GB/T 32794-2016Pig iron contenting nickel—Determination of nickel，cobalt，chromium，copper，phosphorus content—Inductively coupled plasma atomic emission spectrometry (English PDF)

4.10 Cobalt standard solution

4.10.1 Cobalt standard solution, 1 mg/mL

Weigh 1.0000 g of metallic cobalt (above 99.99%) in a 250 mL beaker. Add 40 mL of nitric acid (1 + 1). Heat to dissolve it completely. Cool to room temperature.

Transfer it into a 1 L volumetric flask. Use water to dilute it to the mark. Mix well.

1 mL of this solution contains 1 mg of cobalt.

4.10.2 Cobalt standard solution, 200 µg/mL

Pipette 20.00 mL of cobalt standard solution (4.10.1) in a 100 mL volumetric flask. Use water to dilute it to the mark. Mix well. 1 mL of this solution contains 200 µg of cobalt.

4.11 Chromium standard solution, 1 mg/mL

Weigh 2.8289 g of reference potassium dichromate (baked at 180 °C for 1 h in advance, placed in a desiccator, cooled to room temperature). Put it in a 250 mL beaker. Add appropriate amount of water to dissolve it. Transfer it into a 1 L volumetric flask. Use water to dilute it to the mark. Mix well. 1 mL of this solution contains 1 mg of chromium.

4.12 Copper standard solution

4.12.1 Copper standard solution, 1 mg/mL

Weigh 1.0000 g of pure copper (above 99.99%, stored in a desiccator at room temperature). Place it in a 250 mL beaker. Add 30 mL of nitric acid (1 + 1). Heat to dissolve it, at low temperature. Cool to room temperature. Transfer it into a 1 L volumetric flask. Use water to dilute it to the mark. Mix well. 1 mL of this solution contains 1 mg of copper.

4.12.2 Copper standard solution, 100 µg/mL

Pipette 10.00 mL of copper standard solution (4.12.1), in a 100 mL volumetric flask. Use water to dilute it to the mark. Mix well. 1 mL of this solution contains 100 µg of copper.

4.13 Phosphorus standard solution

4.13.1 Phosphorus standard solution, 1 mg/mL

Weigh 4.3940 g of reference dipotassium hydrogen phosphate (dried in advance at 105 °C to a constant amount). Place it in a 250 mL beaker. Add an appropriate amount of water to dissolve it. Transfer it into a 1 L volumetric flask.

Use water to dilute it to the mark. Mix well. 1 mL of this solution contains 1 mg of phosphorus.

4.13.2 Phosphorus standard solution, 20 µg/mL

Pipette 2.00 mL of phosphorus standard solution (4.13.1), in a 100 mL volumetric flask. Use water to dilute it to the mark. Mix well. 1 mL of this solution contains 20 µg of phosphorus.

4.14 Reagent blank stock solution

Weigh 2.5 g of ammonium fluoride. Place it in a 500 mL beaker. Add 20 mL of water and 40 mL of perchloric acid. Heat it, until white smoke is generated.

Remove and cool it. Add 50 mL of hydrochloric acid (1 + 1). Heat to boil.

Remove and cool to room temperature. Transfer it into a 500 mL volumetric flask. Use water to dilute it to the mark. Mix well.

5.1 General requirements

Initially adjust the inductively coupled plasma atomic emission spectrometer, according to the recommendations of the instrument manufacturer AND the requirements of laboratory analysis.

5.2 Actual resolution of instrument

Calculate the bandwidth of each used analysis line; the bandwidth shall be less than 0.030 nm.

5.3 Analytical spectral lines

This standard does not specify a special analysis line. The recommended analysis line is as listed in Table 2. During use, it shall check the interference of the spectral lines.

7.1 Sample amount

Weigh 0.20 g of sample, accurate to 0.0001 g.

7.2 Blank test

Pipette an iron solution (4.8), which contains similar amount of iron in the sample. Do a blank test with the sample.

7.3 Decomposition of sample

7.3.1 Place the sample (7.1) in a 250 mL polytetrafluoroethylene beaker. Add 10 mL of ammonium fluoride solution (4.7). Let it stand for 2 min ~ 3 min. Add 20 mL of nitric acid (4.3) and 10 mL of hydrochloric acid (4.2). Slowly heat to dissolve. Then add 8 mL of perchloric acid (4.4). Continue to heat, until the beaker is just filled with white smoke. Immediately remove it and cool it slightly.

Add 20 mL of water and 10 mL of hydrochloric acid (4.6). Heat to boil it. Cool it to room temperature. Transfer it into a 200 mL volumetric flask. Use water to dilute it to the mark. Mix well. Filter it under dry state.

7.3.2 If the sample is not completely dissolved, follow step of 7.3.1, until the procedure that "Add 20 mL of water and 10 mL of hydrochloric acid (4.6). Heat to boil it. Cool it to room temperature". Use medium-speed quantitative filter paper to filter it into a 200 mL volumetric flask. Use water to rinse the beaker 2 ~ 3 times. Rinse the filter paper 4 ~ 5 times. Retain the filtrate. Move the filter paper together with the residue into a platinum crucible. Ash it in a low temperature furnace at 700 °C ~ 750 °C. Take out the crucible. Cool it. Add 1 g of mixed flux (4.1). Put it in a 700 °C ~ 750 °C low temperature furnace, to melt for 20 minutes. Then move it into a 900 °C ~ 1000 °C high temperature furnace, to melt it for 5 ~ 8 minutes. Take out the crucible. Cool it. Leach it in a 250 mL glass beaker, which contains a small amount of water. Add 5 mL of hydrochloric acid (4.2). Wash the crucible clean. Heat to boil it. Cool to room temperature.

Move it into a 200 mL volumetric flask, to combine with the original filtrate. Use water to dilute it to the mark. Mix well.

7.4 Preparation of calibration curve solution

A.1 Purpose

The purpose of the performance test, which is given in this Appendix, is to use different types of instruments, to properly determine the performance of the plasma spectrometer. It allows different instruments to use different operating conditions, BUT the plasma spectrometer can ultimately produce consistent results.

The whole performance test procedure is evaluated by three basic parameters: detection limit (DL), background equivalent concentration (BEC), short-term precision (RSDN).

A.2 Definition

This standard applies the following definitions: […]

A.2.1 Detection limit (DL)

When an element produces a minimum concentration signal, it can be considered to exceed any false background signal with a certain specified level; on the other hand, the element concentration produces a signal, which is three times the standard deviation of the background level value.

A.2.2 Background equivalent concentration (BEC): It is the concentration of the analyte that produces a net intensity equal to the background intensity value; it is a measure of sensitivity to a given wavelength.

A.2.3 Short-term precision (RSDN): The relative standard deviation of a series of readings of the instrument, which is obtained under the measurement conditions.

A.3 Background equivalent concentration and detection limit

Prepare 3 sets of solution, which has the concentration of the measured substances: 0 concentration level, 10 times the detection limit, 1000 times the detection limit. These solutions contain acids and matrix elements, at similar concentrations to the tested samples.

The plasma spectrometer shall be adjusted initially, according to the manufacturer's recommendations AND the laboratory's practical experience in quantitative analysis. Absorb the blank solution AND take 10 intensity readings. […]