GB/T 38405.1-2025 Leather and fur—Determination of chlorinated hydrocarbons—Part 1：Short-chain chlorinated paraffins（SCCPs） English
1 Scope
This document specifies the test method to determine the amount of short-chain chlorinated paraffins (SCCPs) (C₁₀~Ci₃) in leather and fur.
This standard is applicable to the determination of the amount of SCCPs in various leathers, furs and their products.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 39364 Leather - Chemical, physical and mechanical and fastness tests - Sampling location (GB/T 39364-2020, ISO 2418:2017, MOD)
QB/T 1267 Fur - Chemical, physical and mechanical and fastness tests - Sampling location
QB/T 1272 Fur - Preparation of chemical test samples
QB/T 2716 Leather - Preparation of chemical test samples
3 Terms and definitions
No terms and definitions are specified in this document.
4 Principle
The sample is ultrasonically extracted using n-hexane under specified conditions. The extract is then purified with sulfuric acid and analyzed using gas chromatograph fitted to a mass selective detector with chemical ionization (GC-ECNI-MS) for determination and quantified by internal standard method.
A liquid chromatography system with single quad (LC-MS) can also be used if the user has demonstrated that the accuracy of measurement is equivalent to that of the GC-ECNI-MS method, see Annex C.
Note: In some cases when determining SCCPs using the GC-ECNI-MS method, the presence of sulfochlorinated paraffins and equivalent chain-length chloroalkenes causes interference. The Annex C procedure with a LC-MS method aims to give a better resolution and eliminate possible false positives determined with the GC-ECNI-MS method.
5 Reagents and materials
5.1 Unless otherwise specified, analytical grade reagents are adopted.
5.2 N-hexane: Chromatographically pure.
5.3 Internal standard solution, lindane, CAS No. 58-89-9, 1000 g/ml, N-hexane solvent.
5.4 Standard solutions, SCCPs (C₂₀~C₁₃, CAS No. 85535-84-8), with different chlorination degree, each 100 ug/mL.
- SCCPs (C₁₀~C₁₃), 55.5 % Cl;
- SCCPs (C₁₀~C₁₃), 63.0 % Cl.
5.5 SCCPs standard solution (50 μg/mL, 59% Cl): Pipette 533 μL of SCCPs (C1₀~C₁₃) 55.5% Cl standard solution (5.4) and 467 μL of SCCPs (C₁₀~C₁₃) 63% Cl standard solution (5.4) into a 2 mL volumetric flask (6.5). Add 20 μL of the internal standard solution (5.3) and fill the flask up to the volume with n-hexane (5.2). Other standard solutions with appropriate concentrations may also be used, with the internal standard concentration of 10 μg/mL.
5.6 Concentrated sulfuric acid, p=1.84g/Ml (20℃).
6 Apparatus
6.1 Analytical balance: weighing to an accuracy of 0.1 mg.
6.2 Sealable vessel, with lid, 20 mL, suitable for extraction with n-hexane.
6.3 Ultrasonic bath, with a controllable temperature of (60±5)°C.
Note: A frequency of 40 KHz is suitable.
6.4 Pipette, various capacity.
6.5 Volumetric flask: 2 mL.
6.6 Gas chromatograph and mass selective detector with chemical ionization, (GC-ECNI-MS).
6.7 Shaker or agitator, or other appropriate mixers, ensuring an efficient mixing of the phases.
7 Sampling and sample preparation
7.1 Sampling
Leather shall be sampled in accordance with GB/T 39364.
Fur shall be sampled in accordance with QB/T 1267. Avoid damage to the fur during sampling and keep it intact.
If it is not possible to take samples from standard positions (e.g. directly from shoes or garments), samples shall be taken from any available area. The test specimens shall be representative and this shall be stated in the test report.
Glue residuals shall be physically removed from the samples.
7.2 Preparation of samples
Prepare the leather samples in accordance with QB/T 2716.
Prepare the fur samples in accordance with QB/T 1272. The samples shall be tested together with fur.
8 Test procedures
8.1 Extraction
Weigh (0.5±0.001)g samples with the analytical balance (6.1) into the sealable vessel (6.2). Add 9.9 mL n-hexane (5.2) and 100 μL internal standard (5.3) and seal the vessel. Extract the sample at (60±5) °C in an ultrasonic bath (6.3) for (60± 2)min. Cool down to room temperature (less than 27°C).
During extraction, ensure that the sample is completely submerged. If submersion is not possible, increase the amount of n-hexane and internal standard solution proportionally.
8.2 Purification
Add a 5.0 mL of the extracted hexane solution to a tight sealable vessel (6.2) and add 1.0 mL concentrated sulfuric acid (5.6). Shake the vessel (6.7) for 10 min. After separating of the phases (optionally with centrifugation), transfer the upper n-hexane phase into another container and add 1.0 mL of concentrated sulfuric acid (5.6) for further purification. Repeat the above procedure until the lower acid layer becomes clear or white. This process shall not exceed five repetitions. 1 mL of the upper hexane phase shall be taken for GC-ECNI-MS(6.6) analysis.
8.3 Chromatographic analyses
As the test result depends on the instruments used, it is impossible to give general parameters for the chromatographic analysis. Annex D provides examples of proven effective chromatographic analysis conditions.
9 Expression of results
9.1 Evaluation method
The peak shape evaluation (PSE) has been successfully tested and used. Examples for integration with PSE are presented in Annex E.
Sum up the peak areas of four quantification ions from the standard and equate with the standard concentration. Sum up the peak areas of the samples too and the concentration is calculated with the response of the standard.
To check the linearity of the analytical system, a calibration standard as reference standard of known concentration is analysed after each ten samples and at the end of the sequence. The deviation in reference to the calibration standard shall be within ±20%, otherwise the analytical system has to be checked before retrying the analysis.
Sample extract should always be diluted in the concentration range of the standard.
The peak area integration of the sample solutions shall only be done in the retention time of the standard.
9.2 Ions used for quantification
Table D.1 lists the ions used for the quantification of SCCPs and the ions used for the internal standard lindane.
Sum up the quantifier peak areas from the standard and equate with the standard concentration. Sum up the quantifier peak areas of the sample, and calculate the SCCPs concentration in the sample solution with responses of the calibration standards.
To get a quantitative result, each peak area of the extract chromatogram has to be below the highest calibration point. If not, dilute the sample solution (8.2) with IS solution (5.3) or specify that the result is bigger than the calculated result.
9.3 Interferences during SCCPs determination
C₁Cl₇ quantifier ions (m/z 363) can show a large interference if there is a high MCCPs content. If the peak shape and retention time fits, it is possible to ignore the divergent quantifier/qualifier ratio. Note in test report.
C₁Cl₇ quantifier ions (m/z 375) can also show interference if there is a high MCCPs content. In this case the quantifier and qualifier can be switched. Note in test report.
9.4 Calculation of results
Set up the linear regression function by using the ratio (Asccp-s/AintStd-s) and (psccp-s/pint.Std-S) as shown in Formula (1).
(1)
where,
Asccp-s - the sum of the peak areas of SCCPs in the calibration standard;
psccp-s - the mass concentration of SCCPs in the calibration standard, μg/mL;
a - the slope of the linear function;
AintStd-s - the area of the internal standard in the calibration standard;
pint.Std-S - the mass concentration of internal standard in the calibration standard, μg/mL;
b - the intercept of the linear function;
The amount w of the SCCPs in the sample is calculated according to Formula (2), in mg/kg:
Contents
Foreword I
Introduction Ⅲ
1 Scope
2 Normative references
3 Terms and definitions
4 Principles
5 Reagents and materials
6 Apparatus
7 Sampling and sample preparation
8 Test procedures
9 Expression of results
10 Method feasibility
11 Test Report
Annex A (Informative) Comparison between this standard and ISO 18219-1:2021 in terms of clause number
Annex B (Informative) Technical differences between this document and ISO 18219-1:2021 and their justifications
Annex C (Informative) LC-MS analytical method
Annex D (Informative) Chromatographic analysis conditions
Annex E (Informative) Peak Shape Evaluation (PSE) in GC-ECNI-MS analysis
