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This standard was drafted in accordance with the rules given in GB/T 1.1-2009 Directives for Standardization—Part 1: Structure and Drafting of Standards.
This standard includes five methods.
Method I: X-ray fluorescence spectrometry, developed by reference to GB/Z 21277-2007 Rapid Screening of Lead Mercury Chromium Cadmium and Bromine of Regulated Substances in Electrical and Electronic Equipment—X-Ray Fluorescence Spectrometry.
Method II: qualitative test on hexavalent chromium in anti-corrosive metal coating, developed by reference to IEC 62321:2008 Ed.1.0 Electrotechnical Products—Determination of Levels of Six Regulated Substances (Lead, Mercury, Cadmium, Hexavalent Chromium, Polybrominated Biphenyls, Polybrominated Diphenyl Ethers), Annex B.
Method III: determination of hexavalent chromium content in anti-corrosive metal coating, developed by reference to ISO 3613:2000 Chromate Conversion Coatings on Zinc, Cadmium, Aluminium—Zinc Alloys and Zinc-Aluminium Alloys—Test Methods.
Method IV: determination of hexavalent chromium content in polymer material and electronic material, developed by reference to IEC 62321:2008 Ed.1.0 Electrotechnical Products—Determination of Levels of Six Regulated Substances (Lead, Mercury, Cadmium, Hexavalent Chromium, Polybrominated Biphenyls, Polybrominated Diphenyl Ethers), Annex C; it is nonequivalent to IEC 62321:2008 Ed.1.0. This method is consistent with Annex C of the international standard in technical content, but different from it greatly in standard framework.
Method V: determination of hexavalent chromium content in leather, developed by reference to EN ISO 17075:2007 Leather—Chemical Tests—Determination of Chromium (6) Content; it is nonequivalent to EN ISO 17075:2007. This method is consistent with the international standard in technical content, but different from it greatly in standard framework. The sample preparation clauses are refined according to the contents of normative references stated in the international standard, i.e., the determination of volatile content in sample is refined into Annex C (Normative) in this standard.
In this standard, Annex A is informative, while Annex B, Annex C and Annex D are normative.
This standard was proposed by and is under the jurisdiction of the National Technical Committee on Automobiles of Standardization Administration of China (SAC/TC 114).
Introduction
The metallic chromium is non-toxic and its chemical property is stable. However, chromic compound, especially hexavalent chromium, is toxic. Hexavalent chromium, a toxic substance with dispatching hazard, may induce cancer. Policy on Automobile Product Recycling Technology issued in 2006 restricts the use of heavy metals, including hexavalent chromium, in automobile products. The national standard GB/T 30512-2014 Requirements for Prohibited Substances on Automobiles specifies the limit of hexavalent chromium content in automobile parts and the materials.
This standard is applicable to determination of hexavalent chromium content in automobile parts and the materials, so as to assess the compliance with those specified in Requirements for Prohibited Substances on Automobiles. This standard serves as the basis for inspecting the automobile quality and controlling the prohibited substances in the automobile parts and materials since the date of issuance and implementation.
For the purpose of this standard, the hexavalent chromium is extracted from the automobile parts and materials using different extraction methods, i.e., different extraction procedures (e.g., different extracts, pH values, and extraction periods) are adopted for different kinds of automobile parts and materials to extract the soluble hexavalent chromium from the samples. The result obtained from the method specified herein depends on the extraction conditions strictly; therefore, it is meaningless to compare with the result obtained from other extraction procedure.
Attentions shall be paid to handle and store the samples possibly containing hexavalent chromium and the reagents to be used in test with care. The solution or waste containing hexavalent chromium shall be handled in a correct way. For example, the hexavalent chromium may be reduced to trivalent chromium by ascorbic acid or other reductant. Therefore, the personnel using this standard shall have practical experience of working in regular laboratory. This standard does not point out all possible safety problems; the user is obliged to take proper safety and health measures, and to guarantee compliance with the relevant national laws and regulations.
Test Methods of Hexavalent Chromium in Automobiles Materials
1 Scope
This standard specifies the methods for determining the hexavalent chromium content in automobile parts and materials. Among them,
"X-ray fluorescence spectrometry" is applicable for screening and fast determining the hexavalent chromium content in automobile materials using X-ray fluorescence spectrometry.
"Qualitative test on hexavalent chromium in anti-corrosive metal coating" is applicable for determining the existence of hexavalent chromium in anti-corrosive coating of automobile using spot method and boiling extraction method. "Determination of hexavalent chromium content in anti-corrosive metal coating" is applicable for determining the hexavalent chromium content in anti-corrosive coating using boiling extraction method and colorimetry. The two methods are applicable to coating without additional covering layers (such as oil film, water-based or solvent-based polymer film or waxy film).
"Determination of hexavalent chromium content in polymer material and electronic material" is applicable for determining the hexavalent chromium content in polymer materials and electronic materials using alkali liquor extraction method and colorimetry, but not applicable to PE and EVAC materials. The hexavalent chromium content in other automobile materials, such as glass, ceramics, fabric, and paint coating, is determined by reference to this method.
"Determination of hexavalent chromium content in leather" is applicable for determining the hexavalent chromium content in leather using phosphate solution extraction method and colorimetry.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 1839 Steel Product Zinc Coating Mass Testing Method (GB/T 1839-2008, ISO 1460:1992, MOD)
GB/T 8170 Rules of Rounding Off for Numerical Values & Expression and Judgment of Limiting Values
GB/T 20017 Metallic and Other Non-organic Coatings—Determination of Mass per Unit Area—Review of Gravimetric and Chemical Analysis Methods (GB/T 20017-2005, ISO 10111:2000, IDT)
GB/T 30512-2014 Requirements for Prohibited Substances on Automobiles
GB/Z 21277-2007 Rapid Screening of Lead, Mercury, Chromium, Cadmium and Bromine of Regulated Substances in Electrical and Electronic Equipment—X-ray Fluorescence Spectrometry
QB/T 2262-1996 Terms for Leather Industry
QB/T 2706 Leather—Chemical, Physical and Mechanical and Fastness Tests—Sampling Location (QB/T 2706-2005, ISO 2418:2002, MOD)
IEC 62321:2008 Ed.1.0 Electrotechnical Products—Determination of Levels of Six Regulated Substances (Lead, Mercury, Cadmium, Hexavalent Chromium, Polybrominated Biphenyls, Polybrominated Diphenyl Ethers)
ISO 3613:2000 Chromate Conversion Coatings on Zinc, Cadmium, Aluminium—Zinc Alloys and Zinc-Aluminium Alloys—Test Methods
EN ISO 17075:2007 Leather—Chemical Tests—Determination of Chromium(6) Content
3 X-Ray Fluorescence Spectrometry
3.1 Principle
Put the prepared sample into the sample room of X-ray fluorescence spectrometry; carry out X-ray fluorescence spectrometric analysis on the chromium content in the sample according to the analysis mode selected, and judge whether the chromium content conforms to the screening limit, and whether accurate determination is necessary.
Note: the result obtained by X-ray fluorescence spectrometric analysis is the total chromium in the sample, rather than the hexavalent chromium.
3.2 Reagents and materials
3.2.1 Boric acid: guaranteed reagent, baking 1h at 105℃ and storing in the dryer.
3.2.2 Anhydrous lithium tetraborate: guaranteed reagent, baking 4h at 700℃ and storing in the dryer.
3.2.3 Liquid nitrogen: industrial grade.
3.2.4 Standard material containing chromium.
3.3 Apparatus
3.3.1 X-ray fluorescence spectrometer.
3.3.2 Cutter.
3.3.3 Liquid nitrogen low-temperature pulverizer.
3.3.4 Grinder: grinding apparatus with wolfram carbide (WC).
3.3.5 Tablet press: the working pressure ≥20MPa.
3.3.6 Fusion machine: working temperature ≥1150℃.
3.4 Sample preparation
3.4.1 Sample preparation principal.
3.4.1.1 The sample subject to analysis must cover the measuring window of spectrometer.
3.4.1.2 The sample's exposure side shall be able to represent the entire sample.
3.4.1.3 Attention shall be paid to prevent pollution during sample preparation.
3.4.2 Sample preparation method.
3.4.2.1 Solid samples. Direct analysis may be conducted on the homogeneous samples with the smooth surface and size suitable for the X-ray fluorescence spectrometer. Small samples may be gathered together for analysis. The thin samples may be stacked to reach the sufficient thickness (at least 5mm). Special attention shall be paid to the consistency of sample thickness and homogeneity of composition. During analysis, spread the samples in a flat and smooth way; lining material may be added to serve as the support; lining material with low background is recommended.
Irregularly-shaped or oversized samples, such as blocks, plates, shall be processed to the proper size with cutter, grinder, etc. Small samples (such as plastic particles) shall be pressed by tablet press to be analytical samples after undergoing liquid nitrogen refrigeration and mechanical grinding.
The fragile samples, such as glass and ceramics, shall be pulverized into small blocks, and then grinded to powder less than 200-mesh (0.074mm). Mix the powder uniformly. Put the boric acid (3.2.1) at the bottom to prepare the sample with tablet press, and the bottom thickness shall not be less than 1mm; or use anhydrous lithium tetraborate (3.2.2) to prepare analytical sample of glass melting piece.
As for the heterogeneous sample composed of heterogeneous materials and with further mechanical separation not necessary or difficult, cut to break the sample and subject it to liquid nitrogen refrigeration. Use the grinder to grind the broken sample into powder with particle size not more than 1mm. Mix the powder uniformly. Put the boric acid (3.2.1) at the bottom to prepare the sample with tablet press, and the thickness shall not be less than 1mm; or use anhydrous lithium tetraborate (3.2.2) to prepare analytical sample of glass melting piece.
3.4.2.2 Liquid sample. Transfer a certain volume of liquid sample into the liquid-dedicated sample cup (the sample thickness is at least 15mm); the cup is supported by 6mm-thick polyester film at bottom, and covered by perforated cap.
3.5 Analytical procedures
3.5.1 Preparation of apparatus.
Activate the apparatus according to the operation procedures, and preheat the apparatus until it gets stable.
3.5.2 Analytical line.
Kα analytical line is recommended for analyzing chromium with X-ray fluorescence spectrometry.
3.5.3 Plotting of working curve
Select the standard material which basically matches to the to-be-tested sample; determine the fluorescence intensity of chromium in the standard material under the measuring conditions of X-ray fluorescence spectrometer; plot the working curve based on the standard value given for the standard material and the intensity measured by the spectrometer.
3.5.4 Calibration.
Before testing the sample every time, calibrate the working curve using the chromium-containing standard material (3.2.4).
3.5.5 Sample testing.
Put the prepared sample into the sample room, and analyze the sample according to the selected mode. Each sample shall be analyzed twice at least.
3.6 Result analysis
3.6.1 Result calculation.
Calculate the chromium content in the sample using the obtained spectral line intensity of chromium, according to the selected analysis mode.
3.6.2 Screening of hexavalent chromium.
Set the screening limits (Table 1) of chromium in automobile materials according to Requirements for Prohibited Substances on Automobiles which specifies that the limit of hexavalent chromium (calculated in total chromium) is mass fraction 0.1% (1000mg/kg); screen the chromium in automobile material according to the screening limits. Two results are obtained:
Pass (P)——it is conforming if all the analysis results are below the lower limit;
Unknown (X)——it is unknown if the analysis results exceed the lower limit, and the hexavalent chromium shall be determined.
Table 1 Screening Limits of Chromium Content in Automobile Materials mg/kg
Sample category Polymer Other materials
Screening limits P≤700-3S
Foreword i
Introduction ii
1 Scope
2 Normative References
3 X-Ray Fluorescence Spectrometry
4 Qualitative Test on Hexavalent Chromium in Anti-corrosive Metal Coating
5 Determination of Hexavalent Chromium Content in Anti-corrosive Metal Coating
6 Determination of Hexavalent Chromium Content in Polymer Material and Electronic Material
7 Determination of Hexavalent Chromium Content in Leather
8 Test Report
Annex A (Informative) Calculation Method of Fastener Coating Surface Area
Annex B (Normative) Determination of Recovery Rate and Detection Limit by Determination of Hexavalent Chromium Content in Polymer Material and Electronic Material
Annex C (Normative) Determination of Volatile Content in Leather
Annex D (Normative) Determination of Recovery Rate by Determination of Hexavalent Chromium Content in Leather
汽车材料中六价铬的检测方法
1 范围
本标准规定了汽车零部件及材料中六价铬含量的检测应运。其中：
“X射线荧光光谱法”适用于采用X射线荧光光谱法筛选和快速判定汽车材料中六价铬的含量。
“金属防腐镀层中六价铬定性试验”适用于采用点滴试验法和沸水萃取法定性确定汽车车防腐镀层中六价铬的存在。“金属防腐镀层中六价铬含量测定”适用于采用沸水萃取、比色法定量测定防腐镀层中六价铬的含量。“金属防腐镀层中六价铬定性试验”和“金属防腐镀层中六价铬含量测定”适用于无附加覆盖层（例如：油膜、水基或溶剂型聚合物膜或蜡膜）的镀层。
“聚合物材料和电子材料中六价铬含量测定”适用于采用碱液萃取、比色法测定汽车聚合物材料和汽车电子材料中六价铬的含量，不适用于聚乙烯（PE）和乙稀-乙酸乙烯酯共聚物（EVAC）材料。其他汽车材料，如玻璃、陶瓷、织物和油漆涂层中的六价铬含量参照本方法测定。
“皮革材料中六价铬含量测定”适用于采用磷酸盐液萃取、比色法测定汽车皮革材料中六价铬的含量。
2 规范性引用文件
下列文件对于本文件的应用是必不可少的。凡是注日期的引用文件，仅注日期的版本适用于本文件。凡是不注日期的引用文件，其最新版本（包括所有的修改单）适用于本文件。
GB/T 1839 钢产品镀锌层质量试验方法（GB/T 1839-2008，ISO 1460：1992，MOD）
GB/T 8170 数值修约规则与极限数值的表示和判定
GB/T 20017 金属和其他无机覆盖层 单位面积质量的测定 重量法和化学分析法评述（GB/T 20017-2005，ISO 10111：2000，IDT）
GB/T 30512-2014 汽车禁用物质要求
GB/T 21277-2007 电子电气产品中限用物质铅、汞、铬、镉和溴的快速筛选 X射线荧光光谱法
QB/T 2262-1996 皮革工业术语
QB/T 2706 皮革 化学、物理、机械和色牢度试验 取样部位（QB/T 2706-2005，ISO 2418：2002，MOD）
IEC 62321：2008 Ed.1.0 电子电气产品 六种限制物质（铅、汞、镉、六价铬、多溴联苯和多溴联苯醚）的规定
ISO 3613：2000 锌、镉、铝—锌合金及锌—铝合金表面铬酸盐的转化镀层—测试方法
EN ISO 17075：2007 皮料铬（六价铬）含量测试
3 X射线荧光光谱法
3.1 原理
将制备好的样品置于X射线荧光光谱仪样品室内，按所选定的分析模式对样品中的铬含量进行X射线荧光光谱分析，并根据筛选限值判断样品中铬含量是否合格，以及是否需要进行精确测定。
注：X射线荧光光谱分析所得结果是样品所含的总铬而非六价铬。
3.2 试剂和材料
3.2.1 硼酸：优级纯，105℃烘1h，储存于干燥内。
3.2.2 无水四硼酸锂：优级纯，700℃灼烧4h，储存于干燥器内。
3.2.3 液氮：工业级。
3.2.4 含铬元素的标准物质。
3.3 仪器和设备
3.3.1 X射线荧光光谱仪。
3.3.2 切割机。
3.3.3 液氮低温粉碎机。
3.3.4 研磨机：带碳化钨（WC）磨具。
3.3.5 压片机：工作压力不小于20MPa。
3.3.6 熔样机：工作温度不低于1150℃。
3.4 样品制备
3.4.1 样品制备原则。
3.4.1.1 用于分析的样品必须覆盖光谱仪的测量窗口。
3.4.1.2 样品的照射面应能代表样品整体。
3.4.1.3 样品制备过程中应注意防止污染。
3.4.2 样品制备方法。
3.4.2.1 固体样品。表面平整、大小适合X射线荧光光谱仪要求的均质样品，直接分析。小样品可汇在一起进行分析。薄样品，可将其叠在一起达到足够厚（厚度至少5mm），需特别注意样品厚度的一致性及组成的均匀性。分析时为使样品平整铺开，可加内衬材料作为支撑物，应尽量选用背景低的内衬材料。
各种块、板等不定形的样品以及尺寸过大的样品，可用切割机、研磨机等将其加工至合适尺寸。小样品（如塑料颗粒等）通过液氮冷冻、机械粉碎再经压片机压片制成分析样品。
玻璃、陶瓷等易碎样品先粉碎成小块，再研磨成小于200目（0.074mm）的粉末，混匀，用硼酸（3.2.1）衬底压片制样，厚底不小于1mm，或用无水四硼酸锂（3.2.2）制成玻璃融片分析样品。
由不均匀材料组成的、无需或难以进一步机械拆分的非均质样品，将样品切割破碎，经液氮冷冻，用研磨机将破碎后的样品研磨成粒径不超过1mm的粉末状样品，混匀，用硼酸（3.2.1）衬底压片制样，厚度不小于1mm，或用无水四硼酸锂（3.2.2）制成玻璃融片分析样品。
3.4.2.2 液体样品。移取一定体积的液体样品加入到液体专用样品杯里（样品厚度至少15mm），杯底部用6mm厚的聚脂膜支撑，杯上用带孔的盖盖住。
3.5 分析步骤
3.5.1 仪器准备。
按照仪器的操作规程开启仪器，并预热仪器直到仪器稳定。
3.5.2 分析谱线。
X射线荧光光谱法分析铬元素推荐选择Kα分析线。
3.5.3 工作曲线的绘制。
选择与待测样品基体相匹配的标准物质，按照X射线荧光光谱仪的测量条件，测定标准物质中铬元素的荧光强度，根据标准物质所给定的标准值和光谱仪所测得的强度绘制工作曲线。
3.5.4 校验。
在每次测试样品前，应用含铬元素的标准物质（3.2.4）校正工作曲线。
3.5.5 样品测试。
将制备好的样品放入样品室内，按选定的模式对样品进行分析，每个样品至少分析两次。
3.6 结果分析
3.6.1 结果计算。
将测定的铬元素谱线强度，按选定的分析模式计算出样品中铬元素的含量。
3.6.2 六价铬的筛选。
按《汽车禁用物质要求》标准中六价铬（在此按总铬量计）限值为质量分数0.1%（1000mg/kg），设定汽车材料中铬的筛选限值（表1），根据筛选限值对汽车材料中的铬元素进行筛选，结果有两种情况：
合格（P）——分析结果都低于设定的最低限，则结果为合格；
不确定（X）——分析结果高于设定的最低限值，则结果为不确定，需要进行六价铬的规定。
表1 汽车材料中铬含量的筛选限值 mg/kg
样品类别 聚合物材料 其他材料
筛选限值 P≤700-3S
QC/T 942-2013 引用如下标准： |
QC/T 942-2013被如下标准引用：
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