SN/T 5231-2019Leather heavy metals (lead, cadmium, mercury, chromium) screening method energy dispersive X fluorescence spectrometry (English PDF)

Foreword

This standard was drafted in accordance with the rules given in GB/T 1.1-2009.

This standard was proposed and managed by the General Administration of Customs of the People's Republic of China.

Drafting organizations of this standard. Jiangmen Customs of the People's Republic of China, Huangpu Customs of the People's Republic of China, Changsha of the People's Republic of China Customs, Shanghai Customs of the People's Republic of China, Guangzhou Customs of the People's Republic of China, Fuzhou University.

1 Scope

This standard specifies the test method for heavy metals (lead, cadmium, mercury, chromium) in leather-energy dispersive X-ray fluorescence spectrometry (ie ED-XRF) law).

This standard applies to the quantitative screening of heavy metals (lead, cadmium, mercury, chromium) in leather.

2 Normative references

The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this article Pieces. For undated reference documents, the latest version (including all amendments) is applicable to this document.

GB/T 8170 Numerical rounding rules and the expression and determination of limit values QB/T 2706 Leather chemical, physical, mechanical and color fastness test sampling site

3 Principle

Under the set conditions, the energy dispersive X-ray fluorescence spectrometer is used to determine the content of heavy metals (lead, cadmium, mercury, chromium) in the sample.

Analyze the X-ray fluorescence intensity, and calculate the heavy metal content of the sample according to the quantitative relationship between the X-ray fluorescence intensity and the content of the element to be measured.

content.

4 Reagents and materials

Unless otherwise specified, all reagents used in the analysis are of analytical grade.

4.1 Lead nitrate.

4.2 Cadmium nitrate tetrahydrate.

4.3 Mercury nitrate.

4.4 Chromium nitrate.

4.5 Sodium carboxymethyl cellulose.

4.6 Tetrahydrofuran.

4.7 Lead (Pb) element standard stock (10000 mg/kg). Weigh 0.016 g of lead nitrate (4.1), place it in a ceramic mortar (5.5), and add 0.984 g Sodium carboxymethyl cellulose (4.5), quickly and fully grind uniformly.

4.8 Cadmium (Cd) element standard stock (10000 mg/kg). Weigh 0.027 g of cadmium nitrate tetrahydrate (4.2) in a ceramic mortar (5.5), add Add 0.953 g of sodium carboxymethyl cellulose (4.5), and grind quickly and thoroughly.

4.9 Mercury (Hg) element standard stock (10000 mg/kg). Weigh 0.016 g of mercury nitrate (4.3), place it in a ceramic mortar (5.5), and add 0.984 g Sodium carboxymethyl cellulose (4.5), quickly and fully grind evenly.

Note. Mercury nitrate is highly toxic, so care should be taken to protect it during storage and preparation.

4.10 Chromium (Cr) element standard stock (10000 mg/kg). Weigh 0.046 g of chromium nitrate (4.4), place it in a ceramic mortar (5.5), and add 0.954 g Sodium carboxymethyl cellulose (4.5), quickly and fully grind evenly.

4.11 Blank leather samples. no target elements such as lead, cadmium, mercury, and chromium.

5 Apparatus and equipment

5.1 X fluorescence spectrum analyzer (EDX type).

5.2 Electronic balance. accuracy of 0.1 mg.

5.3 High-speed pulverizer.

5.4 Tablet press. The pressure is not less than 20 tons, and the die diameter is 10-20 mm.

5.5 Ceramic mortar.

5.6 Blender.

5.7 Three-roll mill.

6 Analysis steps

7 Result calculation

Calculate the content of heavy metals in leather according to formula (1).

Where.

Ci - the content of heavy metal elements in the sample, in milligrams per kilogram (mg/kg);

Ii - Test intensity of heavy metal elements, in units per microampere per second (cps/µA);

b - Intercept of the standard working curve of heavy metal elements, in units per microampere per second (cps/µA);

a - The slope of the standard working curve of heavy metal elements, in units of units per second per milliampere/mg per kilogram [(cps/µA)/(mg/kg)];

Take the arithmetic average of the test results as the test result, and round the value to ten digits in accordance with GB/T 8170.

8 Low limit of determination and precision

9 Quantitative screening and evaluation

When the test result is lower than the lower limit of determination listed in 8.1 Table 1, the test result is expressed as Appendix A (Informative appendix)