QC/T 943-2013Test method for lead and cadmium in automotive materials (English PDF)

3.1 Principle

Place the prepared samples in X-ray fluorescence spectrophotometer sample chamber.

According to the selected analytical model, conduct X-ray fluorescence spectroscopy analysis for the lead and cadmium content in the samples. According to the screening values, judge if the lead and cadmium content is qualified in the samples, and if it is required for further accurate determination.

3.2 Reagents and materials

3.3 Instruments and equipment

3.3.4 Tableting machine. Working pressure is not less than 20Mpa.

3.3.1 X-ray fluorescence spectrophotometer

3.3.2 Cutting machine

3.3.3 Crushing equipment. Pulverizer, grinder

3.4 Sample preparation

3.4.1 Principle of sample preparation.

3.4.2 Sample preparation method

3.4.2.1 Solid samples. Homogeneous samples may be determined directly by the X-ray fluorescence spectrophotometer. The sample size must meet the requirements of X-ray fluorescence spectrophotometer. In case of the sample is too big, it shall be processed into a smaller size of ±10mm - ± 40mm, and with a smooth surface.

3.4.2.2 Fluid sample. PIPETTE a certain volume of liquid sample into the special plastic cup. USE the polyester film of 6mm in thickness to support the bottom of sample cup.

COVER the cup with an aperture plastic cap. The thickness of the sample is not less than 15mm.

3.5 Analytical steps

3.5.1 Instrument preparation

TURN on the instrument in accordance with the operational specifications of the instrument. PREHEAT the instrument to be stable.

3.5.2 Analyze the spectral line

For X-ray fluorescence spectrometry, the analysis spectral line is recommended to select lead; Cadmium.

3.5.3 Drawing of working curve

SELECT different content's lead and cadmium standard substances that match the tested sample matrix and have no less than 5 points. MEASURE the fluorescence intensity of lead and cadmium in the standard substances in accordance with the measurement conditions of X-ray fluorescence spectrometer. DRAW the working curve in accordance with the given standard values by the standard substances and the measured fluorescence intensity values by the spectrometer.

3.6 Analysis of result

3.6.1 Calculation of result

According to the selected analysis mode, CALCULATE the lead and cadmium content in the sample, based on the measured spectral line intensity of elements lead and cadmium.

4 Measure the lead and cadmium in the materials of steel, copper and copper alloy, aluminum and aluminum alloy - photoelectric direct reading spectrometry

4.2 Principle

After the processed sample is excited by light source, the radiated light enters into the beam splitting system through the entrance slit to disperse into spectrum. CONDUCT the photovoltaic conversion for the selected spectral lines by the photo-translating system and measuring system. And measure the spectral line intensity. MEASURE the mass fraction of elements lead and cadmium, according to the working curve made by corresponding standard substances (standard samples).

4.3 Auxiliary materials

4.3.1 Standard substance (standard sample). It shall be a national or recognized authoritative standard substance (standard sample). In principle, the standard substance (standard sample) shall be basically consistent with the chemical composition and metallurgical casting process of the analytical sample.

4.3.2 Control sample. The standard sample that has the exact constant value and has a similar matrix and organization structure with the sample to be tested.

4.4 Instruments and equipment

4.4.2 Sample processing equipment. Grinding machine (sandpaper millstone, abrasive band grinding machine), lathe or milling machine.

4.4.1 Photoelectric direct reading spectrometer

4.5 Sample preparation

Sample shall be prepared according to the requirements of GB/T 20066. The surface of the taken sample shall ensure that it can excite 2 points without overlapping. And it can completely cover the excitation hole, so as to ensure that the excitation chamber does not leak gas.

4.6 Analytical steps

4.6.1 TURN on the instrument in accordance with the requirements of instrument specifications. PREHEAT the instrument to be stable.

4.6.2 Before analysis, firstly USE a sample for continuous excitation and good reproducibility. CONFIRM the instrument is in the best working condition.

4.6.3 According to the material type of sample, SELECT the corresponding appropriate standard substances (standard samples).

4.6.4 According to the type of sample and alloy designation, SELECT the analytical procedure.

4.6.5 Analysis of drift correction of curve. According to the type of sample to be tested, SELECT the control sample. The control sample is continuously excited and has good reproducibility. STORE the mean value, so as to confirm whether the analytical curve is drifted.

4.6.6 Sample analysis

The sample shall be excited to measure at least twice. The mean value shall be used as analysis results when the data is stable. The content is expressed by mass fraction (%).

Rounding off value is in accordance with GB / T 8170.

4.7 Precision

4.7.1 Repeatability

For the measured values of 11 independent test results obtained under repeatability conditions, within the given measured range as follows, their relative standard deviation shall not exceed the provisions of Table 3.

5 Atomic absorption spectrometry, inductive coupling plasma atomic emission spectroscopy or inductively coupled plasma mass spectrometry - measure lead and cadmium

5.1 Principle

WEIGH appropriate amount of sample. USE dissolved acid to completely digest the sample. PREPARE homogeneous solution. USE atomic absorption spectrometry, inductive coupling plasma atomic emission spectroscopy, or inductively coupled plasma mass spectrometry to measure lead and cadmium concentration in the solution.

5.2 Reagents and materials

Unless otherwise specified, in analysis, only USE recognized analytical pure reagent and distilled water or deionized water or water with equivalent purity.

5.3 Instruments and equipment

5.4 Sample preparation

5.4.1 Metal material

The sample is processed to debris with a thickness not more than 1mm.

5.5 Analytical steps

5.5.1 Sample

WEIGH 0.10g -1.00g of specimen, accurate to 0.0001g.

5.5.2 Determination number of times

PERFORM twice independent determination. TAKE the average values.

5.5.3 Blank test

MAKE a blank test along with the specimen.

5.5.4 Determination

5.5.4.1 Preparing solution of metal material. PLACE the sample (5.5.1) in 250mL beaker.

ADD appropriate amount of dissolved acid to heat to dissolve. After the sample to be tested is completely dissolved, REMOVE it into 100mL volumetric flask. DILUTE to the scale with water and mix evenly.

5.5.4.2 Preparation of polymer solution. PLACE the specimen (5.5.1) into microwave digestion tank. Respectively ADD 5mL of concentrated nitric acid, 1.5mL of tetrafluoro boric acid solution and 1.5mL of hydrogen peroxide. For samples containing more siliceous, it is required to add 1mL of tetrafluoro borate solution. If the sample contains a large number of easily oxidized organic ingredients, it cannot add hydrogen peroxide. CLOSE the digestion tank.

5.5.4.4 Preparation of rubber solution.

5.5.4.3 Preparation of coating solution

5.5.4.5 Measurement of specimen solution. MEASURE the absorbency and intensity

values of the lead and cadmium in the blank test solution along with the specimen and the specimen solution WITH the atomic absorption spectrometer, inductive coupling plasma atomic emission spectrometer, and inductively coupled plasma mass spectrometry. And CHECK out the content of the lead and cadmium from the working curve.

5.5.5 Drawing of working curve

5.5.5.1 Preparation of standard solution working curve. According to the content of lead and cadmium, PREPARE the standard solutions not less than 5 points and with different concentration of lead and cadmium. If the sample matrix has interference on the measured elements, it can use matrix matching method to eliminate the interference. DILUTE with water to the scale. SHAKE evenly.

5.5.5.2 Preparation of working curve of standard substance. According to the material of the sample to be tested, CHOOSE the standard substances not less than 5 points and with different content of lead and cadmium. In accordance with the preparation method of analysis specimen, PREPARE standard substance solutions. DILUTE to the scale with water and mix evenly.

5.5.5.3 Measurement. ARRANGE the solutions of the standard solution working curve and the solutions of standard substance working curve, based on the sequence from low concentration to high concentration. MEASURE the absorbency or intensity value of the lead and cadmium WITH the atomic absorption spectrometer, inductive coupling plasma atomic emission spectrometer, and inductive coupling plasma mass spectrometer. TAKE mass of lead and cadmium as the abscissa; and absorbance and intensity value as the ordinate. DRAW the working curve.

5.6 Result calculation

According to Equation (1), CALULATE the mass fraction (%) of the lead and cadmium. The calculated result is rounded in accordance with GB/T 8170.

5.7 Precision

Under the repeatability conditions, the absolute difference value between the 2 independent determination results shall not exceed 10% of the arithmetic mean value.