GB/T 38405.1-2025Leather and fur - Determination of chlorinated hydrocarbons - Part 1: Short-chain chlorinated paraffins (SCCPs) (English PDF)

6.6 Gas chromatograph equipped with a mass spectrometric detector with an electron capture

negative ionization source (GC-ECNI-MS).

6.7 Oscillator or stirrer, or other suitable mixing equipment, for effective mixing of the phases.

7.1 Sampling

Sampling of leather shall be conducted in accordance with the provisions of GB/T 39364.

Sampling of fur shall be conducted in accordance with the provisions of QB/T 1267; during the sampling process, care shall be taken to avoid loss of the fur pile and to maintain its integrity.

If sampling cannot be performed from the standard designated area (e.g., when sampling directly from footwear or garments), samples shall be taken from any available area within the usable material; the test samples shall be representative, and this deviation shall be noted in the test report.

Any residual adhesive remaining on the sample shall be removed using physical methods.

7.2 Preparation of Test Samples

Preparation of leather test samples shall be conducted in accordance with the provisions of

QB/T 2716.

Preparation of fur test samples shall be conducted in accordance with the provisions of QB/T

1272; the test samples shall be tested together with the fur pile attached.

8.1 Extraction

Weigh (0.5±0.001) g of the test sample using an analytical balance (6.1) into a stoppered, sealed container (6.2). Add 9.9 mL of n-hexane (5.2) and 100 µL of the internal standard solution (5.3), then seal the container. Place the test sample in an ultrasonic generator (6.3) and extract it at (60±5)°C for (60±2) min. Allow the test sample to cool to room temperature (below 27°C).

During extraction, ensure that the test sample is completely submerged; if complete submersion cannot be achieved, the volumes of n-hexane and internal standard solution may be increased proportionally.

8.2 Purification

Transfer 5.0 mL of the n-hexane extract into a stoppered, sealed container (6.2). Add 1.0 mL of concentrated sulfuric acid (5.6) and shake the mixture on an oscillator (6.7) for 10 min. Once the two phases have separated (which may be facilitated by centrifugation), transfer the upper n-hexane phase to a separate container. Add 1.0 mL of concentrated sulfuric acid (5.6) to perform a further purification step. Repeat this procedure until the lower acid layer becomes clear or turns white; this process must not be repeated more than five times. Take 1 mL of the upper n-hexane phase for GC-ECNI-MS (6.6) analysis.

8.3 Chromatographic Analysis

Since the test results depend on the instrumentation used, universal parameters for chromatographic analysis cannot be specified. Appendix D provides examples of chromatographic conditions that have been proven effective.

9.1 Evaluation Methods

Peak shape evaluation (PSE) has been successfully tested and applied; Appendix E provides the examples of integration using PSE.

The peak areas of the four quantitative ions in the standard solution are summed and correlated with the concentration of the standard solution. Concurrently, the peak areas obtained from the sample solutions are summed, and the concentration of the sample solution is calculated based on the response values obtained from the standard solution.

To verify the linearity of the analytical system, a standard solution of known concentration is analyzed as a reference standard after every 10 test samples or at the end of the analytical sequence. The deviation of the test results for the reference standard shall be within ±20%;

otherwise, the analytical system must be inspected before re-analyzing the samples.

Sample solutions should be diluted such that their concentrations fall within the concentration range of the standard solutions.

Peak area integration for sample solutions shall be performed within the retention time windows established for the standard solutions.

9.2 Quantitative Ions

Table D.1 lists the quantitative ions used for the determination of SCCPs and the internal standard, Lindane.

The peak areas obtained from the standard solutions are summed and correlated with the concentration of the standard solution. Concurrently, the peak areas obtained from the sample solutions are summed, and the concentration of SCCPs in the sample solution is calculated based on the response values obtained from the standard solution.

To obtain quantitative results, the peak area of each analyte in the sample solution must be lower than that of the highest calibration point; otherwise, the sample solution (8.2) shall be diluted using the internal standard solution (5.3), or the test report shall explicitly state that the test result exceeds the calculated range.

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