Method for simultaneously determining contents of trace cadmium and mercury in nuclear power stainless steel

Abstract

The invention belongs to the technical field of metal content analysis, and particularly relates to a method for simultaneously determining the content of trace cadmium and mercury in nuclear stainless steel. The method comprises the following specific steps: S1, sample treatment; s2, optimizing working parameters of the inductively coupled plasma mass spectrometry analyzer; s3, selecting a Cd measurement isotope; s4, drawing a calibration curve; the method comprises the following steps: (1) preparing a calibration curve by matching main matrixes of iron, chromium and nickel; (2) respectively adding 50 mL of water into 7 100 mL volumetric flasks, respectively adding an iron matrix solution, a chromium matrix solution, a nickel matrix solution, dilute aqua regia, a cadmium standard solution and a mercury standard solution, and diluting with ultrapure water to a scale to obtain a calibration series solution; (3) subtracting the intensity ratio in the zero standard solution from the intensity ratio of the measured element in each standard solution to obtain a net intensity ratio, and drawing a calibration curve by taking the concentration of the calibration solution as an abscissa and the net intensity ratio as an ordinate; and S5, sample determination. According to the method, the content of trace cadmium and mercury in the nuclear power stainless steel can be accurately measured at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of metal content analysis, and in particular relates to a method for simultaneously determining trace cadmium and mercury contents in nuclear power stainless steel. Background Art

[0002] With the rapid development of domestic steel smelting technology, stainless steel materials (304, 316) are widely used in the field of nuclear power. Since residual elements such as cadmium and mercury have a great influence on various properties of steel, in order to ensure the product quality of nuclear power stainless steel, the content of residual elements such as cadmium and mercury must be strictly controlled. The ug / g level is its ideal control target, which means the number of micrograms contained in each gram. At present, the methods for determining the content of cadmium and mercury in steel include atomic absorption method, atomic fluorescence method and inductively coupled plasma spectrometry. Atomic absorption method and atomic fluorescence method still have limitations in sample pretreatment, interference, sensitivity, detection efficiency, etc. Inductively coupled plasma spectrometry cannot determine trace cadmium and mercury elements due to the shortcomings of spectral interference and low sensitivity. Therefore, the above analytical methods cannot accurately determine trace cadmium and mercury in nuclear power stainless steel at the same time.

[0003] Inductively coupled plasma mass spectrometer has become the most important equipment in trace element analysis, especially suitable for the determination of trace, trace and even ultra-trace elements. However, in the determination of trace cadmium and mercury in nuclear power stainless steel, it is affected by non-mass spectrometric interferences such as instrument drift and matrix effect. In addition, argon-based ions, isobaric isotopes and polyatomic ions will produce mass spectrometric interferences when determining cadmium, which seriously affects the accuracy of the determination results. Summary of the invention

[0004] The purpose of the present invention is to provide a method for simultaneously determining the contents of trace cadmium and mercury in nuclear power stainless steel, so as to solve the problems that the prior art cannot simultaneously determine the contents of trace cadmium and mercury in nuclear power stainless steel and the accuracy and sensitivity of inductively coupled plasma mass spectrometry in determining trace chromium and mercury in nuclear power stainless steel are low.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme: A method for simultaneously determining the trace cadmium and mercury content in nuclear power stainless steel, the specific steps are as follows: S1: Sample processing Accurately weigh 0.1000g of sample into a conical flask, accurately add 4mL of aqua regia and a small amount of ultrapure water, cover with a watch glass and heat at low temperature until completely dissolved, cool to room temperature, transfer to a 100mL volumetric flask, accurately add 10mL of 10ug / L yttrium standard solution, dilute to the scale with deionized water, shake well, reduce the influence of matrix effect and salt effect, and achieve sample dissolution.

[0006] S2: Optimization of operating parameters of inductively coupled plasma mass spectrometer (1) The working parameters of the inductively coupled plasma mass spectrometer directly affect the sensitivity and precision of the measurement. Before the measurement, the instrument's Tuning and Optimize programs were used to optimize the instrument's operating parameters such as carrier gas flow, cooling gas flow, auxiliary gas flow, RF power, and collision gas flow using a 10 ppb mixed solution of Mg, In, Ba, Ce, and U. (2) Optimize instrument operating parameters Cadmium is interfered by polyatomic ions and needs to be determined using the KED mode. Helium is used as the collision gas. While continuously changing the gas flow rate, the signal response of a certain element in the matrix is ​​first read, and then the signal response of this element after the matrix is ​​spiked is read. After obtaining two curves of signal values ​​changing with gas flow rates, the instrument's built-in reaction cell parameter optimization function is used to calculate the ratio before and after the spike. The highest point is the optimal collision gas flow rate. The final main operating parameters of the instrument are as follows: Carrier gas flow rate: 0.75~0.90L / min; Auxiliary gas flow rate: 0.60~0.80L / min; Excitation power: 1200~1400W; Helium flow rate: 3.0~4.5mL / min.

[0007] S3: Selection of isotopes for Cd measurement (1) Cause 106 The determination result of Cd was not ideal, so we re-selected the cadmium isotope with higher abundance for analysis. The only Cd isotope with less interference and higher abundance was 111 Cd (12.5%), 114 Cd (28.7%), 114 Sn pair 114 The interference of Cd determination is strong, so theoretically, 111 Cd is the best isotope to be measured, only reducing the oxide ion 95 Mo 16 O's interference is enough; (2) Molybdenum oxide ions have good chemical stability. The interference intensity of molybdenum oxide ions can be significantly reduced by optimizing instrument working parameters such as atomization gas flow rate and high-frequency power, but it cannot be completely reduced. After mathematical correction using the interference correction equation, the standard working curve of Cd was re-established for determination.

[0008] S4: Calibration curve drawing (1) Inductively coupled plasma atomic emission spectrometry is used to perform semi-quantitative scanning on samples of unknown exact composition to obtain the approximate content of iron, chromium, nickel and other metal elements in the samples. The calibration curve is prepared by matching the main matrix (iron, chromium and nickel); (2) Add 50 mL of water to seven 100 mL volumetric flasks, respectively, and add iron matrix solution, chromium matrix solution, nickel matrix solution, dilute aqua regia, cadmium standard solution and mercury standard solution, respectively. Dilute to the mark with ultrapure water and mix well to obtain a series of calibration solutions. (3) On an inductively coupled plasma mass spectrometer, select cadmium with a mass number of 110.9042, mercury with a mass number of 200.9703, and yttrium with a mass number of 88.9059. Measure the isotope signal intensity ratios of the analyte and the internal standard element in the calibration series solutions in order of concentration from low to high. Subtract the intensity ratio of the analyte in the zero standard solution from the intensity ratio of the analyte in each standard solution to obtain the net intensity ratio. Perform a linear regression with the concentration of the calibration solution as the abscissa and the net intensity ratio as the ordinate. The linearity of the calibration curve is checked by calculating the correlation coefficient, which must be greater than 0.999.

[0009] S5: Sample measurement On the inductively coupled plasma mass spectrometer, a cadmium mass number of 110.9042, a mercury mass number of 200.9703, and a yttrium mass number of 88.9059 were selected, and the blank solution and the sample solution were measured. The intensity ratio of the measured element to the internal standard element in each sample solution was subtracted from the intensity ratio of the measured element to the internal standard element in the blank solution to obtain a net intensity ratio; according to the calibration curve in step S4, the net intensity ratio of the measured element in the sample was converted into its corresponding concentration value.

[0010] Preferably, in step S1, for samples containing high contents of niobium, tungsten, hafnium, tantalum and zirconium, after the reaction of hydrochloric acid / nitric acid with the sample is completed, 1-3 mL of hydrogen peroxide is added dropwise, heated at low temperature, and the solution is heated after the sample is completely dissolved to drive out the hydrogen peroxide in the solution.

[0011] Preferably, the helium flow rate in step S2 (2) is 3 mL / min or 4 mL / min.

[0012] Preferably, the correction equation for cadmium in step S3 (1) is: 111 Cd=111 总强度 -1.073 (108 总强度 -0.712*106 总强度 ) (For nuclear power stainless steel samples, the interference coefficient 1.073 should be corrected before use in different laboratory equipment to determine a new coefficient).

[0013] Preferably, in step S4 (2), the calibration series solutions match the iron, chromium and nickel matrices, and the matching ratios are 70%, 20% and 10% respectively.

[0014] Preferably, the concentrations of the cadmium and mercury calibration solutions of different concentrations in step S4 (2) are 0-100 ng / mL and 0-10 ng / mL, respectively.

[0015] Preferably, the step S4 (3) uses an internal standard to calibrate the detection process, and the internal standard is a yttrium standard solution with a concentration of 10 ng / mL.

[0016] Preferably, the blank solution in step S5 is a 4% by volume aqueous regia solution.

[0017] Principle: Calibration curves are made with a series of cadmium and mercury standard solutions that match the sample matrix iron, chromium, and nickel. Collision reaction cell-inductively coupled plasma mass spectrometry is used to calibrate the sample with the internal standard element yttrium. The interference of molybdenum oxide ions on cadmium is corrected by the collision reaction between high-purity helium and polyatomic ions and the interference correction equation, which minimizes the influence of mass spectral interference and non-mass spectral interference on the determination of trace cadmium and mercury content in nuclear power stainless steel.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The sample processing process simplifies the dissolution and separation process, reduces reagent consumption, shortens the analysis cycle, saves manpower and material resources, reduces analysis costs, and reduces environmental pollution; (2) According to the characteristics of inductively coupled plasma mass spectrometer, a standard solution with strict matrix matching was used to make the calibration curve. At the same time, internal standard elements were added to compensate for instrument drift and matrix effects. The collision reaction between high-purity helium and polyatomic ions and the interference correction equation were used to correct the interference of molybdenum oxide ions on cadmium, thereby achieving simultaneous and accurate determination of trace cadmium and mercury contents in nuclear power stainless steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a calibration curve diagram for measuring cadmium in the present invention; Figure 2 This is a calibration curve diagram for determining mercury in the present invention. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is described clearly and completely below in conjunction with the embodiments and drawings.

[0021] A method for simultaneously determining the trace cadmium and mercury content in nuclear power stainless steel, the specific steps are as follows: S1: Sample processing Accurately weigh 0.1000g of sample into a conical flask, add 4mL of aqua regia and a small amount of ultrapure water, cover with a watch glass and heat at low temperature until completely dissolved, cool to room temperature, transfer to a 100mL volumetric flask, accurately add 10mL of 10ug / L yttrium standard solution, dilute with deionized water, make up to 100mL and shake well.

[0022] S2: Optimization of operating parameters of inductively coupled plasma mass spectrometer Using the Tuning and Optimize programs set in the instrument, a 10 ppb mixed solution of Mg, In, Ba, Ce, and U was used to optimize the instrument's operating parameters, including carrier gas flow, cooling gas flow, auxiliary gas flow, lens voltage, and RF power. Cadmium is interfered by polyatomic ions and needs to be determined using the KED mode. Helium is used as the collision gas. While continuously changing the gas flow rate, the signal response of a certain element in the matrix is ​​first read, and then the signal response of this element after the matrix is ​​spiked is read. After obtaining two curves of signal values ​​changing with gas flow rates, the reaction cell parameter optimization function of the instrument is used to calculate the ratio before and after the addition of the spike. The highest point is the optimal collision gas flow rate. The polyatomic ion interference removal rates of elements such as cadmium and mercury are better when the helium flow rate is 3.0 and 4.0 mL / min, respectively. If different helium flow rates are used for each element, the switching time will significantly increase the measurement time of a single sample, reducing the detection efficiency. Taking comprehensive considerations, the instrument operating parameters were selected for the experiment: power of 1300 W, auxiliary gas flow of 0.8 L / min, carrier gas flow of 0.90 L / min, lens voltage of 7.5 V, sampling cone aperture of 1.1 mm (nickel cone), intercepting cone aperture of 0.9 mm (nickel cone), and the counting rate of the internal standard Y was controlled at 10 5 Count / s or so.

[0023] S3: Selection of isotopes for Cd measurement use 111 The correction equation for Cd is: 111 M-1.073×[ 108 M-0.712×( 106 M)], used for correction 95 Mo 16 O interference, the equation is calculated from the natural abundance ratio between isotopes. 95 Mo 16 The interference intensity of O on the interfered 111 Cd is corrected; The derivation process is as follows: 111Total Strength = 111 Cd+ 95 Mo 16 O; 95 Mo 16 O=111total intensity-111Cd··············① 92 Mo 16 O=108 total intensity-108Cd··············② ① / ②=15.92% / 14.84%=1.073, that is, 95 Mo 16O = 1.073 × (108 total intensity - 108 Cd); 108 Cd = ( 108 Cd / 106 Cd) × 106 total intensity = (0.89% / 1.25%) × 106 total intensity = 0.712 × 106 total intensity; so, 111 Cd = 111 total intensity - 1.073 × [108 total intensity - 0.712 × 106 total intensity]; From the calculation process of the equation, we can know that 111 CD is subject to 95 Mo 16 O interference, through the mass number 108 92 Mo 16 Indirect calculation 95 The oxide of Mo interferes with the contribution of 108 Cd is composed of 106 Cd is calculated and deducted indirectly; The applicability of this equation is better in matrices with low Mo content, while the Mo content in nuclear power stainless steel is often as high as 1% to 3.5%. 108 Cd (0.89%) and 106 The abundance ratio of Cd (1.25%) is extremely low, and the oxide ion of Mo is 108 The interference intensity of Cd is 10 to 20 times that of other isotopes of cadmium. Therefore, when the molybdenum content in nuclear power stainless steel is high and the cadmium content is low, the results will inevitably deviate to a certain extent when the correction equation is used for determination. Therefore, the correction formula must be corrected. Select a national standard substance of nickel-based high-temperature alloy (GBW01639) that does not contain cadmium, digest several portions according to the method, prepare sample solutions containing cadmium of 1.00μg / L, 5.00μg / L, and 10.00μg / L, and write 111 Cd = 111 total intensity - 1.073 × [108 total intensity - 0.712 × 106 total intensity], the measured results were fitted with the theoretical values, and the results are shown in Table 1;

[0024] The corrected calibration formula in Table 1 was written into the instrument program, and the national standard material of nickel-based high-temperature alloy containing cadmium was measured. The verification and comparison results are shown in Table 2;

[0025] Experiments show that the measured values ​​of trace cadmium in nickel-based high-temperature alloys using the modified mathematical formula correction method are consistent with the certified values, with good recovery and good accuracy.

[0026] S4: Calibration curve drawing (1) Inductively coupled plasma atomic emission spectrometry is used to perform semi-quantitative scanning on samples of unknown exact composition to obtain the approximate content of iron, chromium, nickel and other metal elements in the sample. The calibration curve is prepared by matching the main matrix iron, chromium and nickel; (2) Add about 50 mL of water to seven 100 mL volumetric flasks respectively, add iron matrix solution, chromium matrix solution, nickel matrix solution, aqua regia, cadmium standard solution and mercury standard solution according to the contents in Table 3, dilute to the scale with ultrapure water, mix well, and obtain a series of calibration solutions; Table 3 Cadmium and mercury calibration blank solutions and calibration solutions

[0027] (3) On the inductively coupled plasma mass spectrometer, select cadmium mass number 110.9042, mercury mass number 200.9703 and yttrium mass number 88.9059, and measure the isotope signal intensity ratio of the element to be measured and the internal standard element in the calibration series solution in order of concentration from low to high. Subtract the intensity ratio of the element to be measured in each standard solution from the intensity ratio of the zero standard solution to obtain the net intensity ratio. Linear regression is performed with the concentration of the calibration solution as the horizontal axis and the net intensity ratio as the vertical axis, and the following is obtained: Figure 1 Calibration curve for cadmium and Figure 2 Calibration curve plot for mercury.

[0028] S5: Sample measurement On the inductively coupled plasma mass spectrometer, the mass number of cadmium is 110.9042, the mass number of mercury is 200.9703, and the mass number of yttrium is 88.9059. The blank solution and the sample solution are measured, and the intensity ratio of the measured element and the internal standard element in each sample solution is subtracted from the intensity ratio of the measured element and the internal standard element in the blank solution to obtain a net intensity ratio. According to the calibration curve in step S4, the net intensity ratio of the measured element in the sample is converted into its corresponding concentration value.

[0029] S6: Accuracy and Precision In order to verify the measurement accuracy and reliability of this method, standard samples were selected: iron-nickel-based superalloy (GBW01619), iron-nickel-based superalloy (GBW01621), and iron-nickel-based superalloy (GBW01623) for accuracy experiments. Due to the special properties of mercury, it is difficult for mercury to remain in steel. Therefore, mercury cannot be detected in each standard substance. In view of this situation, when conducting the accuracy experiment of mercury, the mercury standard solution was added for determination. The mercury standard solution was added to the nuclear power stainless steel (YSBC15342-2008) standard sample solution. After the addition, the mass percentage of mercury was 0.0005%, which is nuclear power stainless steel 1#. The mercury standard solution was added to the nuclear power stainless steel (YSBC15345-2008) standard sample solution. After the addition, the mass percentage of mercury was 0.0010%, which is nuclear power stainless steel 2#. In addition, considering the lack of high-content cadmium standard samples, the test adopted the method of adding cadmium standard solution to verify the high-content cadmium. The cadmium standard solution was added to the nuclear power stainless steel (YSBC15342-2008) standard sample (Cd<0.0001%) solution. The mass percentage of cadmium after the addition was 0.0050%, which is nuclear power stainless steel 3#. The cadmium standard solution was added to the nuclear power stainless steel (YSBC15345-2008) standard sample solution. The mass percentage of cadmium after the addition was 0.010%, which is nuclear power stainless steel 4#. All test data are shown in Table 4.

[0030]

[0031] From the data in Table 4, it can be seen that the difference between the determination results of this method and the given reference values ​​of the standard substances is small, indicating that this method has high accuracy and can accurately determine the contents of zinc, selenium, cadmium and mercury in nuclear power stainless steel samples.

[0032] Samples were dissolved according to this method, and precision experiments were carried out on standard samples: iron-nickel based high temperature alloy (GBW01620), iron-nickel based high temperature alloy (GBW01622), nuclear power stainless steel 5# (304) and nuclear power stainless steel 6# (316). Nuclear power stainless steel 5# was added with a mercury standard solution equivalent to 0.0002% by mass and a cadmium standard solution equivalent to 0.0050% by mass, and nuclear power stainless steel 6# was added with a mercury standard solution equivalent to 0.0005% by mass and a cadmium standard solution equivalent to 0.010% by mass. Each sample was measured 10 times, and the average value, standard deviation and relative standard deviation of the 10 measurements were calculated. The specific data are shown in Table 5-8.

[0033]

[0034]

[0035]

[0036]

[0037] It can be seen from the data in Tables 5-8 that the relative standard deviations of the above precision experimental data are all less than 20%. For the determination of trace elements, this method has high precision.

Claims

1. A method for simultaneously determining trace cadmium and mercury content in nuclear power stainless steel, characterized in that: The specific steps are as follows: S1: Sample processing Accurately weigh 0.1000g of sample in a conical flask, accurately add 4mL of aqua regia and a small amount of ultrapure water, cover with a watch glass and heat at low temperature until completely dissolved, cool to room temperature, transfer to a 100mL volumetric flask, accurately add 10mL of 10ug / L yttrium standard solution, dilute to the scale with deionized water, shake well, reduce the influence of matrix effect and salt effect, and achieve sample dissolution; S2: Optimization of operating parameters of inductively coupled plasma mass spectrometer (1) The working parameters of the inductively coupled plasma mass spectrometer directly affect the sensitivity and precision of the measurement. Before the measurement, the instrument's Tuning and Optimize programs were used to optimize the instrument's operating parameters such as carrier gas flow, cooling gas flow, auxiliary gas flow, RF power, and collision gas flow using a 10 ppb mixed solution of Mg, In, Ba, Ce, and U. (2) Optimize instrument operating parameters Cadmium is interfered by polyatomic ions and needs to be determined using the KED mode. Helium is used as the collision gas. While continuously changing the gas flow rate, the signal response of a certain element in the matrix is ​​first read, and then the signal response of this element after the matrix is ​​spiked is read. After obtaining two curves of signal values ​​changing with gas flow rates, the instrument's built-in reaction cell parameter optimization function is used to calculate the ratio before and after the spike. The highest point is the optimal collision gas flow rate. The final main operating parameters of the instrument are as follows: Carrier gas flow rate: 0.75~0.90L / min; Auxiliary gas flow rate: 0.60~0.80L / min; Excitation power: 1200~1400W; Helium flow rate: 3.0~4.5mL / min; S3: Selection of isotopes for Cd measurement (1) Cause 106 The determination result of Cd was not ideal, so we re-selected the cadmium isotope with higher abundance for analysis. The only Cd isotope with less interference and higher abundance was 111 Cd (12.5%), 114 Cd (28.7%), 114 Sn pair 114 The interference of Cd determination is strong, so theoretically, 111 Cd is the best isotope to be measured, only reducing the oxide ion 95 Mo 16 O's interference is enough; (2) Molybdenum oxide ions have good chemical stability. The interference intensity of molybdenum oxide ions can be significantly reduced by optimizing instrument working parameters such as atomizing gas flow rate and high-frequency power, but it cannot be completely reduced. After mathematical correction using the interference correction equation, the standard working curve of Cd is re-established for determination. S4: Calibration curve drawing (1) Inductively coupled plasma atomic emission spectrometry is used to perform semi-quantitative scanning on samples of unknown exact composition to obtain the approximate content of iron, chromium, nickel and other metal elements in the samples. The calibration curve is prepared by matching the main matrix (iron, chromium and nickel); (2) Add 50 mL of water to seven 100 mL volumetric flasks, respectively, and add iron matrix solution, chromium matrix solution, nickel matrix solution, dilute aqua regia, cadmium standard solution and mercury standard solution, respectively. Dilute to the mark with ultrapure water and mix well to obtain a series of calibration solutions. (3) On an inductively coupled plasma mass spectrometer, select cadmium mass number 110.9042, mercury mass number 200.9703 and yttrium mass number 88.9059, and measure the isotope signal intensity ratios of the element to be measured and the internal standard element in the calibration series solutions in order of concentration from low to high. Subtract the intensity ratio of the element to be measured in each standard solution from the intensity ratio of the zero standard solution to obtain the net intensity ratio. Perform a linear regression with the concentration of the calibration solution as the abscissa and the net intensity ratio as the ordinate. The linearity of the calibration curve is checked by calculating the correlation coefficient, which must be greater than 0.

999. S5: Sample measurement On the inductively coupled plasma mass spectrometer, a cadmium mass number of 110.9042, a mercury mass number of 200.9703, and a yttrium mass number of 88.9059 were selected, and the blank solution and the sample solution were measured. The intensity ratio of the measured element to the internal standard element in each sample solution was subtracted from the intensity ratio of the measured element to the internal standard element in the blank solution to obtain a net intensity ratio; according to the calibration curve in step S4, the net intensity ratio of the measured element in the sample was converted into its corresponding concentration value.

2. The method for simultaneously determining the trace cadmium and mercury content in nuclear power stainless steel according to claim 1, characterized in that: In step S1, for samples containing high contents of niobium, tungsten, hafnium, tantalum and zirconium, after the reaction of hydrochloric acid / nitric acid with the sample is completed, 1-3 mL of hydrogen peroxide is added dropwise, heated at low temperature, and the solution is heated after the sample is completely dissolved to drive out the hydrogen peroxide in the solution.

3. A method for simultaneously determining trace cadmium and mercury content in nuclear power stainless steel according to any one of claims 1 or 2, characterized in that: In step S2 (2), the helium flow rate is 3 mL / min or 4 mL / min.

4. The method for simultaneously determining the trace cadmium and mercury content in nuclear power stainless steel according to claim 3, characterized in that: The correction equation for cadmium in step S3 (1) is: 111 Cd=111 总强度 -1.073 (108 总强度 -0.712*106 总强度 ), for nuclear power stainless steel samples, the interference coefficient 1.073 should be corrected before using different laboratory equipment to determine the new coefficient.

5. The method for simultaneously determining the trace cadmium and mercury content in nuclear power stainless steel according to claim 4, characterized in that: In step S4 (2), the calibration series solutions match the iron, chromium and nickel matrices, and the matching ratios are 70%, 20% and 10% respectively.

6. The method for simultaneously determining the trace cadmium and mercury content in nuclear power stainless steel according to claim 5, characterized in that: The concentrations of the cadmium and mercury calibration solutions of different concentrations in step S4 (2) are 0-100 ng / mL and 0-10 ng / mL, respectively.

7. The method for simultaneously determining the trace cadmium and mercury content in nuclear power stainless steel according to claim 6, characterized in that: The step S4 (3) uses an internal standard to calibrate the detection process, and the internal standard is a yttrium standard solution with a concentration of 10 ng / mL.

8. The method for simultaneously determining the trace cadmium and mercury content in nuclear power stainless steel according to claim 7, characterized in that: The blank solution in step S5 is a 4% by volume aqueous regia solution.

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