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HJ 780-2015: Soil and sediment. Determination of inorganic element. Wavelength dispersive X-ray fluorescence spectrometry
HJ 780-2015
HJ
NATIONAL ENVIRONMENTAL PROTECTION
STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA
Soil and Sediment – Determination of Inorganic Element –
Wavelength Dispersive X-Ray Fluorescence Spectrometry
ISSUED ON: DECEMBER 14, 2015
IMPLEMENTED ON: FEBRUARY 01, 2016
Issued by: Ministry of Environmental Protection
Table of Contents
Foreword ... 4
1 Scope ... 5
2 Normative References ... 5
3 Principle of Method ... 5
4 Interference and Elimination ... 6
5 Reagents and Materials ... 6
6 Apparatus ... 6
7 Sample ... 7
8 Analysis Procedure ... 7
9 Calculation and Expression of Results ... 8
10 Precision and Accuracy ... 9
11 Quality Assurance and Quality Control ... 9
12 Precautions ... 10
Appendix A (Normative) Detection Limit and Determination Lower Limit of the
Method ... 11
Appendix B (Informative) Matrix Effect Correction, Spectral Line Overlapping
Interference ... 12
Appendix C (informative) Reference Conditions of Analytical Instrument ... 14
Appendix D (Informative) Calibration Curve Range of the Measuring Element ... 20
Appendix E (Informative) Summary Data on Method Precision and Accuracy ... 21
Soil and Sediment – Determination of Inorganic Element –
Wavelength Dispersive X-Ray Fluorescence Spectrometry
1 Scope
This Standard specifies the wavelength dispersive X-ray fluorescence spectrometry method for
the determination of 25 inorganic elements and 7 oxides in soil and sediment.
This Standard is application to the determination of 25 inorganic elements and 7 oxides in
soil and sediment; including Arsenic (As), Barium (Ba), Bromine (Br), Cerium (Ce), Chlorine
(Cl), Cobalt (Co), Chromium (Cr), Copper (Cu), Gallium (Ga), Hafnium (Hf), Lanthanum (La),
Manganese (Mn), Nickel (Ni), Phosphorus (P), Lead (Pb), Rubidium (Rb), Sulfur (S),
Scandium (Sc), Strontium (Sr), Thorium (Th), Titanium (Ti), Vanadium (V), Yttrium (Y), Zinc
(Zn), Zirconium (Zr), Silicon Dioxide (SiO2), Aluminum Oxide (Al2O3), Ferric Oxide (Fe2O3),
Potassium Oxide (K2O), Sodium Oxide (Na2O), Calcium Oxide (CaO), Magnesium Oxide
(MgO).
The detection limit of this method for 22 inorganic elements is 1.0mg/kg~50.0mg/kg; the lower
limit for determination is 3.0mg/kg~150mg/kg. The detection limit for 7 oxides is
0.05%~0.27%; the determination lower limit is 0.15%~0.81%. See Appendix A for details.
2 Normative References
The content of this Standard refers to the following documents or their clauses. For undated
references, their valid versions apply to this Standard.
GB 17378.3 The Specification for Marine Monitoring - Part 3: Sample Collection Storage
and Transportation
GB 17378.5 The Specification for Marine Monitoring - Part 5: Sediment Analysis
HJ/T 166 Technical Specification for Soil Environmental Monitoring
3 Principle of Method
After the soil or sediment sample is pressed by a liner or an aluminum ring (or plastic ring), the
atoms in the specimen are excited by appropriate high-energy radiation, and then the
characteristic X-rays of the atoms are emitted; and the intensity of it is directly proportional to
the mass fraction of the element in the specimen. The mass fraction of each element in the
specimen is quantitatively analyzed by measuring the intensity of characteristic X-rays.
4 Interference and Elimination
4.1 The X-ray fluorescence intensity value produced by the atoms of the element to be measured
in the specimen after being excited by radiation is related to the mass fraction of the element
and the mass absorption coefficient of the primary spectrum. The characteristic spectral line of
an element is photoelectrically absorbed by another element in the matrix, which shall produce
a matrix effect (that is, the inter-element absorption-enhancement effect). This matrix effect can
be eliminated after accurate calculation and processing by the basic parameter method, the
influence coefficient method or a combination of the two methods (i.e., the empirical coefficient
method) (see Appendix B).
4.2 The uniformity and surface characteristics of the specimen shall affect the measurement
intensity of the analytical line. If the particle size of the specimen is consistent with that of the
standard sample, then these effects can be minimized or even negligible.
4.3 Use the interference correction coefficient to correct the overlapping interference of spectral
lines (see Appendix B). Calculation method of overlapping interference correction coefficient:
through element scanning, analyze the interference line related to the analysis line of the
element to be measured; and determine the interference elements participating in the spectral
line overlapping correction. Use the method of directly measuring the interference line to
correct the X-ray intensity by the standard sample, and obtain the spectrum line overlapping
correction factor.
5 Reagents and Materials
5.1 Boric acid (H3BO3): analytically pure.
5.2 High-density low-pressure polyethylene powder: analytically pure.
5.3 Standard samples: soil, sediment, commercially available certified standard substances or
standard samples containing 25 inorganic elements and 7 oxides.
5.4 Plastic ring: inner diameter 34 mm.
5.5 Argon-methane gas: P10 gas, 90% argon + 10% methane.
6 Apparatus
6.1 X-ray fluorescence spectrometer: wavelength dispersion type, equipped with computer
control system, see Appendix C for targets and spectroscopic crystals.
6.2 Powder pressing machine: the pressure is 3.9×105N.
6.3 Analytical balance: precision 1 mg.
6.4 Sieve: non-metallic sieve with a hole diameter of 0.075 mm, and 200 mesh.
7 Sample
7.1 Collection, preservation and pretreatment of sample
The collection and preservation of soil samples shall be carried out in accordance with HJ/T
166; and the collection and preservation of sediment samples shall be carried out in accordance
with GB17378.3 and GB17378.5. Air-drying or oven-drying of the samples shall be carried out
in accordance with the relevant provisions of HJ/T 166 and GB17378.5. After the samples are
ground, pass through a 200-mesh sieve and dry at 105°C for later use.
7.2 Preparation of specimen
Use boric acid (5.1) or high-density low-pressure polyethylene powder (5.2) for putting at the
bottom and trimming, or use plastic ring (5.4) for trimming; and press about 5 g of the sieved
sample (7.1) on a pressing machine at a certain pressure to make it ≥ 7 mm thick slices.
Determine the pressure and retention time according to the press machine and the trimming
material.
8 Analysis Procedure
8.1 Establishing the measurement method
Refer to the instrument operating procedure to establish the measurement method. According
to the determined measurement elements, the measurement spectral lines are selected from the
database and corrected. Different models of instruments have different measurement conditions.
Refer to the database provided by the instrument manufacturer to select the best working
conditions, mainly including the high voltage and current of the X-ray tube, the analysis line of
the element, the spectroscopic crystal, the collimator, the detector, the pulse height distribution
(PHA), background correction. Appendix C gives the working conditions of some instrumental
analysis.
8.2 Calibration curve
Following the same operation procedure as the sample preparation (7.2), press at least 20
standard samples (5.3) elements with different mass fraction into thin slices. See Appendix D
for the mass fraction ranges of 25 inorg...