GB/T 20127.3-2026Steel and alloys - Determination of trace element contents - Part 3: Determination of scandium and barium by inductively coupled plasma atomic emission spectrometry (English PDF)

5.6 Hydrochloric acid-nitric acid mixture (3 1)

5.7 Strontium internal standard solution (50 µg/mL) Weigh 0.1208 g of strontium nitrate (mass fraction greater than 99.99%) (pre-stored in a desiccator for at least 24 hours), and place it in a 500 mL container. In a beaker, add water to dissolve the precipitate, boil, cool to room temperature, transfer to a 1000mL volumetric flask, dilute with water to the mark, and mix well. This solution contains 50 µg of strontium per mL and should be prepared fresh before use. Alternatively, certified standard solutions can be purchased directly.

5.8 Strontium internal standard solution (0.5 µg/mL) Transfer

1.0 mL of strontium internal standard solution (5.7) into a 100 mL volumetric flask, dilute with water to the mark, and mix well. This solution contains 0.5 µg of strontium per mL and should be prepared fresh before use.

5.9 Scandium standard solution (1000 µg/mL) Weigh 1.5338g of scandium trioxide (mass fraction >= 99.99%) that has been pre-calcined at 800°C for 1 hour and cooled to room temperature. Place in a 500mL beaker, add 100mL of nitric acid (5.4), and add hydrogen peroxide dropwise until completely dissolved. Then boil to remove all hydrogen peroxide, and cool. Transfer to a 1000mL volumetric flask, add 100mL of nitric acid (5.4), dilute with water to the mark, and mix well. This scandium standard solution contains 1000 µg of scandium per mL. Certified standard solutions can also be purchased directly.

5.10 Scandium standard solution A (100 µg/mL) Transfer

10.0 mL of scandium standard solution (5.9) into a 100 mL volumetric flask, dilute with water to the mark, and mix well. This solution contains 100 µg scandium per mL. Prepare fresh before use.

5.11 Scandium standard solution B (10 µg/mL) Transfer

10.0 mL of scandium standard solution A (5.10) into a 100 mL volumetric flask, dilute with water to the mark, and mix well. This solution contains 10 µg scandium per mL. Prepare fresh before use.

5.12 Scandium standard solution C (1 µg/mL) Transfer

10.0 mL of scandium standard solution B (5.11) into a 100 mL volumetric flask, dilute with water to the mark, and mix well. This solution contains 1 µg scandium per 1 mL. Prepare fresh before use.

5.13 Barium standard solution (1000 µg/mL) Weigh 1.4372 g of barium carbonate (mass fraction > 99.99%) (pre-dried at 105°C for 2 hours, placed in a desiccator, and cooled to room temperature). In a 500mL beaker, moisten with water, add 100mL of hydrochloric acid (5.2), heat to dissolve, cool to room temperature, and transfer to a 1000mL volumetric flask. Dilute with water to the mark and mix well. This solution contains 1000 µg of barium per mL. Alternatively, certified standard solutions can be purchased directly.

5.14 Barium Standard Solution A (50 µg/mL) Transfer

10.0 mL of barium standard solution (5.13) to a.200 mL volumetric flask, add 20 mL of hydrochloric acid (5.1), and dilute with water to the mark. Temperature. Mix well. This solution contains 50 µg of barium per mL. Prepare fresh before use.

5.15 Barium Standard Solution B (2.5 µg/mL) Transfer

5.0 mL of barium standard solution A (5.14) into a 100 mL volumetric flask, dilute with water to the mark, and mix well. This solution contains 2.5 µg of barium per mL. Prepare fresh before use.

6.2 Inductively Coupled Plasma Emission Spectrometer

6.2.1 General Requirements Inductively coupled plasma atomic emission spectrometers (ICP-AES) can be either sequential or simultaneous measurement types. If the measurement is sequential... If the instrument is equipped with a component that simultaneously measures the internal standard line, then the internal standard technique can be used; otherwise, the internal standard method cannot be used. The inductively coupled plasma atomic emission spectrometer used, after optimization (specific optimization steps conform to Appendix A), should meet the requirements of

6.2.3 to 6.2.6. The performance metrics provided.

6.2.2 Analysis Line This document does not specify any particular analytical lines; recommended analytical lines are listed in Table 1.

6.2.3 Resolution Calculate the spectral bandwidth for the selected analytical line and internal standard line; this bandwidth should be less than

0.030 nm.

6.2.4 Minimum Short-Term Precision The emission spectrum of the calibration solution at the maximum concentration of the analyte was measured 10 times within a short period of time, determining its standard value. The quasi-deviation should not exceed 0.5% of the absolute or relative average light intensity.

6.2.5 Background equivalent concentration and limit of detection Calculate the background equivalent concentration (BEC) and limit of detection (LOD) in the solution containing only the analyte element. The calculated results should be lower than those given in Table 2. Numerical value.

6.2.6 Linearity of the Calibration Curve The correlation coefficient of the calibration curve should not be less than 0.995.

7.Taking samples Samples shall be prepared in accordance with GB/T 20066 or appropriate national standards.

8.1 Scandium with a mass fraction of 0.0002% to 0.010%

8.1.1 Sample Weigh 0.50g of the sample, accurate to 1mg.

8.1.2 Blank Test Since the reagent amounts added when preparing the calibration curve solution and the sample solution are exactly the same, a blank experiment is not required in this section. Subtracting the blank value will... This can cause errors in the results.

8.1.3 Sample processing Place the sample (8.1.1) in a 100 mL beaker, add 10 mL of hydrochloric acid-nitric acid mixture (5.5), and then heat on a low-temperature electric furnace to dissolve. Solution. After the sample has dissolved, remove it and cool it. Transfer it to a 50 mL volumetric flask, dilute it with water to the mark, and mix well.

8.1.4 Spectral Measurement

8.1.4.1 Instrument Preparation Start the inductively coupled plasma atomic emission spectrometer and allow it to warm up for at least 1 hour before measurement. Optimize the instrument according to the instruction manual. After the instrument stabilizes, the scandium analytical spectral line is selected.

8.1.4.2 Calibration Curve Weigh five parallel samples (8.1.1) that are similar in composition to the sample matrix and do not contain scandium, place them in a 100 mL beaker, and add 10 mL of hydrochloric acid. Mix nitric acid with acid (5.5), then heat on a low-temperature electric furnace to dissolve. After the sample is dissolved, remove it, cool it, and transfer it to a 50 mL volumetric flask. Transfer

5.0 mL of scandium standard solution C (5.12) and

5.0 mL of scandium standard solution B (5.11) to a 50 mL volumetric diaphragm, respectively. Dilute with water to the mark in the bottle and mix well. The analytical spectral intensities of scandium in the standard solution were measured from low to high. The mass concentration of scandium was plotted on the x-axis (µg/mL), and the concentration of the standard solution was plotted on the y-axis. Plot the calibration curve with spectral line intensity as the ordinate. In standard solutions, if coexisting elements other than the analyte (such as tungsten) affect the luminescence intensity of the analyte, the calibration curve series of solutions will be affected. The amount of this coexisting element in the solution should be the same, and the same amount of this coexisting element should be added to the sample solution as to the calibration curve series solutions.

8.1.4.3 Sample Measurement The intensity of the emitted light from the scandium analytical line was obtained by measuring the test solution, and the concentration of scandium was found from the calibration curve.

8.1.5 Correction of Interference Lines in the Analysis Line First, check the spectral interference of each coexisting element on the analytical lines of the analyte. If spectral interference exists, calculate the spectral interference correction coefficient. That is, the mass fraction of the analytical element equivalent to a mass fraction of 1% of the coexisting elements.

8.2 Barium with a mass fraction of 0.001% to 0.010%

8.2.1 Sample Weigh approximately 0.25g of the sample, accurate to 1mg.

8.2.2 Blank Test A blank test was performed along with the sample.

8.2.3 Sample processing The sample (8.2.1) was placed in a 100 mL quartz beaker, and 5 mL of hydrochloric acid-nitric acid mixture (5.6) was added. The sample was then slowly heated on a low-temperature hot plate. Dissolve. After the sample has completely dissolved, remove it from the container, cool it to room temperature, transfer it to a 50 mL volumetric flask, and add

5.0 mL of strontium internal standard solution (5.8). Dilute with water to the mark and mix well. After standing and clarifying, take a sample of the supernatant for measurement. It is best to process and measure the calibration solution and test solution on the same day. It is advisable to leave it overnight.

8.2.4 Spectral Measurement

8.2.4.1 Instrument Preparation Start the inductively coupled plasma atomic emission spectrometer and allow it to warm up for at least 1 hour before measurement. Optimize the instrument according to the instruction manual. After the instrument stabilizes, measurements are taken in order of increasing barium concentration, and the intensity ratio of the barium analysis line to the internal standard strontium reference line is measured.

8.2.4.2 Calibration Curve Transfer 0 mL,

0.50 mL,

10.00 mL of barium standard solution B (5.15) into 50 mL volumetric flasks, respectively. Do not add

5.0 mL of strontium internal standard solution (5.8), dilute with water to the mark, and mix well. The intensity ratio of the barium analytical line to the internal standard strontium reference line in the calibration curve solution was measured in ascending order. The result was expressed as the mass concentration of barium. The calibration curve was plotted with (µg/mL) on the x-axis and the intensity ratio of the barium analysis line to the internal standard strontium reference line on the y-axis.

8.2.4.3 Sample Measurement The intensity ratio of the barium analytical line to the internal standard strontium reference line was obtained by measuring the test solution, and the concentration of barium was found from the calibration curve.