GB/T 33391-2026Footwear - Chemical tests - Determination of polycyclic aromatic hydrocarbons(PAHs) (English PDF)

5.1 General

Unless otherwise specified, all reagents shall be of analytical grade.

5.2 Toluene

CAS Registry Number. 108-88-3.

5.3 PAHs

Table 1 lists 24 relevant PAHs.

Table 1 -- List of Relevant PAHs

5.4 PAH Standard Solution (100 µg/mL)

The laboratory shall select the PAH species listed in Table 1 based on testing requirements and prepare a standard stock solution for each selected PAH (with a mass concentration of C=100

µg/mL for each PAH); these solutions shall be prepared using commercially available certified mixed standard samples/reference materials or certified single-component standard samples/reference materials.

5.5 PAHs - Stock Solution 1 (5 µg/mL)

Using a pipette (6.6), transfer 9 mL of toluene (5.2) into a 10 mL amber volumetric flask (6.7), add 500 µL of PAH standard solution (5.4), and dilute to the mark with toluene (5.2).

5.6 PAHs - Stock Solution 2 (0.5 µg/mL)

Using a pipette (6.6), transfer 8 mL of toluene (5.2) into a 10 mL amber volumetric flask (6.7), add 1 mL of stock solution 1 (5.5), and dilute to the mark with toluene (5.2).

5.7 Internal Standard Solution (100 µg/mL)

5.7.1 General

5.7.1.1 The internal standards (see 5.7.1.2 to 5.7.1.8) shall be commercially available certified mixed standard samples/reference materials or certified single-component standard samples/reference materials.

5.7.1.2 Naphthalene-d8, CAS Registry Number. 1146-65-2.

5.7.1.3 Fluorene-d10, CAS Registry Number. 81103-79-9.

5.7.1.4 Pyrene-d10, CAS Registry Number. 1718-52-1.

5.7.1.5 Chrysene-d12, CAS Registry Number. 1719-03-5.

5.7.1.6 Benzo[a]pyrene-d12, CAS Registry Number. 63466-71-7.

5.7.1.7 Benzo[g,h,i]perylene-d12, CAS Registry Number. 93951-66-7.

5.7.1.8 Dibenzo[a,h]anthracene-d14, CAS Registry Number. 13250-98-1.

5.7.2 Correspondence between PAHs and internal standards

Select the appropriate internal standards for PAH determination according to Table 2.The number of internal standards may be appropriately reduced if method validation demonstrates sufficient recovery for the corresponding PAHs.

Table 2 -- List of Relevant Internal Standards

5.7.3 Internal standards - Stock solution (mass concentration of 100 µg/mL each)

The internal standard may be a commercially available certified solution or a solution prepared from a certified single compound.

To prepare the internal standard solution, weigh 10 mg of each selected internal standard (5.7.1) using an analytical balance (6.2), place it in a 100 mL amber volumetric flask, and dilute to the mark with toluene (5.2).

5.7.4 Internal standards - Working solution (5 µg/mL)

Using a pipette (6.6), transfer 0.5 mL of each internal standards - stock solution (5.7.3) into a

10 mL amber volumetric flask, and dilute to the mark with toluene (5.2).

5.8 PAHs - Calibration Solutions

Prepare at least four PAH calibration solutions (see Table 3) of different concentrations containing the internal standard, using toluene as the solvent; the concentration range shall cover the requirements of the analytical method. Using a micropipette (6.5) or pipette (6.6), transfer an appropriate amount of PAHs - stock solution 1 (5.5) or PAHs - stock solution 2 (5.6) and 100 µL of internal standards - working solution (5.7.4) into a 10 mL amber volumetric flask (6.7), and dilute to the mark with toluene (5.2).

Table 3 -- Preparation of Calibration Standard Solutions Suitable for GC-MS (Example)

5.9 Internal Standard Extraction Solution (0.050 µg/mL)

Dilute the internal standards - stock solution (5.7.3) with toluene (5.2) in a volumetric flask of appropriate capacity to prepare an extraction solution with an internal standard mass concentration of 0.050 µg/mL. This solution shall be stored in an amber flask in a dark place, avoiding exposure to direct sunlight. The shelf life of this solution is 7 d.

5.10 Storage

All PAH standard solutions (5.4, 5.5, 5.6) and internal standard solutions (5.7.3, 5.7.4) shall be stored in amber glassware in a refrigerator at approximately (5±3)°C, protected from light.

6.1 Except for the instruments listed below, the conventional laboratory apparatus and amber

laboratory glassware used shall comply with the requirements of GB/T 12810.

NOTE. Plastic equipment may contain trace amounts of PAHs.

6.2 Analytical balance, with a readability of at least 0.1 mg.

6.3 Amber glass extraction flask, with a screw cap (e.g., volume of 40 mL).

6.4 Ultrasonic water bath, equipped with a temperature control device capable of maintaining

(60±5)°C.

6.5 Micropipettes, 50 µL and 100 µL.

6.6 Pipettes, 0.5 mL to 5 mL.

6.7 Amber volumetric flasks (e.g., 10 mL and 100 mL).

6.8 Gas chromatograph, equipped with a single quadrupole mass spectrometer (GC-MS) or a

triple quadrupole mass spectrometer (GC-MS/MS).

6.9 Polytetrafluoroethylene (PTFE) membrane filter, pore size 0.45 µm.

6.10 Amber GC-MS autosampler vials, with caps (e.g., volume of 2 mL).

8.1 Extraction

Weigh (0.500±0.100) g of the sample into an amber glass extraction flask (6.3) using an analytical balance (6.2). Record the mass to the nearest 1 mg. Using a pipette (6.6), transfer 10 mL of the internal standard extraction solution (5.9) into an amber glass extraction flask (6.3) and seal it with a cap.

Place the flask in an ultrasonic water bath (6.4) maintained at (60±5)°C and extract for (60±5) min.

After the extraction solution has cooled to below 27°C, filter it using a PTFE membrane filter (6.9).

Transfer a specific volume of the extraction solution into an amber GC-MS autosampler vial (6.10) and seal it with a cap.

8.2 Optional Procedure. Solid-Phase Extraction (SPE) Cleanup

If matrix interference is present, cleanup may be performed using an SPE column that is highly selective for PAHs and compatible with toluene.

8.3 GC-MS or GC-MS/MS Determination

Calibrate the GC-MS or GC-MS/MS (6.8) using at least four calibration solutions of different concentrations (5.8) and determine the extracted PAHs.

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