QC/T 941-2013Test method for mercury in automotive materials (English PDF)

3.1 Principle

Place a sample prepared in the sample chamber of X-ray fluorescence spectrometer; carry out X-ray analysis for the sample in accordance with the analysis mode selected.

Determine whether the mercury content (Hg) in the sample is acceptable in accordance with the screening limits of mercury element and whether further tests will be needed.

3.2 Reagents and materials

3.3 Instruments and equipment

3.3.5 Tablet press. working pressure not lower than 20 MPa

3.3.1 X-ray fluorescence spectrometer

3.3.2 Cutter

3.3.3 Liquid nitrogen low-temperature mill

3.3.4 Grinder. wolfram carbide (WC) abrasive tools

3.4 Sample preparation

3.4.1 Principles for sample preparation.

3.5.4 Calibration

Before a sample is tested each time, use the standard substance (3.2.3) to calibrate standard curves.

3.5.5 Sample testing

Place the sample prepared into the sample chamber; and carry out X-ray analysis for the sample in accordance with the selected mode, at least two times for each sample.

3.6 Result analysis

3.6.1 Result calculation

Calculate the content of mercury element in the sample in accordance with the selected analysis mode, using the intensity of the spectral lines of mercury element measured.

4 Cold Atomic Absorption Spectrometric Method, Atomic Fluorescence Spectrometric Method, Inductively Coupled Plasma Atomic Emission Spectrometric Method or Inductively Coupled Plasma Mass Spectrometric Method

4.1 Principle

Weigh an appropriate amount of sample; make a homogeneous sample solution after treatment by microwave digestion or wet reflux digestion.

4.2 Reagents and materials

Unless otherwise specified, only reagents confirmed to be of analytical grade and distilled water or deionized water or equivalent water shall be used in the analysis.

4.2.2 Hydrochloride acid. rho is 1.19 g/mg.

4.2.11 25 g/L potassium dichromate solution. weigh 2.5 g of potassium dichromate to dissolve in 100 mL of water.

4.2.13 1% sodium hydroxide-3% sodium borohydride. use water to dissolve 1.0 g of sodium hydroxide in a 1000 mL plastic volumetric flask; add 3.0 g of sodium borohydride; stir to dissolve; use water to dilute to scale; and use immediately after preparation.

4.2.14 0.05% sodium hydroxide-1% potassium borohydride. use water to dissolve 0.05 g of sodium hydroxide in a 100 mL plastic volumetric flask; add 1.0 g of potassium borohydride; stir to dissolve; use water to dilute to scale; and use immediately after preparation.

4.2.1 Nitric acid. rho is 1.40 g/mL

4.2.12 Nitric acid-potassium dichromate solution. weigh

0.5 g of potassium dichromate to dissolve in water; add 50 mL of nitric acid solution (4.2.1); transfer to a 1000 mL volumetric flask; use water to dilute to scale; and shake up.

4.3 Instruments and equipment

4.3.5 Inductively coupled plasma source mass spectrometer (ICP-MS)

4.3.4 Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES/OES)

4.3.1 Microwave digestion system

4.3.2 Cold Vapour atomic absorption spectrometer (CVAAS)

4.3.3 Atomic fluorescence spectrometer (AFS)

4.3.6 Liquid nitrogen low-temperature mill

4.4 Sample preparation

4.4.1 Sample pulverization

Make a sample into test pieces of not larger than 1 mm x 1 mm x 1 mm or direct come to the next step of work for the metallic materials or inorganic non-metallic materials in other materials; use a liquid nitrogen low-temperature mill (4.3.8) to continue to pulverize into power of grain size smaller than 0.5 mm for the polymer materials and electronic materials in other materials and come to the next step of work after mixing up.

4.4.2 Sample solution preparation

4.4.2.1 Preparation of sample solution for metallic materials.

4.5 Analytical procedure

4.5.1 Preparation of mercury standard solution.

Use (5 + 95) nitric acid solution (4.2.7) to dilute mercury standard stock solution (4.2.16)

[If a dissolved mercury oxide is used as the mercury stock solution, 0.5 mL of potassium dichromate (4.2.11) shall be added]; and prepare at least 5 concentrations of standard solution.

4.5.5 Sample determination

After establishing the calibration curve, test blank solution and sample solution. Look up the corresponding concentrations from the calibration curve based on the signal readings of each sample. Each sample shall be tested independently twice at least.

Take one sample at least in each batch of samples to conduct the test of adding standard recovery, the recovery rate between 90% and 110%. In the case of the cold atomic absorption spectrometric method or atomic fluorescence spectrometric method, mercury (Hg) shall be reduced to an atomic state with an appropriate method prior to analysis.

5.1 Principle

Weigh an appropriate amount of sample; place into an oxidation and decomposition furnace; use the heat and chemical action to decompose sample; absorb mercury in sample selectively before heating to release; use single-wavelength atomic absorption spectrophotometer to test the content of mercury in sample.

5.4 Sample preparation

Take 100 mg (accurate to 0.1 mg) of a solid sample for general polymers and organic coatings to conduct tests, 500 mg at most. In the case of a liquid sample, take 100 µL (accurate to 1 µL) to conduct tests, 500 µL at most.

5.5 Analytical procedure

5.6 Result calculation

The content of mercury in a solid sample is calculated in accordance with Formula (2).

The content of mercury in a liquid sample is calculated in accordance with Formula (3). In the formula.