GB/T 42705-2023 PDF English
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Textiles - Determination of benzene residues
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GB/T 42705-2023: Textiles - Determination of benzene residues---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT42705-2023
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 59.080.01
CCS W 04
Textiles - Determination of benzene residues
ISSUED ON: MAY 23, 2023
IMPLEMENTED ON: MARCH 1, 2024
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 4
4 Principles ... 4
5 Reagents ... 4
6 Instruments and equipment ... 5
7 Test steps ... 5
8 Calculation of results ... 7
9 Limit of quantitation and precision ... 7
10 Test report ... 7
Appendix A (Informative) Headspace-GC-MS reference conditions ... 9
Textiles - Determination of benzene residues
WARNING -- The personnel using this document shall have practical experience
in formal laboratory work. This document does not indicate all possible safety
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 describes a method for the determination of benzene residues in textile
products by using a headspace-gas chromatograph-mass spectrometer (HS-GC-MS).
This document applies to all types of textile products.
2 Normative references
This document does not have normative references.
3 Terms and definitions
This document does not have terms and definitions that need to be defined.
4 Principles
The sample is placed in an airtight container, and the benzene in the sample volatilizes
into the container after equilibrating at the specified temperature and time. The air in
the upper layer of the container is extracted and injected into a gas chromatograph-mass
spectrometer for measurement, and the standard curve of the internal standard method
is used for quantification.
5 Reagents
5.1 Methanol (CAS No. 67-56-1): chromatographically pure.
5.2 Benzene (CAS No. 71-43-2) standard solution: 1000 mg/L, or a standard solution
of other appropriate concentrations.
5.3 Standard solution of deuterated toluene (toluene-d8, CAS No. 2037-26-5): 1000
mg/L, or a standard solution of other suitable concentrations.
5.4 Benzene standard stock solution (10 mg/L, 20 mg/L, 50 mg/L, 100 mg/L, 200 mg/L):
Pipette 100 μL, 200 μL, and 400 μL of 1000 mg/L benzene standard solution (5.2) into
three 2 mL volumetric flasks respectively, dilute to the mark with methanol (5.1), and
mix well to obtain standard stock solutions of 50 mg/L, 100 mg/L, and 200 mg/L; take
the benzene standard stock solution of 200 mg/L prepared above, and pipette 100 μL
and 200 μL into two 2 mL volumetric flasks respectively, dilute to the mark with
methanol (5.1), and mix well to obtain 10 mg/L and 20 mg/L standard stock solutions.
5.5 Internal standard working solution (100 mg/L): Accurately pipette 200 μL of
deuterated toluene standard solution (5.3) into a 2 mL volumetric flask, dilute to the
mark with methanol (5.1), and mix well.
NOTE 1: Store the above standard solution in a refrigerator at (-18±4) °C. The benzene standard solution
(5.2) and deuterated toluene (5.3) standard solution are valid for 3 months after opening or use. Benzene
standard storage solution (5.4) and internal standard working solution (5.5) are valid for 1 week.
NOTE 2: When preparing the solution, other volumetric flasks of appropriate volume can also be used.
6 Instruments and equipment
6.1 Headspace-gas chromatograph-mass spectrometer (HS-GC-MS): It shall be
equipped with an electron bombardment ion source (EI).
6.2 Headspace vial: The capacity is 20 mL; it has a PTFE-coated sealing cap.
6.3 Pipettor or microinjector: 100 μL, 1000 μL, 5000 μL, etc.
6.4 Brown volumetric flask: 2 mL.
6.5 Analytical balance: The graduation values are 0.0001 g and 0.01 g.
7 Test steps
7.1 Sample preparation
Take a representative sample, cut it into fragments smaller than 5 mm×5 mm, and mix
them; weigh 0.5 g of sample from the fragments, accurate to 0.01 g, and place it in a 20
mL headspace vial (6.2).
7.2 Adding internal standard
Pipette 50 μL of the internal standard working solution (5.5), put it into the headspace
vial containing the sample, and immediately seal it tightly with a lid. Test it later.
7.3 Drawing of working curve
Take six 20 mL headspace vials (6.2), and add 50 μL internal standard working solution
(5.5) to each headspace vial. Add 50 μL of 10 mg/L, 20 mg/L, 50 mg/L, 100 mg/L, and
200 mg/L benzene standard stock solution (5.4) to 5 headspace vials that have been
added with the internal standard working solution, and immediately seal them with lids.
At this time, the working solutions with the total toluene-d8 mass of 5 μg and the total
benzene mass of 0 μg, 0.5 μg, 1 μg, 2.5 μg, 5 μg, and 10 μg respectively are obtained.
Carry out the measurement according to the provisions of 7.4; take the total amount of
benzene in the series of working solutions as the abscissa (in micrograms), take the
peak area ratio of benzene to toluene-d8 as the ordinate, and draw the working curve.
The correlation coefficient R2 of the obtained working curve shall be greater than 0.99.
NOTE: In order to reduce the volatilization of benzene as much as possible, when adding the standard
solution, pour it into the bottom of the bottle gently to avoid it from contaminating the bottle wall. After
adding the standard solution at each concentration point, immediately cover and seal the bottle; the
working curve solution shall be prepared newly when it will be used; after the standard stock solution is
taken out of the refrigerator, let it stand in a closed state and return to room temperature, and then carry
out the preparation work.
7.4 Headspace-gas chromatography-mass spectrometry analysis
The equilibration time of the automatic headspace sampler is 50 min, and the oven
temperature is 120 °C. Place the sample (7.2) to which the internal standard has been
added into the headspace sampler, and perform the determination referring to the
instrument conditions listed in Appendix A.
If the selected monitoring ions of the sample (7.2) to which the internal standard has
been added and that of the working curve (7.3) appear at the same retention time
(±0.5%), and the allowable deviation between the relative ion abundance of the
qualitative ion and the relative ion abundance of the working curve does not exceed the
range specified in Table 1, then it is qualitatively confirmed that the corresponding
target analyte exists in the sample.
Table 1 -- The allowable deviation range of relative ion abundance in the
qualitative confirmation
Relative ion abundance / % >50 >20~50 >10~20 ≤10
Allowable deviation range / % ±10 ±15 ±20 ±50
The internal standard curve method is used for quantification, and the total amount of
benzene in the sample is read from the working curve according to the peak area ratio
of benzene to toluene-d8 in the sample.
7.5 Blank test
Appendix A
(Informative)
Headspace-GC-MS reference conditions
A.1 Overview
Since the test results depend on the instrument used, it is impossible to give general
parameters for chromatographic analysis. The gas chromatography and mass
spectrometry conditions given in this appendix have been proven to be suitable.
A.2 Measurement conditions and parameters
A.2.1 The conditions of the automatic headspace sampler are as follows:
a) Quantitative loop temperature: 125 °C;
b) Quantitative loop volume: 1 mL;
c) Transfer line temperature: 220 °C;
d) Pressurization time: 0.2 min;
e) Injection time: 1 min.
A.2.2 Gas chromatography conditions are as follows:
a) Chromatographic column: a 6% cyanopropylphenyl-94% methylpolysiloxane
quartz capillary column, with a column length of 30 m, a film thickness of 1.8
μm, an inner diameter of 0.32 mm; or other chromatographic columns with
equivalent performance;
b) Headspace injector temperature: 250 °C;
c) Injection mode: split injection, with a split ratio of 10:1;
d) Temperature program: The initial temperature is 40 °C, and keep for 3 minutes;
heat up to 230 °C at 10 °C/min, and keep for 5 minutes;
e) Carrier gas: helium (the purity is ≥99.999%), and the flow rate is 1.5 mL/min
(constant flow mode).
A.2.3 Mass spectrometry conditions are as follows:
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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