GB/T 6730.81-2020 PDF English
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Iron ores - Determination of multiple trace elements - Inductively coupled plasma mass spectrometric method
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GB/T 6730.81-2020: PDF in English (GBT 6730.81-2020) GB/T 6730.81-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 73.060.10
D 31
GB/T 6730.81-2020
Iron ores - Determination of multiple trace elements -
Inductively coupled plasma mass spectrometric method
ISSUED ON: JUNE 02, 2020
IMPLEMENTED ON: DECEMBER 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 5
3 Principle ... 6
4 Reagents and materials ... 6
5 Instruments ... 8
6 Sampling and sample preparation ... 8
7 Analysis steps ... 9
8 Result calculation and representation ... 10
9 Test report ... 13
Annex A (informative) Working parameters of inductively coupled plasma mass
spectrometer and determination masses of elements to be determined and internal
standard elements ... 14
Annex B (informative) Working parameters of microwave digestion instrument ... 15
Annex C (normative) Procedure for acceptance of sample analysis results ... 16
Iron ores - Determination of multiple trace elements -
Inductively coupled plasma mass spectrometric method
WARNING -- Personnel using this document shall have regular laboratory work
experience. This document does not point out all possible safety issues. It is the
user’s responsibility to take appropriate safety and health measures and ensure
compliance with the conditions specified in relevant national regulations.
1 Scope
This Part of GB/T 6730 specifies the method for determining the content of multiple
trace elements in iron ores by inductively coupled plasma mass spectrometric method.
This Part applies to the determination of the content of lead, cadmium, arsenic, mercury,
barium, cobalt, thallium, molybdenum, yttrium, lanthanum, cerium, praseodymium,
neodymium, samarium, europium, gadolinium, dysprosium, holmium, erbium, thulium,
ytterbium elements in iron ores. The determination range is shown in Table 1.
GB/T 8170 Rules of rounding off for numerical values & expression and judgement
of limiting values
GB/T 10322.1 Iron ores - Sampling and sample preparation procedures
GB/T 12806 Laboratory glassware - One-mark volumetric flasks
3 Principle
After microwave digestion, the sample is introduced into an inductively coupled plasma
mass spectrometer for determination. Use on-line internal standard, and carry out
quantitative analysis on the basis that the intensity ratio of the mass spectrum signal of
the element to be determined to the mass spectrum signal of the internal standard
element is proportional to the concentration of the element to be determined.
4 Reagents and materials
Unless otherwise stated, only approved guaranteed reagents and secondary water
complying with GB/T 6682 or water equivalent to its purity are used in the analysis.
4.1 Hydrochloric acid, ρ is about 1.19 g/mL.
4.2 Hydrofluoric acid, ρ is about 1.30 g/mL.
4.3 Nitric acid, ρ is about 1.42 g/mL.
4.4 Nitric acid, 2 + 98. TAKE an appropriate amount of nitric acid (see 4.3) and water,
MIX them in a volume ratio of 2:98.
4.5 Lead, cadmium, arsenic, mercury, barium, cobalt, thallium, molybdenum, yttrium,
lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium,
dysprosium, holmium, erbium, thulium, ytterbium standard stock solutions (1000
μg/mL): PREPARE according to GB/T 602 or use certified standard solutions.
4.6 Series of standard solutions: USE the standard stock solutions (see 4.5) to prepare
a series of standard solutions according to Table 2. The medium is 2 % nitric acid (see
4.4).
4.8 Mixed internal standard solution: 10 mg/L mixed standard solution of lutetium,
indium, bismuth, germanium, rhodium, and terbium. Prepare according to GB/T 602 or
use a certified standard solution.
4.9 Internal standard solution (on-line internal standard solution): Take 2.5 mL of the
mixed internal standard solution (see 4.8), adjust the volume to 50 mL with nitric acid
(see 4.4), to obtain a standard internal standard solution with a concentration of 500
μg/L.
4.10 Argon gas: purity ≥ 99.99 %.
4.11 Helium: purity ≥ 99.99 %.
5 Instruments
Unless otherwise stated, use general laboratory instruments in the analysis. One-mark
volumetric flasks shall comply with the provisions of GB/T 12806.
5.1 Inductively coupled plasma mass spectrometer (ICP-MS): equipped with a
hydrofluoric acid solution resistant atomization sample injection system. See Annex A
for working parameters of the instrument.
5.2 Microwave digestion instrument: see Annex B for working parameters.
5.3 Analytical balance: the scale value is 0.1 mg.
5.4 Pipette: the pipette range is 100 μL, 1000 μL, and 10 mL.
6 Sampling and sample preparation
6.1 Laboratory samples
Sampling and preparation shall be carried out in accordance with GB/T 10322.1.
Generally, the sample particle size is less than 100 μm. If the content of combined water
or easy oxides in the sample is high, the particle size shall be less than 160 μm.
For provisions regarding high combined water and easy oxides content, see GB/T
6730.1.
6.2 Pre-dried samples
Thoroughly mix the laboratory samples and take samples using the sample splitting
method. According to the provisions of GB/T 6730.1, dry the sample at a temperature
of 105 ℃ ± 2 ℃, and cool it to room temperature in a desiccator for later use.
7 Analysis steps
7.1 Number of determinations
According to Annex C, the same pre-dried sample shall be determined independently
at least twice, and the average value of the results shall be taken.
NOTE: “Independent” means that the results of the second and any subsequent determination are
not affected by the results of the previous determinations. In this analytical method, this condition
means that the same determined object is independently and repeatedly determined in a short period
of time by the same operator using the same equipment and the same test method in the same
laboratory, including using appropriate recalibration.
7.2 Sample mass
Weigh 0.10 g of pre-dried sample (see 6.2), accurate to 0.0001 g. The sample weighing
operation shall be carried out as quickly as possible to prevent the sample from
absorbing moisture again.
7.3 Blank test and verification test
7.3.1 Blank test
Except for not adding the sample to be determined, the blank test shall be carried out in
accordance with 7.4. All reagents shall be taken from the same reagent bottle. When
analyzing multiple samples, it can use a blank value.
7.3.2 Verification test
Along with the sample analysis, carry out the verification test for reference materials of
the same type.
7.4 Digestion of sample
ADD 7 mL of hydrochloric acid (see 4.1), 1 mL of hydrofluoric acid (see 4.2), and 2.5
mL of nitric acid (see 4.3) to the sample, SHAKE well, TIGHTEN the sealed digestion
tank, and PUT it into the microwave digestion instrument. Refer to the microwave
digestion working conditions in Annex B for microwave digestion. TAKE it out, COOL
to room temperature, OPEN the digestion tank, TRANSFER the digested solution
directly to a 100 mL plastic volumetric flask, RINSE the digestion tank and lid with
water 3 ~ 5 times, COMBINE the washing liquid into the solution, DILUTE with nitric
acid (see 4.4) to the mark, MIX well, and LET STAND for later test.
7.5 Quantitative determination
7.5.1 Plotting of calibration curve
Inter-laboratory precision is used to evaluate the consistency between the final results
reported by two laboratories. After the two laboratories report the results according to
the same steps specified in 8.2.2, calculate according to formula (2):
where:
μ12 - the average value of the final results;
μ1 - the final result reported by Laboratory 1;
μ2 - the final result reported by Laboratory 2.
If |μ1 - μ2| ≤ R, the final results of the two laboratories are consistent.
8.2.4 Correctness check
The correctness check uses a certified reference material (CRM) or a reference material
(RM) for verification. The final laboratory result is compared with the standard value
Ac of CRM or RM. There will be two possibilities.
a) |μc - Ac| ≤ C, in this case, there is no significant difference between the determined
value and the standard value.
b) |μc - Ac| > C, in this case, there is a significant difference between the determined
value and the standard value.
where:
μc - the determined value of CRM or RM;
Ac - the standard value of CRM or RM;
C - the value depends on the type of CRM / RM used.
The C value of the certified reference material (CRM) or reference material (RM)
determined by multiple laboratories is calculated according to formula (3):
where:
R - the inter-laboratory reproducibility limit;
r - the in-laboratory repeatability limit;
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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