GB/T 6730.72-2016Iron ores - Determination of arsenic, chromium, cadmium, lead and mercury content - Inductively coupled plasma mass spectrometry (English PDF)

1 Scope

Part 72 of China's national series on the analysis of iron ores, determining arsenic, chromium, cadmium, lead and mercury by inductively coupled plasma mass spectrometry. These five elements are grouped for a reason that has nothing to do with metallurgy: they are the heavy metals that environmental and customs regulation cares about, and a cargo of ore has to be characterised for them whatever its iron content. ICP-MS is the right tool because it determines all five in one aspiration at the concentrations that matter, which the individual colorimetric methods elsewhere in this series cannot do without five separate preparations. Mercury is the difficult member of the set - volatile, prone to memory effects in the instrument's spray chamber, and lost during dissolution unless the digestion is closed - which is why its inclusion changes the sample preparation for all of them. This part applies to natural iron ore, iron concentrate, sinter and pellets, with the measuring range for each element given in the document.

This Part of GB/T 6730 specifies the method for the determination of arsenic, chromium, cadmium, lead, mercury in iron ore, by inductively coupled plasma mass spectrometry (ICP-MS). This Part applies to natural iron ore, iron concentrate, sinter and pellets. The measurement range is as shown in Table 1.

2 Normative references

The following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) is applicable to this standard.

GB/T 602 Chemical reagent - Preparations of standard solutions for impurity

GB/T 6379.2 Accuracy (trueness and precision) of measurement methods and results - Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method

GB/T 6682 Water for analytical laboratory use - Specification and test methods

GB/T 6730.1 Iron ores - Preparation of predried test samples for chemical analysis

GB/T 10322.1 Iron ores - Sampling and sample preparation procedures

GB/T 12806 Laboratory glassware - One-mark volumetric flasks

GB/T 12807 Laboratory glassware - Graduated pipettes

3 Principles

The sample is digested by high-temperature sealed microwave acid. The treated solution is diluted with dilute nitric acid to constant volume. The 45Sc, 72Ge, 115In, 209Bi are used as internal standards, to directly carry out ICP-MS measurement.

4 Reagents

Unless otherwise specified, the reagents for analysis shall be of superior purity or purified to the superior purity level; the water shall comply with the grade 2 water specified in GB/T 6682.

5 Instruments

5.1 General equipment and appliances Unless otherwise specified, routine laboratory equipment such as volumetric flasks and pipetting devices shall comply with Level A, which is specified in GB/T 12806 and GB/T 12807.

5.2 Inductively coupled plasma mass spectrometer For the instrument parameters and usage conditions, refer to the requirements in Appendix A. It is equipped with a hydrofluoric acid-resistant sampling system.

5.3 High temperature and pressure microwave digestion furnace Equipped with polytetrafluoroethylene (PTFE) high temperature resistant pressure sealed digestion tank (volume not more than 60 mL), its working conditions refer to the requirements in Appendix A. OR it may use other digestion equipment with the same function.

6 Sampling and specimen preparation

6.1 Laboratory specimens Specimens shall be taken and prepared in accordance with GB/T 10322.1. Generally, the specimen particle size shall be less than 100 µm. If the content of combined water or easy oxides in the specimen is high, the particle size shall be less than 160 µm.

6.2 Preparation of pre-dried specimens Thoroughly mix the laboratory specimens. Take specimens using the reduction method. Dry the specimen at 105 °C ± 2 °C, in accordance with GB/T 6730.1.

9 Test report

The test report shall include the following information:

a) Name and address of the testing laboratory;

b) Test report release date;

c) The number of this Part;

d) Necessary detailed description of the specimen itself;

e) Analytical results;

f) The number corresponding to the analytical result;