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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).
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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
汽車材料中六價鉻的檢測方法
1 范圍
本標準規(guī)定了汽車零部件及材料中六價鉻含量的檢測應(yīng)運。其中：
“X射線熒光光譜法”適用于采用X射線熒光光譜法篩選和快速判定汽車材料中六價鉻的含量。
“金屬防腐鍍層中六價鉻定性試驗”適用于采用點滴試驗法和沸水萃取法定性確定汽車車防腐鍍層中六價鉻的存在。“金屬防腐鍍層中六價鉻含量測定”適用于采用沸水萃取、比色法定量測定防腐鍍層中六價鉻的含量。“金屬防腐鍍層中六價鉻定性試驗”和“金屬防腐鍍層中六價鉻含量測定”適用于無附加覆蓋層（例如：油膜、水基或溶劑型聚合物膜或蠟?zāi)ぃ┑腻儗印?“聚合物材料和電子材料中六價鉻含量測定”適用于采用堿液萃取、比色法測定汽車聚合物材料和汽車電子材料中六價鉻的含量，不適用于聚乙烯（PE）和乙稀-乙酸乙烯酯共聚物（EVAC）材料。其他汽車材料，如玻璃、陶瓷、織物和油漆涂層中的六價鉻含量參照本方法測定。
“皮革材料中六價鉻含量測定”適用于采用磷酸鹽液萃取、比色法測定汽車皮革材料中六價鉻的含量。
2 規(guī)范性引用文件
下列文件對于本文件的應(yīng)用是必不可少的。凡是注日期的引用文件，僅注日期的版本適用于本文件。凡是不注日期的引用文件，其最新版本（包括所有的修改單）適用于本文件。
GB/T 1839 鋼產(chǎn)品鍍鋅層質(zhì)量試驗方法（GB/T 1839-2008，ISO 1460：1992，MOD）
GB/T 8170 數(shù)值修約規(guī)則與極限數(shù)值的表示和判定
GB/T 20017 金屬和其他無機覆蓋層 單位面積質(zhì)量的測定 重量法和化學分析法評述（GB/T 20017-2005，ISO 10111：2000，IDT）
GB/T 30512-2014 汽車禁用物質(zhì)要求
GB/T 21277-2007 電子電氣產(chǎn)品中限用物質(zhì)鉛、汞、鉻、鎘和溴的快速篩選 X射線熒光光譜法
QB/T 2262-1996 皮革工業(yè)術(shù)語
QB/T 2706 皮革 化學、物理、機械和色牢度試驗 取樣部位（QB/T 2706-2005，ISO 2418：2002，MOD）
IEC 62321：2008 Ed.1.0 電子電氣產(chǎn)品 六種限制物質(zhì)（鉛、汞、鎘、六價鉻、多溴聯(lián)苯和多溴聯(lián)苯醚）的規(guī)定
ISO 3613：2000 鋅、鎘、鋁—鋅合金及鋅—鋁合金表面鉻酸鹽的轉(zhuǎn)化鍍層—測試方法
EN ISO 17075：2007 皮料鉻（六價鉻）含量測試
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3 X射線熒光光譜法
3.1 原理
將制備好的樣品置于X射線熒光光譜儀樣品室內(nèi)，按所選定的分析模式對樣品中的鉻含量進行X射線熒光光譜分析，并根據(jù)篩選限值判斷樣品中鉻含量是否合格，以及是否需要進行精確測定。
注：X射線熒光光譜分析所得結(jié)果是樣品所含的總鉻而非六價鉻。
3.2 試劑和材料
3.2.1 硼酸：優(yōu)級純，105℃烘1h，儲存于干燥內(nèi)。
3.2.2 無水四硼酸鋰：優(yōu)級純，700℃灼燒4h，儲存于干燥器內(nèi)。
3.2.3 液氮：工業(yè)級。
3.2.4 含鉻元素的標準物質(zhì)。
3.3 儀器和設(shè)備
3.3.1 X射線熒光光譜儀。
3.3.2 切割機。
3.3.3 液氮低溫粉碎機。
3.3.4 研磨機：帶碳化鎢（WC）磨具。
3.3.5 壓片機：工作壓力不小于20MPa。
3.3.6 熔樣機：工作溫度不低于1150℃。
3.4 樣品制備
3.4.1 樣品制備原則。
3.4.1.1 用于分析的樣品必須覆蓋光譜儀的測量窗口。
3.4.1.2 樣品的照射面應(yīng)能代表樣品整體。
3.4.1.3 樣品制備過程中應(yīng)注意防止污染。
3.4.2 樣品制備方法。
3.4.2.1 固體樣品。表面平整、大小適合X射線熒光光譜儀要求的均質(zhì)樣品，直接分析。小樣品可匯在一起進行分析。薄樣品，可將其疊在一起達到足夠厚（厚度至少5mm），需特別注意樣品厚度的一致性及組成的均勻性。分析時為使樣品平整鋪開，可加內(nèi)襯材料作為支撐物，應(yīng)盡量選用背景低的內(nèi)襯材料。
各種塊、板等不定形的樣品以及尺寸過大的樣品，可用切割機、研磨機等將其加工至合適尺寸。小樣品（如塑料顆粒等）通過液氮冷凍、機械粉碎再經(jīng)壓片機壓片制成分析樣品。
玻璃、陶瓷等易碎樣品先粉碎成小塊，再研磨成小于200目（0.074mm）的粉末，混勻，用硼酸（3.2.1）襯底壓片制樣，厚底不小于1mm，或用無水四硼酸鋰（3.2.2）制成玻璃融片分析樣品。
由不均勻材料組成的、無需或難以進一步機械拆分的非均質(zhì)樣品，將樣品切割破碎，經(jīng)液氮冷凍，用研磨機將破碎后的樣品研磨成粒徑不超過1mm的粉末狀樣品，混勻，用硼酸（3.2.1）襯底壓片制樣，厚度不小于1mm，或用無水四硼酸鋰（3.2.2）制成玻璃融片分析樣品。
3.4.2.2 液體樣品。移取一定體積的液體樣品加入到液體專用樣品杯里（樣品厚度至少15mm），杯底部用6mm厚的聚脂膜支撐，杯上用帶孔的蓋蓋住。
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3.5 分析步驟
3.5.1 儀器準備。
按照儀器的操作規(guī)程開啟儀器，并預(yù)熱儀器直到儀器穩(wěn)定。
3.5.2 分析譜線。
X射線熒光光譜法分析鉻元素推薦選擇Kα分析線。
3.5.3 工作曲線的繪制。
選擇與待測樣品基體相匹配的標準物質(zhì)，按照X射線熒光光譜儀的測量條件，測定標準物質(zhì)中鉻元素的熒光強度，根據(jù)標準物質(zhì)所給定的標準值和光譜儀所測得的強度繪制工作曲線。
3.5.4 校驗。
在每次測試樣品前，應(yīng)用含鉻元素的標準物質(zhì)（3.2.4）校正工作曲線。
3.5.5 樣品測試。
將制備好的樣品放入樣品室內(nèi)，按選定的模式對樣品進行分析，每個樣品至少分析兩次。
3.6 結(jié)果分析
3.6.1 結(jié)果計算。
將測定的鉻元素譜線強度，按選定的分析模式計算出樣品中鉻元素的含量。
3.6.2 六價鉻的篩選。
按《汽車禁用物質(zhì)要求》標準中六價鉻（在此按總鉻量計）限值為質(zhì)量分數(shù)0.1%（1000mg/kg），設(shè)定汽車材料中鉻的篩選限值（表1），根據(jù)篩選限值對汽車材料中的鉻元素進行篩選，結(jié)果有兩種情況：
合格（P）——分析結(jié)果都低于設(shè)定的最低限，則結(jié)果為合格；
不確定（X）——分析結(jié)果高于設(shè)定的最低限值，則結(jié)果為不確定，需要進行六價鉻的規(guī)定。
表1 汽車材料中鉻含量的篩選限值 mg/kg
樣品類別 聚合物材料 其他材料
篩選限值 P≤700-3S
QC/T 942-2013 引用如下標準： |
QC/T 942-2013被如下標準引用：
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