, the La removal rate is improved, thereby improving the accuracy of the test of trace metal element content in the organolanthanum precursor.

[0065] In summary, the testing method of this invention achieves efficient separation of La and other analyte metal elements in the sample digestion solution by using a TODGA resin column for elution treatment before the test solution enters the inductively coupled plasma mass spectrometer. Furthermore, by further optimizing the La content in the sample loading solution in step (2) to ≤500 μg, the La removal rate is further improved, fundamentally solving the mass spectrometry and non-mass spectrometry interference caused by La when testing the trace metal impurities in organolanthanum precursors, and improving the analytical accuracy.

[0066] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for testing trace metal impurities in organolanthanum precursors, characterized in that, The testing method includes the following steps: (1) Mix the organic lanthanum precursor and digestion solution, and digest to obtain a sample digestion solution; the sample digestion solution is pretreated to obtain a loading solution; the La content in the loading solution is ≤500μg; (2) Load the sample solution described in step (1) onto a TODGA resin column for elution to obtain the test solution; (3) The solution to be tested in step (2) is subjected to inductively coupled plasma mass spectrometry to test the content of metal impurities.

2. The test method according to claim 1, characterized in that, The lanthanum content in the organolanthanum precursor in step (1) is 10~80 wt%; The elements in the organic lanthanum precursor in step (1) include La, Y, Nd, Sm, Eu, Tb, Dy, Er, Tm, Lu, Gd, Ce, Pr, Yb and Ba.

3. The test method according to claim 1, characterized in that, In step (1), the solid-liquid ratio of the organic lanthanum precursor to the digestion solution is 1:(2~50)g / mL; The digestion solution in step (1) includes nitric acid, a mixed solution of nitric acid and hydrofluoric acid, or a mixed solution of nitric acid and hydrochloric acid; When the digestion solution in step (1) is a mixed solution, the volume ratio of the two acids in the mixed solution is 1:(0.2~3).

4. The test method according to claim 3, characterized in that, The digestion solution in step (1) also includes hydrogen peroxide; based on the digestion solution being 100 vol%, the amount of hydrogen peroxide added is 33~50 vol.

5. The test method according to claim 1, characterized in that, The digestion temperature in step (1) is 140~180℃; The digestion time in step (1) is 1 to 2 hours.

6. The test method according to claim 1, characterized in that, The pretreatment in step (1) includes sequentially adjusting the volume of the sample digestion solution and evaporating it to dryness before dissolving it in hydrochloric acid solution; The concentration of the hydrochloric acid solution used in the pretreatment process in step (1) is 3~3.5 mol / L.

7. The test method according to claim 1, characterized in that, The elution process in step (2) includes eluting the loaded TODGA resin column sequentially through eluent A, eluent B and eluent C; The rinsing solution A comprises a hydrochloric acid solution with a concentration of 3~3.5 mol / L; The rinsing solution B comprises a hydrochloric acid solution with a concentration of 3~3.5 mol / L; The rinsing solution C comprises a hydrochloric acid solution with a concentration ≤0.1 mol / L; By volume, the rinsing solution A is 5-6 parts, the rinsing solution B is 16-20 parts, and the rinsing solution C is 15-17 parts.

8. The test method according to claim 1, characterized in that, The TODGA resin column in step (2) is obtained by filling an ion exchange column with TODGA resin. The particle size of the TODGA resin is 50~100 μm.

9. The test method according to claim 8, characterized in that, The test method also includes a first cleaning of the TODGA resin before filling; The first cleaning process involves sequentially soaking the TODGA resin in hydrochloric acid solution and water. The concentration of the hydrochloric acid solution used for the first cleaning is 6-7 mol / L; The test method further includes a second cleaning of the TODGA resin column after filling. The concentration of the hydrochloric acid solution used for the second cleaning is 6-7 mol / L.

10. The test method according to claim 1, characterized in that, The test method further includes activating the TODGA resin column before the elution process in step (2); The activation treatment is carried out using a 3-3.5 mol / L hydrochloric acid solution.

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