GB/T 39113-2020Footwear - Critical substances potentially present in footwear and footwear components - Determination of phenol (English PDF)

5.1 Chemicals

The substances mentioned in this standard should be used with limited purity.

---The purity of the product used for the standard is above 95%;

---The solvent is analytically pure.

5.1.1 Phenol CAS. 108-95-2 (target compound).

5.1.2 Phenol-D6CAS. 13127-88-3 (extraction substitute).

5.1.3 Anthracene-D10CAS. 1719-06-8 (internal standard).

5.1.4 Toluene CAS. 108-88-3 (solvent).

5.1.5 Acetone CAS. 67-64-1 (solvent).

5.1.6 A mixture of toluene/acetone with a volume ratio of 80/20 (mixed extract).

The composition of the mixture is based on volume. For example, to prepare a 100mL mixture, 80mL of toluene and 20mL of acetone need to be mixed.

5.1.7 Methanol CAS. 67-56-1 (solvent).

5.2 Stock solution

5.2.1 Internal standard anthracene-D10 stock solution (1000mg/L)

Weigh 10mg of anthracene-D10 in a 10mL volumetric flask and dilute with acetone. Then transfer the prepared solution to PTFE

(PTFE) stopper in a 10mL brown vial and store at 4°C.

5.2.2 Internal Standard Anthracene-D10 Working Solution (10mg/L)

Prepare stock solution (5.2.1) 1.100 dilution. For example, take 100µL of stock solution in a 10mL volumetric flask and use acetone to make the volume constant.

5.2.3 Extraction substitute——phenol-D6 stock solution (1000mg/L)

Weigh 10mg of phenol-D6 in a 10mL volumetric flask and dilute with acetone. Then transfer the prepared solution to the PTFE stopper

In a 10mL brown vial, and store at 4°C.

5.2.4 Extraction Substitute——Phenol-D6 Working Solution (10mg/L)

Prepare stock solution (5.2.3) 1.100 dilution. For example, take 100µL of stock solution in a 10mL volumetric flask and use acetone to make the volume constant.

5.2.5 Target compound-phenol-stock solution (1000mg/L)

Weigh 10mg of phenol in a 10mL volumetric flask and dilute with acetone. Then transfer the prepared solution to the one with PTFE stopper

10mL brown vial and store at 4°C.

5.2.6 Phenol Phenol-D6-Calibration Intermediate Solution (10mg/L)

Take 100 µL of the extraction substitute stock solution (5.2.3) and the target compound stock solution (5.2.5) in a 10 mL volumetric flask, and use toluene/acetone

(80/20) mixture is constant volume.

5.2.7 Phenol phenol-D6 calibration working solution (1mg/L)

Take 1000µL of calibration intermediate solution (5.2.6) in a 10mL volumetric flask, and use a toluene/acetone (80/20) mixture to make the volume constant.

6.1 Analytical balance with an accuracy of at least 0.1mg.

6.2 Glass bottle, sealable, 40mL.

6.3 Ultrasonic water bath, temperature controllable.

6.4 PTFE membrane filter, the pore width is 0.45µm.

6.5 2mL sample bottle, PTFE cap.

6.6 20mL sample bottle, polytetrafluoroethylene cap.

6.7 Gas chromatograph equipped with a mass selective detector (MSD), or other chromatographic techniques that have been confirmed to be used for this analysis.

8.1 Extraction

Weigh 1g sample into a 20mL glass bottle (6.6). Then add 9.8mL of mixed extract (5.1.6) and.200µL of extraction

Substitute working fluid (5.2.4).

Ultrasonic extraction (60+/-2)min at (60+/-5) degrees C.

Note. It has been confirmed that acetone is effective as an extraction solvent. However, its higher polarity (compared to the mixed extract) can cause a large amount of co-extraction in the extract

Compounds (such as dyes or other polar compounds such as ethylene glycol), these may interfere with the analysis.

Some polymeric materials will dissolve in the mixed extract and cause quantitative problems. In this case, methanol can be used for precipitation. Join

20mL methanol (5.1.7) precipitation at least 5min, if necessary, filter with a 0.45µm PTFE membrane filter.

8.2 Analysis

Take 1mL of the obtained extract and add 50µL of internal standard working solution (5.2.2).

According to Chapter 9, GC-MS (6.7) was used for analysis.

8.3 Calibration

For practical reasons, calibration is performed with a solution containing the target compound and extraction substitute.

At least 5 measuring points with different concentrations in the linear range. Calibrate directly with a 2mL sample bottle, see Table 1.

9.1 Measuring method

In addition to the methods described in Appendix A, other analytical methods can also be used if they reach comparable accuracy and limit of quantification (9.3.1).

The ions given in Table 2 should be used.

Examples are given in Appendix A.

9.2 Quantitative

9.2.1 Calibration curve

Use the ratio of (Ae/Ais) and (Ce/Cis) in formula (1) to establish a linear regression function.

9.2.2 Recovery rate

After using the extraction substitute, the extraction rate is calculated by formula (2).

If the extraction rate is lower than 75% or higher than 125%, the sample should be re-analyzed.

9.2.3 Determination of phenol content

Calculate the phenol content according to formula (3), expressed as mass fraction W (mg/kg).

9.3 Measurement method performance

9.3.1 Limit of quantification of GC-MS method

Taking into account the sample mass of 1g and the extraction volume of 10mL, the limit of quantification of this method should be 0.5mg/kg.

The extract is concentrated to 1mL under a gentle nitrogen flow, which can reduce the limit of quantification.

9.3.2 Tests between laboratories

Appendix B shows the results of the inter-laboratory test.