GB/T 28021-2011Adornment - Determination of baneful elements - Method of spectrometry (English PDF)

6.1 Sample preparation

6.2 Digestion of sample

6.2.1 Conventional acid digestion method

This method is applicable to samples specified in 6.1.1.

Weigh 0.3g~0.5g of samples for two portions, accurate to 0.1 mg; place them in the beaker or conical flask.

6.2.2 Pressure tank digestion method

This method is applicable to samples specified in 6.1.2.

Weigh 0.3g~0.5g of samples for two portions, accurate to 0.1 mg; place them in pressure tank (5.3); add 8 ml of nitric acid (4.1) and 2mL of hydrogen peroxide (4.7); as for materials such as glass and ceramics with many silicon, re-add 3 ml of hydrofluoric acid (4.8); cover it with a watch glass; tighten up; place it in an oven (5.2); heat for 4h at 180°C ±5°C.

6.2.3 Other digestion methods

After being verified and feasible other digestion methods such as microwave digestion, acid wet digestion, ashing method may be selected to process the samples specified in 6.1.2; and adopt the samples that fail to completely digest by method specified in 6.2.1.

6.3 Determination

6.3.1 AAS method

6.3.2.2 Preliminary test

Confirm the approximate content of each impurity elements in sample solution.

The concentration of to-be-tested element in calibration solutions shall not be less than the actual concentration of element in sample solution.

6.3.2.3 Accurate determination

According to the test result of 6.3.2.2, respectively add the standard stock solutions (4.9) of the tested elements into 100 ml volumetric flasks; dilute to the scale with aqua regia (4.6); then shake well and prepare the high/low standard calibration solutions.

The concentration interval between the tested elements in high/low standard solutions. cadmium not greater than 5 mg/L, other elements not greater than 20 mg/L.

Determine the sample solution (6.2) and calibration solution with plasma spectrometer.

Use the aqua regia (4.6) as the "zero point" calibration solution.

6.4 Expression of results

The content of arsenic, lead, mercury and cadmium in samples is counted by mass fraction w, the value is expressed by mg/kg, and is calculated according to Formula

7.1 Preparation of extracting solution

Weigh the to-be-tested sample with an analytical balance (5.4), accurate to 0.1 mg; place it in an appropriate covered container (5.6); add sufficient hydrochloric acid solution (4.4) with a temperature of 37°C±2°C; make sure that the sample is exactly immersed into the solution. Cover the container; place it in an oven (5.2) which can control the temperature for 2h at 37°C±2°C.

7.2 Determination

Determine the concentration of stibium, barium, selenium, arsenic, lead, mercury, cadmium or chromium extracting solution (7.1) with analytical spectrometer (5.1) and according to the method specified in 6.3, that is to say, the hydrochloric acid (4.4) is as zero point correction solution and fix-volume solution.

7.3 Expression of results

7.3.1 Calculation of baneful elements dissolution quantity

The dissolution quantity of baneful elements in sample is counted by mass fraction w, the value is expressed by mg/kg and is calculated according to Formula (2).

7.3.2 Interpretation of results

Because of precision of test method specified in this Standard, when considering the test results between laboratories, a corrected analytical result is needed. The analysis result calculated in 7.3.1 shall deduct the analysis correction value in Table 1, so as to obtain the analysis result after correcting.