GB/T 20125-2006Low-alloy steel -- Determination of multi-element contents -- Inductively coupled plasma atomic emission spectrometric method (English PDF)

4.7 Yttrium standard solution

4.8 Silicon standard solution

4.8.1 Silicon stock solution, 500.0 µg/mL

Weigh 0.5348 g of silica (mass fraction greater than 99.9%, pre-fired at 1000 °C for 1 h, placed in a desiccator and cooled to room temperature). Place it in a platinum crucible, which contains 3 g of anhydrous sodium carbonate. Stir it evenly. Cover (1 ~ 2) g of anhydrous sodium carbonate on the top.

4.9 Manganese standard solution

4.9.1 Manganese stock solution, 1000.0 µg/mL

Weigh 1.0000 g of electrolytic manganese [mass fraction greater than 99.9%, use nitric acid (1 + 3) to wash the surface oxide film in advance;

4.10 Phosphorus standard solution

4.10.1 Phosphorus stock solution, 1000.0 µg/mL

Weigh 4.3936 g of standard potassium dihydrogen phosphate (KH2PO4) (pre-dried at

105 °C for 1 h. Place it in a desiccator. Cool it to room temperature). Place it in a 500 mL beaker. Use an appropriate amount of water to dissolve it. Boil it. Cool it. Transfer it into a 1000 mL volumetric flask. Use water to dilute it to the mark. Mix well.

1 mL of this solution contains 1000.0 µg of phosphorus.

4.16 Cobalt standard solution

4.17 Titanium standard solution

4.17.1 Titanium stock solution, 250.0 µg/mL

Weigh 0.2500 g of titanium metal (mass fraction greater than 99.9%). Put it in a 400 mL polytetrafluoroethylene beaker. Add 5 mL of hydrofluoric acid. Immediately add 2 mL of nitric acid (4.3) dropwise. Heat to dissolve it. Cool it. Add 20 mL of sulfuric acid (4.5). Evaporate it at low temperature, until sulfuric acid smoke. Cool to room temperature. Use sulfuric acid (5 + 95), to transfer it into a 1000 mL volumetric flask.

Use water to dilute it to the mark. Mix well.

4.18 Aluminum standard solution

4.18.1 Aluminum stock solution, 1000.0 µg/mL

Weigh 1.0000 g of pure aluminum (mass fraction greater than 99.9%). Put it in a 500 mL beaker. Add 100 mL of hydrochloric acid (1 + 1). Dissolve it on a water bath at

85 °C (1 ~ 3 days).

5.1 Inductively coupled plasma atomic emission spectrometer (ICP-AES)

If, after the spectrometer is optimized according to 7.4.1 ~ 7.4.5, it meets the performance index of 5.1.2 ~ 5.1.5, THEN, it meets the usage requirements.

Spectrometers can be either simultaneous or sequential. However, it must have the function of measuring the internal mark, at the same time. Otherwise, the internal standard method cannot be used.

5.1.4 Long-term stability

Make 3 measurements, of the average value of the absolute intensity or intensity ratio of the calibration solution, which has the highest concentration of each element.

Calculate the standard deviation of the seven average values.

5.1.5 Background equivalent concentration and detection limit (see Appendix A.2)

Elements Wavelength/nm Possible interfering elements

For the analysis line, which contains only the element to be detected in the solution, calculate the background equivalent concentration (BEC) and detection line (DL); the results must be lower than the values in Table 3.

5.1.6 Linearity of curve

The linearity of the calibration curve is checked by calculating the correlation coefficient, which must be greater than 0.999.

7.1 Sample amount

Weigh 0.50 g of sample, accurate to 0.1 mg.

7.2 Blank test (equivalent to No.0)

Weigh 0.500 g of high-purity iron (4.1). Make a blank test with the sample.

7.3 Determination

7.3.1 Preparation of specimen solution

Place the sample (7.1) in a 200 mL beaker. Add 10 mL of water, 5 mL of nitric acid (4.3).

7.3.2 Preparation of calibration curve solution

Weigh 7 parts of 0.500 g high-purity iron (4.1) into a 200 mL beaker. Dissolve it according to step 7.3.1.Cool it to room temperature. Transfer the solution to a 100 mL volumetric flask. Add the standard solution of the analyte, according to Table 4 and

Table 5.

7.4 Spectral measurements

7.4.1 Optimization of instrument

Turn on ICP-AES and run for at least 1 h, before taking measurements.

Measure the most concentrated calibration solution. Adjust the instrument parameters, according to the operating procedures and guidelines, which are provided by the instrument manufacturer. gas (outer, middle or center) flow rate, torch position, entrance slit, exit slit, photomultiplier tube voltage, analysis line wavelength in Table 2, prewash time, integration time.

7.5 Correction of interference lines in analysis lines

First check the spectral interference of each coexisting element on the analytical line of the analyte. In the case of spectral interference, obtain the spectral interference correction factor, that is, the mass fraction of the analyte, when the mass fraction of the coexisting element is 1%.

7.6 Plotting of calibration curve

Take the net intensity or net intensity ratio as the Y axis; take the concentration of the analyte (µg/mL) as the X axis, for linear regression. The calculation of the correlation factor shall meet the requirements of 5.1.6.