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QC/T 1131-2020: Methods of Detecting Polycyclic Aromatic Hydrocarbons in Automotive Materials
QC/T 1131-2020
QC
AUTOMOBILE INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 43.040
T 40
Methods of Detecting Polycyclic Aromatic
Hydrocarbons in Automotive Materials
ISSUED ON: AUGUST 31, 2020
IMPLEMENTED ON: JANUARY 01, 2021
Issued by: Ministry of Industry and Information Technology of PRC
Table of Contents
Foreword ... 5
Introduction ... 6
1 Scope ... 7
2 Normative References ... 7
3 Terms and Definitions ... 8
4 Method-I: Gas Chromatography-Mass Spectrometry ... 9
5 Method-II: High Performance Liquid Chromatography ... 18
6 Method-III: Proton Nuclear Magnetic Resonance Spectroscopy ... 23
7 Test Report ... 27
Appendix A (Informative) Molecular Formulas, Relative Molecular Masses,
Characteristic Ions and Quantitative Selective Ions of 18 Polycyclic Aromatic
Hydrocarbons and 3 Internal Standard Substances... 28
Appendix B (Informative) Typical Gas Chromatography-Mass Spectrometry
Selective Ion Retention Time and Chromatogram of 18 Polycyclic Aromatic
Hydrocarbons and 3 Internal Standard Substances... 30
Appendix C (Informative) Liquid Chromatography Retention Time and
Chromatogram of 18 Polycyclic Aromatic Hydrocarbons ... 32
Bibliography ... 34
Methods of Detecting Polycyclic Aromatic
Hydrocarbons in Automotive Materials
Warning: The personnel using this Document shall have practical experience in
formal laboratory work. This Document does not point out all possible security
issues. 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 Document specifies the terms and definitions of the methods of detecting
polycyclic aromatic hydrocarbons in automotive materials, as well as the detection
methods of gas chromatography-mass spectrometry, high performance liquid
chromatography, proton nuclear magnetic resonance spectroscopy, and the like
contents.
This Document is applicable to the qualitative and quantitative testing of 18 polycyclic
aromatic hydrocarbons in automotive materials. Among them, gas chromatography-
mass spectrometry is suitable for testing polycyclic aromatic hydrocarbons in textiles,
plastics, thermoplastic elastomers, rubber and leather materials; high performance
liquid chromatography is suitable for testing polycyclic aromatic hydrocarbons in
plastics and rubber materials; proton nuclear magnetic resonance spectroscopy is
suitable for testing polycyclic aromatic hydrocarbons in rubber materials.
2 Normative References
The following documents are essential to the application of this document. For the
dated documents, only the versions with the dates indicated are applicable to this
document; for the undated documents, only the latest version (including all the
amendments) is applicable to this document.
GB/T 3516 Rubber - Determination of Solvent Extract
GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods
GB/T 29614-2013 Determination the Content of Polycyclic Aromatic
Hydrocarbons in Vulcanized Rubber Compounds
4 Method-I: Gas Chromatography-Mass Spectrometry
4.1 Method summary
After crushing, the specimen is added with organic solvent; extracted by ultrasonic or
microwave; if necessary, the extract is purified, concentrated, made constant volume,
and determined by gas chromatography-mass spectrometer (GC-MS), and qualitative
analysis is performed by retention time; use internal standard method or external
standard method to quantify.
4.2 Applicable material types
This method is suitable for the detection of polycyclic aromatic hydrocarbons in
materials such as textiles, plastics, thermoplastic elastomers, rubber and leather, etc.
4.3 Reagents and materials
4.3.1 n-hexane: chromatographically pure.
4.3.2 Toluene: chromatographically pure.
4.3.3 Acetone: chromatographically pure.
4.3.4 Dichloromethane: chromatographically pure.
4.3.5 Cyclohexane: chromatographically pure.
4.3.6 Sodium chloride: analytically pure.
4.3.7 Class-I water: comply with the provisions of GB/T 6682.
4.3.8 Helium gas: purity≥99.999%.
4.3.9 n-hexane + acetone (volume ratio 1: 1).
4.3.10 n-hexane + dichloromethane (volume ratio 3: 2).
4.3.11 Dimethyl sulfoxide: analytically pure, saturated by cyclohexane (see 4.3.5).
4.3.12 4% sodium chloride solution: 4g of sodium chloride (see 4.3.6) is dissolved in
100mL of Class-I water (see 4.3.7).
4.3.13 Silica gel solid phase extraction column: 500mg/3mL or equivalent; activate with
n-hexane (see 4.3.1) before use to keep it moist.
4.3.14 Standard solutions of 18 polycyclic aromatic hydrocarbons: purity≥95%.
4.4.7 Airtight microwave extractor.
4.4.8 Test tube with stopper.
4.4.9 Solid phase extraction device.
4.4.10 Rotary evaporator.
4.4.11 Thermometer: an accuracy of at least 1°C.
4.4.12 250mL separatory funnel.
4.4.13 Heating device: used to heat sodium chloride solution (see 4.3.12).
4.4.14 5mL volumetric flask.
4.4.15 Filter membrane: made of polytetrafluoroethylene, used to filter organic solvents,
with a pore size of 0.45µm or equivalent.
4.5 Preparation of specimen
Use scissors (or similar tools) to crush representative specimens into particles with a
particle size of less than 1mm and mix them. If necessary, use a liquid nitrogen crusher
(see 4.4.2) for crushing.
For the preparation of tire samples, refer to Appendix B in GB/T 29614-2013.
NOTE: In case of hard specimens, it is recommended to use a liquid nitrogen crusher for
crushing to prevent the loss of polycyclic aromatic hydrocarbons due to temperature rise during
the crushing process.
4.6 Extraction and purification
4.6.1 Extraction
4.6.1.1 Ultrasonic extraction
Weigh 0.2g of the specimen after cutting, accurate to 0.1mg; put it into a sealable
extraction container (see 4.4.4). Add 10mL (see Table 2) of extraction solvent with
mass concentration of internal standard substance 1 (see 4.3.15), internal standard
substance 2 (see 4.3.16) and internal standard substance 3 (see 4.3.17) of 50μg/L.
Fully soak the specimen; then seal the extraction container; and place it in an ultrasonic
water bath device (see 4.4.6); perform ultrasonic extraction at 60°C±2°C water
temperature for 60min±2min. After the extraction is completed, take out the extraction
container and cool to room temperature and mix well. If the extraction solution needs
to be purified, follow procedures in 4.6.2 for purification; if no purification is required,
place the extraction solution in a 35°C±2°C water bath and a vacuum of no less than
extraction column (see 4.3.13); and control the flow rate to 1 drop/2s. Then add 5mL
of n-hexane to rinse; discard the washing liquid. Elute the specimen by 5 mL of n-
hexane + dichloromethane (see 4.3.10) solution; and collect the eluate. Use a rotary
evaporator to evaporate the eluate to near dryness in a water bath of 35°C±2°C and a
vacuum of no less than 30kPa. Dissolve it by n-hexane + acetone and make constant
volume to 5mL. After being filtered by a filter membrane, the filtrate is analysed by a
gas chromatography-mass spectrometer. If necessary, analysis can be performed after
dilution.
4.6.2.2 Purification of thermoplastic elastomer specimens
Use a rotary evaporator (heating temperature no higher than 40°C) to concentrate the
extract prepared as per the procedures in 4.6.1 to about 1mL; add 10mL of
cyclohexane (see 4.3.5) to dissolve the specimen; transfer the dissolved specimen to
a separatory funnel (see 4.4.12) that has added 8 mL of dimethyl sulfoxide (see 4.3.11);
shake vigorously for about 1 min; centrifuge or stand for stratification. Then transfer
the lower layer of dimethyl sulfoxide phase to another separatory funnel. The residue
liquid is extracted by 8 mL of dimethyl sulfoxide once more; combine the extracts; and
discard the cyclohexane layer. Add 5mL of cyclohexane and 80mL of sodium chloride
solution (see 4.3.12) to the dimethyl sulfoxide extract; shake vigorously for 2min; and
let stand for stratification. Put the lower layer of aqueous phase into another separatory
funnel; and then repeat the extraction of the lower layer of aqueous phase by 5 mL of
cyclohexane once; combine the extracts; and discard the lower layer of aqueous phase
obtained during the second time. The extract was washed twice by 5 mL of 70°C
sodium chloride solution; and discard the aqueous layer. Combine the cyclohexane
layers; use a rotary evaporator to evaporate to near dryness in a water bath of
35°C±2°C and a vacuum of no less than 30kPa; and use toluene (see 4.3.2) to make
the constant volume to 5mL. After being filtered by a filter membrane, the filtrate is
analysed by a gas chromatography-mass spectrometer. It can be analysed after
dilution, if necessary.
4.6.2.3 Purification of rubber specimen
After cooling the extract prepared according to the procedures in 4.6.1 to room
temperature, it is transferred to the solid phase extraction column; and the flow rate is
controlled to 1 drop/2s. Then rinse by 5mL of n-hexane and discard the eluent. Elute
the specimen by 5 mL of n-hexane + dichloromethane solution; and collect the eluate.
In a water bath of 35°C±2°C and a vacuum of no less than 30kPa, use a rotary
evaporator to evaporate the eluate to near dryness; and make constant volume to 5mL
by toluene. After filtering through a filter membrane, the filtrate is analysed by a gas
chromatography-mass spectrometer. It can be analysed after dilution, if necessary.
4.7 Analysis method
4.7.1 Measurement conditions
Perform gas chromatography-mass spectrometry analysis on a mixed standard
working solution with no less than 5 concentration gradients; and take the ratio of the
mass concentration of polycyclic aromatic hydrocarbons to the mass concentration of
internal standard substances as the abscissa, and take the ratio of peak area of
polycyclic aromatic hydrocarbons to the peak area of the corresponding internal
standard substances as the ordinate to establish the internal standard curve. The linear
correlation coefficient of the internal standard curve shall be no less than 0.995.
4.8.2 Drawing of external standard curve
Perform gas chromatography-mass spectrometry analysis on a mixed standard
working solution with no less than 5 concentration gradients; and take the mass
concentration of polycyclic aromatic hydrocarbons in the mixed standard working
solution as the abscissa, and take the chromatographic peak area of the polycyclic
aromatic hydrocarbons in the mixed standard working solution as the ordinate to
establish an external standard curve. The linear correlation coefficient of the external
standard curve shall be no less than 0.995.
4.9 Blank test
Perform blank test without adding a specimen according to the procedure
requirements from 4.1 to 4.8.
4.10 Calculation of results
4.10.1 Quantitative calculation of internal standard method
Calculate the concentration of polycyclic aromatic hydrocarbons in the specimen
solution according to Formula (1):
Where:
ci – mass concentration of the ith polycyclic aromatic hydrocarbon in the specimen
solution, in µg/L;
Ki – slope of internal standard curve of the ith polycyclic aromatic hydrocarbon;
Ai – peak area of the ith polycyclic aromatic hydrocarbon in the specimen solution;
As – peak area of the internal standard substance corresponding to the ith polycyclic
aromatic hydrocarbon in the specimen solution;
bi – intercept of internal standard curve of the ith polycyclic aromatic hydrocarbon;
5 Method-II: High Performance Liquid Chromatography
5.1 Method summary
After crushing, the specimen is added with appropriate solvent and extracted by
microwave. If necessary, the extract is purified by a silica gel solid phase extraction
column, concentrated and made to constant volume; and then measured by high
performance liquid chromatograph (HPLC) and quantified by external standard method.
5.2 Types of applicable material
This method is suitable for testing polycyclic aromatic hydrocarbons in materials such
as plastics and rubber.
5.3 Reagents and materials
5.3.1 Acetonitrile: chromatographically pure.
5.3.2 n-hexane: chromatographically pure.
5.3.3 Acetone: chromatographically pure.
5.3.4 Dichloromethane: chromatographically pure.
5.3.5 Class-I water: meet the requirements of GB/T 6682.
5.3.6 n-hexane + acetone (volume ratio 1: 1).
5.3.7 n-hexane + dichloromethane (volume ratio 3: 2).
5.3.8 Silica gel solid phase extraction column: 500mg/3mL or equivalent, activate with
n-hexane (see 5.3.2) before use to keep it moist.
5.3.9 Standard solutions of 18 polycyclic aromatic hydrocarbons: purity ≥95%.
5.3.10 Preparation of mixed standard working solution: Pipette an appropriate amount
of 18 PAHs mixed standard solution (see 5.3.9); and dilute it by acetonitrile (see 5.3.1)
into series of standard working solutions with mass concentration range of 2.5 µg/L~
250µg/L.
5.4 Apparatus
5.4.1 High performance liquid chromatograph: equipped with suitable detectors such
as ultraviolet-visible detector and diode array detector.
5.4.2 Liquid nitrogen crusher: equipped with a screen with an aperture of 1mm.
the supernatant. The precipitate is washed twice by 5mL of n-hexane; and the
supernatants obtained from the two centrifugation operations are combined after
centrifugation. The supernatant is concentrated to near dryness by a rotary evaporator;
and add 2mL of n-hexane to shake and dissolve; and the resulting solution is
transferred to a solid phase extraction column (see 5.3.8); and the flow rate is
controlled to 1 drop/2s. Then rinse by 5mL of n-hexane and discard the eluent. Elute
by 5mL of n-hexane + dichloromethane (see 5.3.7) solution; collect the eluate; use a
rotary evaporator to concentrate to near dryness; dissolve by acetonitrile and make
constant volume to 10mL. Filter through a filter membrane (see 5.4.11), then the filtrate
is analysed by high performance liquid chromatograph (see 5.4.1), and it can be
analysed after dilution, if n...