GB/T 46974-2025Footwear - Chemical tests - Determination of short-chain chlorinated paraffins (English PDF)

3.1 Short-chain chlorinated paraffins; SCCPs

A mixture of chlorinated straight-chain alkanes with 10 ~ 13 carbon atoms, obtained by chlorinating different n-alkanes.

5.1 Toluene

CAS No.: 108-88-3, analytically pure.

5.2 n-Hexane

CAS No.: 110-54-3, chromatographically pure.

5.3 Concentrated Sulfuric Acid

98% (mass fraction), rho = 1.84 g/mL (20 °C), CAS No.: 7664-93-9, analytically pure.

5.4 Internal Standard

epsilon-1,2,3,4,5,6-hexachlorocyclohexane (CAS No.: 6108-10-7) or gamma-1,2,3,4,5,6-hexachlorocyclohexane (Lindane, CAS No.: 58-89-9), chromatographically pure.

5.5 Standard Solutions

5.5.1 SCCPs, chlorine content 51.5% (51.5% Cl), CAS No.: 85535-84-8, industrial grade, rho = 100 µg/mL in n-hexane.

5.5.2 SCCPs, chlorine content 55.5% (55.5% Cl), CAS No.: 85535-84-8, industrial grade, rho = 100 µg/mL in n-hexane.

5.5.3 SCCPs, chlorine content 63.0% (63.0% Cl), CAS No.: 85535-84-8, industrial grade, rho = 100 µg/mL in n-hexane.

5.5.4 Internal standard solution, n-hexane solution of internal standard (5.4), rho = 100 µg/mL.

5.6 Polytetrafluoroethylene Filter Membrane

0.45 µm.

8.1 Extraction

Accurately weigh-take (1.0 ± 0.1) g of representative sample fragments (Chapter 7) into the extractor (6.3), accurate to 0.1 mg. For non-leather samples, add 10.0 mL of toluene (5.1), and for leather samples, add 10.0 mL of n-hexane (5.2), wet the entire sample, and use a PTFE stopper to seal the extractor (6.3). If the test sample is not completely immersed in the extraction solution, then, continue adding toluene (5.1) or n-hexane (5.2), until the sample is completely wetted.

In an ultrasonic extractor (6.4), ensure that the extractor (6.3) is sealed, extract at (60 ± 5) °C for (60 ± 5) min, then, cool to room temperature.

8.2 Purification

8.2.1 For the toluene extraction solution, transfer-take 5.0 mL, and use a nitrogen blowing instrument (6.5) or a rotary evaporator (6.6) to evaporate the extraction solution to dryness (free of toluene) at (55 ± 5) °C. Use a vortex mixer (6.7) to dissolve the residue after nitrogen blowing in 1.96 mL of n-hexane (5.2), and add 40 µL of internal standard solution (5.5.4).

8.2.2 For the n-hexane extraction solution, transfer-take 1.96 mL and add 40 µL of internal standard solution (5.5.4).

8.2.3 Slowly add 2.0 mL of concentrated sulfuric acid (5.3) to the extraction solution (8.2.1 or 8.2.2), use a horizontal oscillator (6.8) to oscillate it, so as to ensure thorough mixing of the two phases. After oscillating for 30 minutes, if necessary, use a centrifuge (6.9) to centrifuge it.

Filter the supernatant through a polytetrafluoroethylene (PTFE) filter membrane (5.6) and reserve it for later testing.

8.3 Calibration

For practical considerations, use SCCPs with varying chlorine contents to respectively prepare solutions of different concentrations for calibration. Based on this, appropriate SCCPs calibration solutions need to be prepared. Each solution with different chlorine contents contains different amounts of the target compound and an equal amount of internal standard, using n-hexane as the solvent.

Recommended calibration solution preparations are shown in Table 1 ~ Table 5. A summary of all calibration measurement points is shown in Table 6. […]