GB/T 46747-2025Rapid determination of heavy metals in furniture coatings - X-ray fluorescence spectrometry (English PDF)

1 Scope

GB/T 46747-2025 is the Chinese national standard covering screening furniture finishes for lead, cadmium, chromium and mercury with a handheld or benchtop XRF - the calibration and the reference materials, the effect of coating thickness on the reading, and the threshold at which a laboratory confirmation is required. It is a screening method: it says which pieces need the destructive test, not which pass. First edition, in force from 1 May 2026. Issued on 31 October 2025, it has been in force since 1 May 2026.

This document describes the X-ray fluorescence spectrometry for the rapid determination of eight heavy metals-lead, cadmium, chromium, barium, mercury, arsenic, selenium, and antimony-in furniture coatings. This document is applicable to the rapid determination of lead, cadmium, chromium, barium, mercury, arsenic, selenium, and antimony in the surface paint coatings of wooden and metal furniture; it is also applicable to the screening of the migration levels of these eight elements within such coatings. NOTE. If the elemental content exceeds the prescribed migration limit, chemical analysis methods shall be employed to further verify the actual migration level.

2 Normative References

The contents of the following documents constitute indispensable clauses of this document through normative references in the text. In terms of references with a specified date, only versions with a specified date are applicable to this document. In terms of references without a specified date, the latest version (including all the modifications) is applicable to this document.

GB/T 16597 Analytical methods of metallurgical products - General rule for X-ray fluorescence spectrometric methods

GB/T 37361 Determination of the film thickness - Ultrasonic thickness gauge method

JB/T 12962.1 Energy dispersive X-ray fluorescence spectrometer - Part

3 Terms and Definitions

The following terms and definitions are applicable to this document.

3.1 Fundamental Parameter Method A theoretical calculation method for determining the elemental content of a sample. It involves utilizing mathematical models based on a fundamental parameter library to theoretically calculate the spectral distribution of primary incident X-rays, the interactions between X-rays and matter (including mass absorption coefficients, fluorescence yields, spectral line fractions, absorption edge ratios, scattering, etc.), and instrumental optical path influence factors. This process generates a calculated spectrum, which is then iteratively refined against the spectrum acquired by the detector-using an iterative algorithm-until the required level of precision is achieved.

4 Principle

Primary X-rays generated by an X-ray tube are filtered or monochromated before irradiating the sample surface. This excitation causes inner-shell electrons of the elements under analysis to undergo energy-level transitions, thereby emitting characteristic X-ray fluorescence specific to each element. An energy-dispersive detector resolves the characteristic X-ray fluorescence from different elements and measures their intensities; after theoretical calculation using the fundamental parameter method, these intensities are found to be directly proportional to the mass fractions of the elements within the sample. Calibration curves are established using either standard samples/reference materials or calibration samples prepared via the standard addition method, thereby enabling the determination of the mass fractions of the target elements within the sample.

5 Reagents and Materials

5.1 Mixed standard solution of lead, cadmium, chromium, mercury, arsenic, selenium, and antimony. Use elemental standard stock solutions that have been nationally certified and issued a standard sample/reference material certificate. The mass concentration shall be 1 000 mg/L or higher, and the matrix shall be water-based, a 5% (or lower) hydrochloric acid (or nitric acid) matrix, or an organic matrix.

5.2 Barium standard solution. Use an elemental standard stock solution that has been nationally certified and issued a standard sample/reference material certificate. The mass concentration shall be 10 000 mg/L, and the matrix shall be a 5% (or lower) nitric acid matrix or an organic matrix.

5.3 Blank paint. Water-based wood paint, acrylic-based wood paint, or other paints commonly used for wooden furniture, wherein the content of each of the eight elements under analysis is less than

0.5 mg/kg.

5.4 Wooden materials or metal substrates. Preferably use wooden materials or metal substrates commonly used in furniture manufacturing.

5.5 Glass plate or polytetrafluoroethylene (PTFE) plate. The surface must be flat, and the material must be resistant to solvent corrosion.

6 Instruments and Equipment

6.1 X-ray fluorescence spectrometer. A benchtop or handheld energy-dispersive X-ray fluorescence spectrometer complying with the provisions of JB/T 12962.1 or GB/T 16597.The detector resolution shall be less than 135eV@Mn.Ka; the accompanying software shall feature quantitative analysis capabilities based on the fundamental parameter method and allow for the customization of multi-layer sample structures.

6.2 Manual coater. An adjustable doctor blade-type or fixed-gap-type coater with a flat surface. The material shall be resistant to solvent corrosion, non-reactive with paint, and designed to prevent contamination.

6.3 Cutter. An electric saw or other tool suitable for cutting wooden materials and metallic materials.

6.4 Ultrasonic thickness gauge. An instrument with an accuracy of no less than 1 µm and a maximum measurement range of no less than 500 µm.

7 Preparation of Test Specimens

When using a benchtop X-ray fluorescence spectrometer, use the cutter (6.3) to cut the furniture sample into dimensions that match the sample aperture of the instrument. When using a handheld X-ray fluorescence spectrometer, cutting of the furniture sample is not required; tests may be performed directly on a flat surface of the furniture.