GB/T 24585-2009Ferronickel - Determination of phosphorus, manganese, chromium, copper, cobalt and silicon contents - Inductively coupled plasma atomic emission spectrometric method (English PDF)

4.8 Standard stock solution

4.8.1 Phosphorus standard solution, 1000µg/mL

Take 4.3936g of reference dipotassium hydrogen phosphate dried at 105°C ~ 110°C; dissolve it in an appropriate amount of water; transfer it into a 1000 mL volumetric flask; dilute to the mark with water; and mix evenly. 1mL of this solution contains 1000µg of phosphorus.

4.8.4 Cobalt standard solution, 1000µg/mL

Take 1.0000g of high-purity cobalt powder (content is greater than 99.9%) in a 600mL beaker; then add 40mL of nitric acid (4.5); cover with a watch glass; heat it to completely dissolve it; slightly boil to discharge nitrogen oxides; cool to room temperature; transfer to a 1000 mL volumetric flask containing 160 mL of nitric acid (4.5); dilute to the mark with water; and mix evenly. 1mL of this solution contains 1000µg of cobalt.

4.8.6 Silicon standard solution, 1000µg/mL

After the high-purity silica (content is greater than 99.9%) is sintered to its constant weight at a temperature of 1100°C, it is cooled to room temperature in a desiccator; and take 2.1393g of it into a platinum crucible; and add about 10g of anhydrous sodium carbonate; heated to melting for 15min.

4.8.7 Phosphorus standard solution, 250µg/mL

Pipette 25.00mL of phosphorus standard solution (4.8.1) in a 100mL volumetric flask; dilute to the mark with water; and mix evenly. 1mL of this solution contains 250µg of phosphorus.

4.8.8 Copper, silicon and phosphorus mixed standard solution

Pipette 25.00mL of copper standard solution (4.8.5), 50.00mL of silicon standard solution, (4.8.6) and 20.00mL of phosphorus standard solution (4.8.7), respectively in a 100mL volumetric flask; dilute to the mark with nitric acid (4.5); and mix evenly. 1mL of this solution contains copper, silicon and phosphorus of 250µg, 500µg and 50µg, respectively.

5.1 Inductively coupled plasma (ICP) spectrometer

After the spectrometer is optimized according to 7.4.1 ~ 7.4.5 and satisfies the performance indicators of 5.1.2 ~ 5.1.5, then it meets the requirements for use. The spectrometer may be either simultaneous or sequential.

5.1.1 Analysis line

This Standard does not specify a special analysis line, the recommended analysis line is listed in Table 2. When in use, carefully check the interference of the spectral lines.

5.1.4 Long-term stability

Determine the average value of the absolute intensity of the standard calibration solution with the highest concentration of each element for 3 times; and calculate the standard deviation of the 7 average values. The relative standard deviation shall be less than 2.0%.

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

Determine according to Appendix A; calculate the background equivalent concentration and detection limit, the result must be lower than the value in Table 3.

5.1.6 Linearity of the curve

Analysis Elements Wavelength / nm Possible interference spectral line / nm

7.1 Amount of testing material

Take 0.50g of testing material, accurate to 0.0001g.

7.2 Blank test

Do a blank test with the testing material. The blank test shall use pure nickel (4.1) and pure iron (4.2) equivalent to the amount of nickel and iron in the testing material to replace the testing material.

7.3 Determination

7.3.1 Preparation of testing material solution

7.3.2 Preparation of calibration curve solution

Replace the testing material with pure nickel (4.1) and pure iron (4.2) equivalent to the amount of nickel and iron in the testing material. Follow the operation procedures in 7.3.1.1. Before the final dilution to 100mL, add the standard solutions according to Table 4, then dilute to the mark with water and mix evenly.

7.4 Spectral measurement

7.4.1 Optimization of the instrument

Turn on the inductively coupled plasma (ICP) spectrometer, and run it for at least 1h before measuring.

7.4.2 Measurement of emission intensity

7.4.2.1 Measurement of calibration solution

First use the zero-concentration calibration solution; and inhale the calibration solution in order of increasing concentration; and inhale deionized water between each inhalation of the solution. Repeat the measurement for at least 2 times, and take the average of the 2 readings.

7.5 Correction of interference line in analysis line

First check the spectral interference of each coexisting element on the analysis line of the measured element.

7.6 Drawing of calibration curve

Do the linear regression with the net intensity as the Y-axis and the concentration of the measured element (µg/mL) as the X-axis. The calculation of the correlation coefficient shall meet the requirements of 5.1.6.

8.2 Correction of spectral interference

It is recommended to use synthetic standard solution as a correction method for spectral interference, the procedure is as follows. […]