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(Leather heavy metals (lead, cadmium, mercury, chromium) screening method energy dispersive X fluorescence spectrometry)
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Basic data
| Standard ID | SN/T 5231-2019 (SN/T5231-2019) |
| Description (Translated English) | (Leather heavy metals (lead, cadmium, mercury, chromium) screening method energy dispersive X fluorescence spectrometry) |
| Sector / Industry | Commodity Inspection Standard (Recommended) |
| Classification of Chinese Standard | W04 |
| Classification of International Standard | 59.080.01 |
| Word Count Estimation | 8,831 |
| Date of Issue | 2019 |
| Date of Implementation | 2020-07-01 |
| Issuing agency(ies) | General Administration of Customs |
SN/T 5231-2019: (Leather heavy metals (lead, cadmium, mercury, chromium) screening method energy dispersive X fluorescence spectrometry)
---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Leather-Screening of heavy metals (Pb, Cd, Hg, Cr)
-Energy dispersive X-ray fluorescence spectrometric method
The People's Republic of China Entry-Exit Inspection and Quarantine Industry Standards
Issued by the General Administration of Customs of the People's Republic of China
2019-12-27 release
2020-07-01 Implementation
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.
The main drafters of this standard. Jiang Xiaoliang, He Peng, Yu Wenjia, Yan Jianyong, Lan Lili, Li Xiaojing, Lin Zhenyu, Wang Bin, Zeng Ming.
Screening method for heavy metals in leather (lead, cadmium, mercury, chromium)
Energy Dispersive X Fluorescence Spectrometry
Warning. The personnel using this standard should have practical experience in formal laboratory work. This standard does not point out all possible safety issues
question. The user is responsible for taking appropriate safety and health measures and ensuring compliance with the conditions stipulated by relevant national laws and regulations.
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
6.1 Series standard preparation
Weigh a certain amount of blank leather sample (4.11), fully cut it to about 2 mm, and then use a high-speed crusher (5.3) to crush to about 0.1 mm.
Add 10000 mg/kg standard stock, then add a certain amount of tetrahydrofuran (4.6), stir evenly with a mixer (5.6), then use three rolls
The grinder (5.7) performs grinding and rolling, and then presses the tablet with the tablet press (5.4) to make a standard with a concentration range of 50 mg/kg ~ 1000 mg/kg
Standard substance (at least 5 concentrations).
6.2 Preparation of standard working curve
Select the appropriate measurement conditions and energy range according to the instrument and equipment and the measured heavy metals, enter the standard product information, and sequentially set the series of standards
The quasi-object is put into the instrument for testing, and the heavy metal standard working curve is prepared, with heavy metal content as the X axis and heavy metal test intensity as the Y axis. X
Refer to Appendix A for the test conditions of the fluorescence spectrometer.
6.3 Testing
The sample should be representative and meet the requirements of QB/T 2706.Generally, the sample does not need to be cut and sampled and pre-treated to keep the sample surface free
The quality can be directly determined. Place the sample in the test window of the instrument. The test conditions and energy range are consistent with the measurement standard. Three points are randomly selected
Test, read the heavy metal concentration in the sample against the standard working curve. If the sample is found to be non-uniform, the test point should be increased.
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
8.1 Lower limit of determination
The lower limit of this method is shown in Table 1
Note. The lower limit of determination of different instruments will be different, the lower limit of this method is for reference only
8.2 Precision
In the same laboratory, the same operator uses the same equipment, presses the same test method, and performs the same test on the same test pair within a short period of time.
Like tests conducted independently of each other, the absolute difference between the two independent test results obtained is not greater than the arithmetic mean of the two measured values
20%.
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 < 20 mg/kg. When the test result is higher than or
When it is equal to the lower limit of determination listed in Table 1 of 8.1, other suitable methods can be used to verify and confirm according to the limit requirements.
10 Test report
The test report should at least provide the following.
a) Sample source and description;
b) Standards used;
c) the test method used;
d) Test results and their presentation;
e) Any details that deviate from this standard;
f) Test date.
Appendix A
(Informative appendix)
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