Method for detecting content of trace elements in titanium dioxide through ICP-OES

Abstract

The invention belongs to the technical field of titanium dioxide production, and particularly relates to a method for detecting the content of trace elements in titanium dioxide through ICP-OES. Comprising the following steps: S1, weighing a titanium dioxide sample, digesting the titanium dioxide sample by adopting a hydrochloric acid-nitric acid-hydrofluoric acid system to obtain a first sample, and dividing the first sample into a plurality of parts; s2, taking one first sample as a substrate sample, respectively adding mixed standard solutions with different concentrations into other first samples, and respectively fixing the volumes of the mixed standard solutions and the substrate sample to obtain a second sample and the substrate sample after the volume fixing; s3, preparing ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer) with a hydrofluoric acid-resistant sampling system, detecting the substrate sample and the second sample after volume metering, and generating a standard curve based on a detection result; and S4, based on the standard curve, calculating the content result of the trace elements in the substrate sample. The method provided by the invention overcomes the problems of difficult dissolution of titanium dioxide, more interference of trace element measurement and the like, is simple, convenient and rapid to operate, and effectively ensures the accuracy of a detection result.

Description

Technical Field

[0001] This invention belongs to the field of titanium dioxide production technology, specifically relating to a method for detecting trace element content in titanium dioxide using ICP-OES. Background Technology

[0002] Titanium dioxide, as an excellent white pigment, exhibits a significant impact on its color and application performance due to the presence of trace elements. Accurate determination and effective control of trace element content are crucial for managing the color and performance of titanium dioxide. Currently, trace element analysis in titanium dioxide is primarily performed using the XRF dry method. However, accurate XRF determination requires the establishment of a standard curve using standard samples with the same or similar matrix. Since suitable standard samples are often unavailable, the ICP-OES wet method is employed to establish the XRF standard curve. Establishing the standard curve using standard solutions on ICP-OES allows for the selection and correction of spectral lines to avoid interference.

[0003] As the application fields of titanium dioxide continue to expand, the requirements for its purity and performance are becoming increasingly stringent. Impurities such as Fe, Cr, V, and Cu can cause a decrease in product whiteness and a shift in hue. Fluctuations in the content of elements such as K, Mg, and P can affect its dispersibility and processing suitability. Therefore, accurate trace element detection has become a core aspect of quality control.

[0004] Existing detection methods have significant limitations. For example, patent document CN202510626334.8 discloses a method for rapidly measuring solid-solid metal impurities and surface free metal impurities in raw titanium dioxide. This method uses ICP-OES or ICP-MS for detection, achieving separation of solid-solid and free states by selectively dissolving surface free impurities with dilute acid. However, it can only detect six elements: Fe, Cu, Ni, Al, Cr, and V. It does not cover key elements such as K, Co, Zn, Mg, and P, which have a significant impact on the application performance of titanium dioxide. Furthermore, it does not design solutions to address the synergistic interference between the titanium matrix and coexisting elements such as Zr, Al, and Si on the detection of specific elements. The detection range and accuracy cannot meet the comprehensive quality control requirements.

[0005] Another existing technology (Yan Pengfei et al., Determination of 16 Elements in Ti65 High-Temperature Titanium Alloy by Inductively Coupled Plasma Atomic Emission Spectrometry, Journal of Analytical Testing, 2024) discloses the use of a hydrochloric acid-hydrofluoric acid-nitric acid mixed acid system to dissolve the sample, and the elimination of interference through matrix matching and alloy element matching methods to achieve the detection of 16 elements in titanium alloy. However, this technology is applied to Ti65 high-temperature titanium alloy, whose matrix composition is fundamentally different from that of titanium dioxide. Moreover, it lacks key control elements for titanium dioxide such as P and Zn. In addition, the matrix matching method it relies on requires simulating a complex alloy matrix composition, which is cumbersome and unsuitable for the detection scenario of titanium dioxide, where the matrix is ​​relatively simple but needs to cover multiple trace elements. Therefore, it cannot be directly transferred to the accurate determination of titanium dioxide.

[0006] Furthermore, traditional detection methods generally suffer from incomplete sample digestion, insufficient targeted interference elimination, and incomplete coverage of detectable elements, resulting in poor reliability of detection results. These methods fail to meet the accuracy and comprehensiveness requirements of ICP-OES wet determination, thus affecting the precision of establishing standard curves for XRF. Therefore, developing an ICP-OES method for the detection of trace elements in titanium dioxide that provides comprehensive element coverage, significant interference elimination, simple operation, and accurate results has become a pressing technical challenge in this field. Summary of the Invention

[0007] In view of this, in order to solve the problems mentioned in the background art, the purpose of this invention is to provide a method for detecting trace element content in titanium dioxide by ICP-OES, which overcomes the problems of titanium dioxide being difficult to dissolve and numerous interferences in trace element measurement. The method completes sample dissolution and analysis through instrument parameter settings and analytical wavelength selection, and is simple, fast, and effectively ensures the accuracy of the detection results.

[0008] The technical solution of the present invention includes the following: This invention provides a method for detecting the trace element content in titanium dioxide, comprising the following steps: S1. Weigh the titanium dioxide sample, digest the titanium dioxide sample using a hydrochloric acid-nitric acid-hydrofluoric acid system to obtain the first sample, and divide the first sample into multiple portions; S2. Take one first sample as the base sample, add mixed standard solutions of different concentrations to the other first samples respectively, and make up the volume with the base sample to form the second sample and the base sample after volume adjustment; S3. Prepare an ICP-OES system with a hydrofluoric acid resistant injection system, detect the substrate sample and the second sample after volume adjustment, and generate a standard curve based on the detection results; S4. Based on the standard curve, calculate the content of trace elements in the substrate sample; The mixed standard solution contains the elements Fe, Si, Ni, K, Zr, Cr, V, Al, Cu, Co, Mg, P and Zn; The concentration gradient of each element in the mixed standard solution corresponds to the content of each element in the titanium dioxide sample.

[0009] In some embodiments, in step S1, hydrochloric acid-nitric acid-hydrofluoric acid are used sequentially, with the volume ratio of hydrofluoric acid to nitric acid being 1:1. The digestion temperature is maintained at a slight boil on an electric furnace, and the digestion time is 25-30 minutes.

[0010] In some embodiments, in step S1, the amount of the titanium dioxide sample is selected from 0.2 to 0.3 g.

[0011] In some embodiments, in step S2, the volume adjustment is performed using 3-6% hydrochloric acid to bring the volume to 100 ml. In some embodiments, during the detection in S3, the preset parameters of the ICP-OES instrument are: RF power 1100~1200w; carrier gas flow rate 0.3~0.6L / min; carrier gas pressure 1.5~1.7bar; auxiliary gas flow rate 0.3~0.8L / min; cooler flow rate 12.0~15.0L / min; pump speed 40~55rpm. In some embodiments, in S3, the elemental reference analysis lines in the ICP-OES are: P 177.495nm, Zn 202.54nm, Ni 231.6nm, Fe 238.2nm, Si 251.61nm, Mg 279.55nm, Cr 283.56nm, V 289.332nm, Zr 343.82nm, Al 396.15nm, K 766.49nm, Cu 213.598nm, and Co 238.636nm.

[0012] In some embodiments, the standard addition concentration gradient of Al in S2 is 0 mg / L, 2.5 mg / L, 10.0 mg / L, 20.0 mg / L, and 40.0 mg / L; the standard addition concentration gradient of Si is 0 mg / L, 0.2 mg / L, 0.5 mg / L, 2.5 mg / L, 10.0 mg / L, and 20.0 mg / L; the standard addition concentration gradient of Zn, K, and Zr is 0 mg / L, 0.05 mg / L, 0.2 mg / L, 0.5 mg / L, 2.5 mg / L, and 10.0 mg / L; and the concentration gradient of the remaining elements is 0 mg / L, 0.01 mg / L, 0.05 mg / L, 0.2 mg / L, 0.5 mg / L, and 2.5 mg / L. In some embodiments, in step S1, four 0.2g portions of titanium dioxide sample are weighed and placed in a 100mL polytetrafluoroethylene beaker with a lid. 5mL of high-purity hydrofluoric acid and 5mL of high-purity nitric acid are added. The mixture is heated on an electric furnace until it reaches a gentle boil and is maintained for 25-30 minutes until it is completely dissolved. After cooling, the portions are transferred to 100mL plastic volumetric flasks.

[0013] In some embodiments, in step S2, a first sample is taken as a base sample, and mixed standard solutions of different concentrations are added to the base sample and the remaining first samples respectively. The volume is adjusted to 100 mL with 5% hydrochloric acid, and ultrapure water is used to assist in the adjustment during the adjustment to obtain the base sample and the second sample after the adjustment.

[0014] In some embodiments, S3 includes: based on the detection results of the substrate sample and the second sample, based on the actual weighing value and fixed volume of the sample input on the ICP-OES instrument, plotting a standard curve, and after the correlation coefficient of the curve reaches 98%, starting the detection and outputting the mass percentage results of each trace element. The beneficial effects of this invention include: By employing a mixed acid system of hydrochloric acid, nitric acid, and hydrofluoric acid, the invention ensures complete digestion of titanium dioxide samples and sufficient dissolution of trace elements. Furthermore, the use of a standard addition method effectively eliminates interference from the complex matrix of titanium dioxide, significantly improving quantitative accuracy. Combined with an ICP-OES system resistant to hydrofluoric acid injection, multi-element simultaneous detection is achieved, enabling one-time, rapid, and accurate analysis of 13 trace elements, including Fe, Si, Ni, K, Zr, Cr, V, Al, Cu, Co, Mg, P, and Zn. This method has a simple procedure, avoids cumbersome acid removal steps, reduces the risk of contamination and element loss, and provides an efficient and reliable detection solution for titanium dioxide product quality control. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0016] Figure 1 A flowchart of a method provided in one embodiment of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0018] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0019] like Figure 1 As shown, the present invention provides a method for detecting the trace element content in titanium dioxide, comprising the following steps: S1. Weigh the titanium dioxide sample, digest the titanium dioxide sample using a hydrochloric acid-nitric acid-hydrofluoric acid system to obtain the first sample, and divide the first sample into multiple portions; S2. Take one first sample as the base sample, add mixed standard solutions of different concentrations to the other first samples respectively, and make up the volume with the base sample to form the second sample and the base sample after volume adjustment; S3. Prepare an ICP-OES system with a hydrofluoric acid resistant injection system, detect the substrate sample and the second sample after volume adjustment, and generate a standard curve based on the detection results; S4. Based on the standard curve, calculate the content of trace elements in the substrate sample; The mixed standard solution contains the elements Fe, Si, Ni, K, Zr, Cr, V, Al, Cu, Co, Mg, P and Zn; The concentration gradient of each element in the mixed standard solution corresponds to the content of each element in the titanium dioxide sample.

[0020] This invention utilizes a mixed standard solution containing 13 key trace elements, including Fe, Si, Ni, K, Zr, Cr, V, Al, Cu, Co, Mg, P, and Zn, combined with ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry) technology. This enables the quantitative analysis of multiple impurities in titanium dioxide samples within a single digestion and detection process, significantly improving detection efficiency and meeting the industrial demand for rapid multi-indicator monitoring of product quality. The method employs a standard addition method (S2 step), where a calibration series (second sample) is prepared by adding mixed standard solutions of different concentrations to the dispensed sample solution (first sample). This ensures that the standard solution and the sample to be tested have the exact same matrix composition (titanium matrix and acid medium). This minimizes the suppression or enhancement effects that the complex matrix of titanium dioxide may have on the signal of the analyte, thus obtaining more accurate and reliable quantitative results than the traditional external standard method. To address the issue of incomplete digestion of titanium dioxide, this invention employs a mixed acid digestion system of hydrochloric acid, nitric acid, and hydrofluoric acid. The introduction of hydrofluoric acid, in particular, effectively destroys any silicate inclusions or insoluble substances that may exist in titanium dioxide (primarily TiO2), while ensuring the complete decomposition of the highly stable TiO2 itself. This is a crucial step in achieving complete dissolution of trace elements and avoiding low results, laying a solid foundation for subsequent accurate determination. Furthermore, this invention utilizes an ICP-OES system with a hydrofluoric acid-resistant injection system, allowing direct analysis of hydrofluoric acid-containing test solutions without the need for cumbersome and time-consuming acid removal steps. This simplifies the operation process, shortens analysis time, reduces the risk of sample contamination and loss of analytes due to transfer and heating steps, and enhances experimental safety. The concentration range of the calibration curve in this invention is scientifically set based on the expected element content in actual samples. This ensures that the method can detect titanium dioxide samples of different grades and produced using different processes within the optimal linear range, thereby guaranteeing the applicability of the method and the reliability of the measurement results in various application scenarios.

[0021] To ensure rapid and complete dissolution of titanium dioxide samples and prevent trace elements from being trapped and unable to dissolve, in some embodiments, in step S1, hydrochloric acid-nitric acid-hydrofluoric acid are used sequentially for digestion, with a volume ratio of hydrofluoric acid to nitric acid of 1:1. The digestion temperature is maintained at a gentle boil on an electric furnace, and the digestion time is 25-30 minutes. This invention optimizes the digestion system ratio, sequence, and temperature and time parameters, while considering both digestion efficiency and elemental stability, thus solving the technical challenge of difficult dissolution of titanium dioxide.

[0022] The selection of sample amount is crucial. An appropriate sample amount ensures that the intensity of the trace element detection signal meets the accuracy requirements, while avoiding incomplete digestion and increased matrix interference due to excessive sample amount, thus balancing detection sensitivity and operational feasibility. In some embodiments, in step S1, the amount of titanium dioxide sample is selected from 0.2~0.3g.

[0023] A suitable concentration of hydrochloric acid can maintain the stability of trace elements and avoid hydrolysis loss. In some embodiments, in step S2, the volume adjustment is performed using 3-6% hydrochloric acid to bring the volume to 100 ml. The 100 ml volume ensures that the element concentration is within the optimal detection range of ICP-OES, while also providing a stable matrix environment for subsequent standard curve plotting, thus improving quantitative accuracy. In some embodiments, during S3, the preset parameters of the ICP-OES instrument during detection are: RF power 1100~1200W; carrier gas flow rate 0.3~0.6L / min, carrier gas pressure 1.5~1.7bar; auxiliary gas flow rate 0.3~0.8L / min; cooler flow rate 12.0~15.0L / min; pump speed 40~55rpm. This invention is optimized for the characteristics of the titanium dioxide digest matrix and the spectral lines of the analyte, providing stable plasma, high atomization efficiency, and good signal response for simultaneous multi-element determination under hydrofluoric acid resistant conditions, ensuring detection sensitivity and precision. In some embodiments, in step S3, the elemental reference analytical lines in the ICP-OES are: P 177.495nm, Zn 202.54nm, Ni 231.6nm, Fe 238.2nm, Si 251.61nm, Mg 279.55nm, Cr 283.56nm, V 289.332nm, Zr 343.82nm, Al 396.15nm, K 766.49nm, Cu 213.598nm, and Co 238.636nm. The aforementioned analytical lines of this invention are selected to avoid spectral interference from the titanium matrix and coexisting elements, significantly reducing the impact of spectral interference on the detection results, solving the core problem of numerous interferences in trace element measurements, and improving detection accuracy.

[0024] In some embodiments, the standard addition concentration gradient of Al in S2 is 0 mg / L, 2.5 mg / L, 10.0 mg / L, 20.0 mg / L, and 40.0 mg / L; the standard addition concentration gradient of Si is 0 mg / L, 0.2 mg / L, 0.5 mg / L, 2.5 mg / L, 10.0 mg / L, and 20.0 mg / L; the standard addition concentration gradient of Zn, K, and Zr is 0 mg / L, 0.05 mg / L, 0.2 mg / L, 0.5 mg / L, 2.5 mg / L, and 10.0 mg / L; and the concentration gradient of the remaining elements is 0 mg / L, 0.01 mg / L, 0.05 mg / L, 0.2 mg / L, 0.5 mg / L, and 2.5 mg / L. This invention designs differentiated concentration gradients for different elements in titanium dioxide, which are common in the range of their content. This allows the standard curve to accurately cover the actual content of elements in the sample, avoiding quantitative deviations caused by improper gradient settings and improving the detection accuracy of low-content elements. To improve the standardization and reliability of the experiment, in some embodiments, in step S1, four 0.2g portions of titanium dioxide sample are weighed and placed in 100mL polytetrafluoroethylene (PTFE) beakers with lids. 5mL of analytical grade hydrofluoric acid and 5mL of analytical grade nitric acid are added, and the mixture is heated on an electric furnace to a gentle boil and maintained for 25-30 minutes until completely dissolved. After cooling, the portions are transferred to 100mL plastic volumetric flasks. This invention clearly defines the sample volume, container specifications, reagent specifications and volumes, standardizes the digestion operation procedure, ensures the consistency and repeatability of the digestion effect, and the PTFE material prevents the container from reacting with the reagents and contaminating the sample.

[0025] In some embodiments, in step S2, a first sample is taken as the substrate sample, and mixed standard solutions of different concentrations are added to the substrate sample and the remaining first samples, respectively. The volume is then adjusted to 100 mL with 5% hydrochloric acid, using ultrapure water for adjustment, to obtain the adjusted substrate sample and second sample. This invention uses 5% hydrochloric acid for volume adjustment with ultrapure water, ensuring matrix consistency to eliminate matrix interference and precisely controlling the volume adjustment. This allows for more accurate concentration gradient settings in the standard addition method, laying the foundation for subsequent standard curve plotting.

[0026] To improve detection results, in some embodiments, step S3 includes: based on the detection results of the substrate sample and the second sample, and based on the actual weight and fixed volume of the sample input on the ICP-OES instrument, plotting a standard curve; and after the correlation coefficient of the curve reaches 98%, initiating detection and outputting the mass percentage results of each trace element. Accurate quantitative conversion is achieved by inputting the actual weight and fixed volume; the 98% correlation coefficient requirement ensures the good fit of the standard curve; and the direct output of mass percentage results eliminates the need for additional conversion, improving detection efficiency and result accuracy, and meeting the precise requirements of quality control.

[0027] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to conventional technical solutions in the art. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0028] In this invention, the term "micro-boiling" refers to "heating until small bubbles begin to appear continuously at the edge of the liquid surface" or "heating until the liquid begins to churn continuously but does not boil violently".

[0029] In this invention, the term "partial transfer" refers to the process of digesting four 0.2g portions of titanium dioxide sample separately and then transferring each portion into a 100mL plastic volumetric flask.

[0030] Example 1 1.1 Sample digestion: Weigh 0.2g of each of the four titanium dioxide samples and place them in a 100mL polytetrafluoroethylene beaker with a lid. Add 5mL of analytical grade nitric acid and 5mL of analytical grade hydrofluoric acid in sequence. Heat on an electric furnace until it boils slightly and maintain for 30min until it is completely dissolved. After cooling, transfer the samples to 100mL plastic volumetric flasks to obtain the first sample.

[0031] 1.2 Sample preparation: Take one part of the first sample as the base sample, and add mixed standard solution (containing Fe, Si, Ni, K, Zr, Cr, V, Al, Cu, Co, Mg, P and Zn elements) of different concentrations to the base sample and the other three parts of the first sample. The standard concentration gradients for Al were 0 mg / L, 2.5 mg / L, 10.0 mg / L, 20.0 mg / L, and 40.0 mg / L; for Si, 0 mg / L, 0.2 mg / L, 0.5 mg / L, 2.5 mg / L, 10.0 mg / L, and 20.0 mg / L; for Zn, K, and Zr, 0 mg / L, 0.05 mg / L, 0.2 mg / L, 0.5 mg / L, 2.5 mg / L, and 10.0 mg / L; and for the remaining elements, 0 mg / L, 0.01 mg / L, 0.05 mg / L, 0.2 mg / L, 0.5 mg / L, and 2.5 mg / L. The solution was then diluted to 100 mL with 5% hydrochloric acid, using ultrapure water for adjustment, to obtain the final substrate sample and the second sample.

[0032] 1.3 Instrument Testing and Standard Curve Plotting: An ICP-OES system with a hydrofluoric acid-resistant injection system was prepared. Instrument parameters were set as follows: RF power 1100W, carrier gas flow rate 0.3L / min, carrier gas pressure 1.5bar, auxiliary gas flow rate 0.3L / min, cooler flow rate 12.0L / min, pump speed 40rpm. Elemental reference analytical lines were selected: P 177.495nm, Zn 202.54nm, Ni 231.6nm, Fe 238.2nm, Si 251.61nm, Mg 279.55nm, Cr 283.56nm, V 289.332nm, Zr 343.82nm, Al 396.15nm, K 766.49nm, Cu 213.598nm, Co 238.636nm. To test the substrate sample and the second sample, input the actual weight and volume of the sample into the ICP-OES instrument, plot the standard curve, and start the test after the correlation coefficient of the curve reaches 98%.

[0033] 1.4 Content Calculation: Based on the standard curve, the mass percentage content of each trace element in the substrate sample was calculated. The specific calculation method is as follows: After completing the instrument detection and obtaining the standard curve, vanadium (V) was used as an example for calculation. The vanadium spiking concentrations in the substrate sample and the three second samples were 0 mg / L, 0.01 mg / L, 0.05 mg / L, 0.2 mg / L, 0.5 mg / L, and 2.5 mg / L, respectively, and the corresponding spectral intensity response values ​​were I0, I1, I2, and I... 3、 I4, I5, I6.

[0034] Plotting the spiked concentration on the x-axis and the measured spectral intensity on the y-axis, a linear fit was performed to obtain the standard addition curve equation: I = k × C 添加 +b, where k is the slope and b is the intercept.

[0035] Extend the curve backward until it intersects the horizontal axis (i.e., spectral intensity I=0). The absolute value of the intersection point is the concentration C of vanadium in the sample solution. 样品 (mg / L). The calculation formula is: C 样品 =|-b / k|.

[0036] Based on the actual sample weight m = 0.5 g and the final volume V = 100 mL, calculate the mass percentage content of vanadium in the sample w(V): w(V)=[(C 样品 ×V) / (m×10 6 )]×100%=[(C 样品 ×0.1) / (0.5×10 6 )]×100%.

[0037] Following these steps, calculate the content of each of the remaining trace elements, such as copper (Cu), iron (Fe), and silicon (Si).

[0038] Example 2 2.1 Sample digestion: Weigh 0.2g of each of the four titanium dioxide samples and place them in a 100mL polytetrafluoroethylene beaker with a lid. Add 5mL of analytical grade nitric acid and 5mL of analytical grade hydrofluoric acid in sequence. Heat on an electric furnace until it boils slightly and maintain for 30min until it is completely dissolved. After cooling, transfer the samples to 100mL plastic volumetric flasks to obtain the first sample.

[0039] 2.2 Sample Preparation: One sample was taken as the base sample, and mixed standard solutions (containing 13 target elements) of different concentrations were added to the remaining three samples. The standard concentration gradients for Al were 0 mg / L, 2.5 mg / L, 10.0 mg / L, 20.0 mg / L, and 40.0 mg / L; for Si, 0 mg / L, 0.2 mg / L, 0.5 mg / L, 2.5 mg / L, 10.0 mg / L, and 20.0 mg / L; for Zn, K, and Zr, 0 mg / L, 0.05 mg / L, 0.2 mg / L, 0.5 mg / L, 2.5 mg / L, and 10.0 mg / L; and for the remaining elements, 0 mg / L, 0.01 mg / L, 0.05 mg / L, 0.2 mg / L, 0.5 mg / L, and 2.5 mg / L. The volume was adjusted to 100 mL with 5% hydrochloric acid and then further adjusted with ultrapure water to obtain the second sample.

[0040] 2.3 Instrument Testing and Standard Curve Plotting: Set the ICP-OES instrument parameters as follows: RF power 1150W, carrier gas flow rate 0.45L / min, carrier gas pressure 1.6bar, auxiliary gas flow rate 0.5L / min, cooler flow rate 13.5L / min, pump speed 48rpm. Select the specified element reference analysis line for detection. Input the actual sample weight and final volume, plot the standard curve (correlation coefficient ≥98%), and then start the detection.

[0041] 2.4 Content Calculation: Based on the standard curve, output and calculate the mass percentage content of each trace element in the substrate sample. For specific calculation methods, refer to Example 1.

[0042] Example 3 3.1 Sample digestion: Weigh 0.3g of titanium dioxide sample, accurate to 0.1mg, and place it in a 100mL polytetrafluoroethylene beaker with a lid. Add 3mL of nitric acid and 3mL of hydrofluoric acid (volume ratio 1:1) in sequence. Heat on an electric furnace until it boils slightly and maintain for 30min until completely dissolved. After cooling, divide it into 3 portions and transfer them to 100mL plastic volumetric flasks to obtain the first sample.

[0043] 3.2 Sample Preparation: Take one portion of the first sample as the base sample, and add mixed standard solutions to the remaining two portions respectively. The standard concentration gradients for Al are 0 mg / L, 2.5 mg / L, 10.0 mg / L, 20.0 mg / L, and 40.0 mg / L; for Si, the standard concentration gradients are 0 mg / L, 0.2 mg / L, 0.5 mg / L, 2.5 mg / L, 10.0 mg / L, and 20.0 mg / L; for Zn, K, and Zr, the standard concentration gradients are 0 mg / L, 0.05 mg / L, 0.2 mg / L, 0.5 mg / L, 2.5 mg / L, and 10.0 mg / L; and for the remaining elements, the concentration gradients are 0 mg / L, 0.01 mg / L, 0.05 mg / L, 0.2 mg / L, 0.5 mg / L, and 2.5 mg / L. The solution is then diluted to 100 ml with 3% hydrochloric acid to obtain the second sample.

[0044] 3.3 Instrument Detection and Standard Curve Plotting: Set the ICP-OES instrument parameters as follows: RF power 1200w, carrier gas flow rate 0.6L / min, carrier gas pressure 1.7bar, auxiliary gas flow rate 0.8L / min, cooler flow rate 15.0L / min, pump speed 55rpm. Select the specified element reference analysis line to detect the substrate sample and the second sample, and generate a standard curve.

[0045] 3.4 Content Calculation: Based on the standard curve, the content of each trace element in the substrate sample was calculated. For the specific calculation method, please refer to Example 1.

[0046] Example 4 4.1 Sample digestion: Weigh 0.2g of titanium dioxide sample, accurate to 0.1mg, and place it in a 300mL polytetrafluoroethylene beaker. Add 6mL of nitric acid and 6mL of hydrofluoric acid (volume ratio 1:1) in sequence. Heat on an electric furnace until it boils slightly and maintain for 30min until completely dissolved. After cooling, divide it into 4 portions and transfer them to 100mL plastic volumetric flasks to obtain the first sample.

[0047] 4.2 Sample Preparation: Take one portion of the first sample as the base sample, and add mixed standard solutions to the remaining three portions. The standard concentration gradients for Al are 0 mg / L, 2.5 mg / L, 10.0 mg / L, 20.0 mg / L, and 40.0 mg / L; for Si, the standard concentration gradients are 0 mg / L, 0.2 mg / L, 0.5 mg / L, 2.5 mg / L, 10.0 mg / L, and 20.0 mg / L; for Zn, K, and Zr, the standard concentration gradients are 0 mg / L, 0.05 mg / L, 0.2 mg / L, 0.5 mg / L, 2.5 mg / L, and 10.0 mg / L; and for the remaining elements, the concentration gradients are 0 mg / L, 0.01 mg / L, 0.05 mg / L, 0.2 mg / L, 0.5 mg / L, and 2.5 mg / L. The solution is then diluted to 100 ml with 6% hydrochloric acid to obtain the second sample.

[0048] 4.3 Instrument Testing and Standard Curve Plotting: Set the ICP-OES instrument parameters as follows: RF power 1180w, carrier gas flow rate 0.5L / min, carrier gas pressure 1.65bar, auxiliary gas flow rate 0.6L / min, cooler flow rate 14.0L / min, pump speed 50rpm, select the specified element reference analysis line for testing, and plot the standard curve.

[0049] 4.4 Content Calculation: Based on the standard curve, the content of each trace element in the substrate sample was calculated. For the specific calculation method, please refer to Example 1.

[0050] Experimental Example The accuracy, reliability, and superiority of the method of the present invention were verified through precision tests, spike recovery tests, and comparative tests with existing technologies.

[0051] 5.1 Test Samples Three groups of titanium dioxide samples from different batches were selected (numbered as Sample 1, Sample 2, and Sample 3).

[0052] Experimental instruments and reagents Instrument: ICP-OES with hydrofluoric acid resistant injection system (model: Agilent 5110); Reagents: Superior purity hydrochloric acid, nitric acid, hydrofluoric acid; single-element standard stock solutions of Fe, Si, Ni, K, Zr, Cr, V, Al, Cu, Co, Mg, P, and Zn (concentration 1000 μg / mL, National Nonferrous Metals and Electronic Materials Analysis and Testing Center); ultrapure water (resistivity ≥18.2 MΩ). cm).

[0053] 5.2 Verification Test and Results 5.2.1. Precision Test Sample 1 was subjected to six parallel tests according to the method of Example 1 of this invention, and the relative standard deviation (RSD) of the determination results of each element was calculated. The results are shown in the table below:

[0054] As shown in the table above, the RSD of the detection results of the 13 trace elements by the method of the present invention is ≤3.5%, indicating that the method has good precision and the detection results are stable and reliable.

[0055] 5.2.2. Spike Recovery Test A mixed standard solution of known concentration was added to sample 2 (the amount of each element added was 1 times the content of the corresponding element in the sample), and the detection was performed according to the method of Example 1 of this invention. The spiked recovery rate was calculated, and the results are shown in the table below:

[0056] As shown in the table above, the spiked recoveries of the 13 trace elements by the method of the present invention are between 83.3% and 98.5%, which meets the recovery rate requirements for trace analysis (80% to 120%), indicating that the method has high accuracy and can effectively avoid matrix interference and element loss.

[0057] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for detecting the trace element content in titanium dioxide, characterized in that, Includes the following steps: S1. Weigh the titanium dioxide sample, digest the titanium dioxide sample using a hydrochloric acid-nitric acid-hydrofluoric acid system to obtain the first sample, and divide the first sample into multiple portions; S2. Take one first sample as the base sample, add mixed standard solutions of different concentrations to the other first samples respectively, and make up the volume with the base sample to form the second sample and the base sample after volume adjustment; S3. Prepare an ICP-OES system with a hydrofluoric acid resistant injection system, detect the substrate sample and the second sample after volume adjustment, and generate a standard curve based on the detection results; S4. Based on the standard curve, calculate the content of trace elements in the substrate sample; The mixed standard solution contains the elements Fe, Si, Ni, K, Zr, Cr, V, Al, Cu, Co, Mg, P and Zn; The concentration gradient of each element in the mixed standard solution corresponds to the content of each element in the titanium dioxide sample.

2. The method according to claim 1, characterized in that, In step S1, hydrochloric acid, nitric acid, and hydrofluoric acid are used sequentially for digestion, with a volume ratio of hydrofluoric acid to nitric acid of 1:

1. The digestion temperature is maintained at a slight boil on an electric furnace, and the digestion time is 25-30 minutes.

3. The method according to claim 1, characterized in that, In step S1, the amount of the titanium dioxide sample is selected from 0.2~0.3g.

4. The method according to claim 3, characterized in that, In step S2, the volume is adjusted to 100 ml using 3-6% hydrochloric acid.

5. The method according to claim 3, characterized in that, In step S3, during the detection, the preset parameters of the ICP-OES instrument are: RF power 1100~1200w; carrier gas flow rate 0.3~0.6L / min, carrier gas pressure 1.5~1.7bar; auxiliary gas flow rate 0.3~0.8L / min; cooler flow rate 12.0~15.0L / min; pump speed 40~55rpm.

6. The method according to claim 5, characterized in that, In S3, the elemental reference analysis lines in the ICP-OES are: P 177.495nm, Zn 202.54nm, Ni 231.6nm, Fe 238.2nm, Si 251.61nm, Mg 279.55nm, Cr 283.56nm, V 289.332nm, Zr 343.82nm, Al 396.15nm, K 766.49nm, Cu 213.598nm, and Co 238.636nm.

7. The method according to claim 1, characterized in that, The standard addition concentration gradients of Al in S2 are 0 mg / L, 2.5 mg / L, 10.0 mg / L, 20.0 mg / L, and 40.0 mg / L; the standard addition concentration gradients of Si are 0 mg / L, 0.2 mg / L, 0.5 mg / L, 2.5 mg / L, 10.0 mg / L, and 20.0 mg / L; the standard addition concentration gradients of Zn, K, and Zr are 0 mg / L, 0.05 mg / L, 0.2 mg / L, 0.5 mg / L, 2.5 mg / L, and 10.0 mg / L; and the concentration gradients of the remaining elements are 0 mg / L, 0.01 mg / L, 0.05 mg / L, 0.2 mg / L, 0.5 mg / L, and 2.5 mg / L.

8. The method according to claim 3, characterized in that, In step S1, four 0.2g titanium dioxide samples are weighed and placed in a 100mL polytetrafluoroethylene beaker with a lid. 5mL of high-purity hydrofluoric acid and 5mL of high-purity nitric acid are added. The mixture is heated on an electric furnace until it boils slightly and is kept for 25-30 minutes until it is completely dissolved. After cooling, the samples are transferred to 100mL plastic volumetric flasks.

9. The method according to claim 8, characterized in that, In step S2, a first sample is taken as a base sample, and mixed standard solutions of different concentrations are added to the base sample and the remaining first samples respectively. The volume is adjusted to 100 mL with 5% hydrochloric acid. Ultrapure water is used to assist in adjusting the volume during the adjustment to obtain the base sample and the second sample after the volume adjustment.

10. The method according to claim 9, characterized in that, S3 includes: based on the detection results of the substrate sample and the second sample, based on the actual weighing value and fixed volume of the sample input on the ICP-OES instrument, plotting a standard curve, and after the correlation coefficient of the curve reaches 98%, starting the detection and outputting the mass percentage results of each trace element.

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