Standard No.:	QC/T 942-2013
English Name:	Test Method for Hexavalent Chromium in Automobile Materials
Chinese Name:	汽车材料中六价铬的检测方法
Chinese Classification:	T05    Special materials and their products
Professional Classification:	QC    Professional Standard - Automobile
Issued by:	Ministry of Industry and Information Technology
Issued on:	2013-10-17
Implemented on:	2014-3-1
Status:	superseded
Superseded by:	QC/T 942-2021 Test methods of hexavalent chromium in automotive materials
Superseded on:	2022-2-1
Language:	English
File Format:	PDF
Word Count:	12000 words
Price(USD):	340.0
Delivery:	via email in 1 business day

Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative. 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