GB/T 39107-2020Determination of volatile organic compounds content for consumer products - Static headspace sampling method (English PDF)

2.1 Methanol (CH3OH)

chromatographically pure.

2.2

Benzene (C6H6), toluene (C7H8), ethylbenzene (C 8H10), m-xylene (C 8H10), p-xylene (C8H10), o-xylene (C 8H10) benzene series standard solution: 2,000 mg/L, commercially available standard substance, methanol solvent.

available standard substance, methanol solvent.

2.4 N-hexane (C 6H14) standard solution

2,000 mg/L, commercially available standard substance, methanol solvent.

2.5 Cyclohexanone (C 6H10O)

commercially available standard substance, 99.9% […]

3.4 Electronic balance

with a division value of 0.1 mg.

3.5 Micro syringe

10 µL, 50 µL.

3.6

Headspace sampling bottle capper.

3.7 Headspace bottle

with a volume of 20 mL.

3.8 Brown glass volumetric flask

5 mL, 10 mL.

4.1 Principle

The sample is placed in a closed headspace bottle and equilibrated at a specific temperature for a certain period of time, so that the target compound in the sample volatilizes and reaches dynamic equilibrium in the headspace bottle. Through the gas chromatograph - mass spectrometer, conduct separation and detection. Adopt the internal standard method for quantification.

4.2 Analytical Procedures

4.2.1 Sample processing

In terms of solid samples like wood and foaming materials: freeze and crush the sample, or cut it to a particle size of less than 2 mm; accurately weigh-take 0.02 g of the sample, place it in a headspace bottle; add 10 µL of the internal standard working solution (2.14), then, quickly seal the headspace bottle; reserve it for later testing.

In terms of samples like coatings, adhesives and inks: accurately weigh-take 0.02 g of the sample, place it in a headspace bottle; add 10 µL of the internal standard working solution (2.14), then, quickly seal the headspace bottle; reserve it for later testing.

If the content of the compound under test is excessively high in the sample, the sampling size should be adjusted as appropriate.

4.2.2 Determination conditions

4.2.2.1 Conditions of headspace sampler

The conditions of the headspace sampler include:

a) Equilibrium temperature: 150 °C;

b) Equilibrium time: 45 min;

c) Transmission line temperature: 170 °C;

d) Pressurization time: 1.0 min;

e) Needle withdrawal time: 0.2 min;

f) Injection volume: 1 mL;

g) Temperature of sample injection needle: 160 °C.

4.2.2.2 Conditions of gas chromatograph and mass spectrometer

Due to different instruments being used, the optimal analysis conditions might also be different. Hence, it is impossible to provide general parameters for instrument analysis.

The set parameters should ensure effective separation and determination of the tested components. The following parameters have been proven to be feasible:

a) Chromatographic column: DB-624 UI chromatographic column (60 m x 0.25 mm x 1.4 µm), or equivalent;

b) Program temperature: 40 °C, maintain for 2 min, then, at the rate of 5 °C/min, raise the temperature to 120 °C, maintain for 3 min; at the rate of 10 °C/min, raise the temperature to 160 °C, maintain for 1 min; at the rate of 5 °C/min, raise the temperature to 210 °C, maintain for 0 min; in the end, at the rate of

15 °C/min, raise the temperature to 230 °C, maintain for 1 min;

c) Carrier gas: high-purity helium, with a flow rate of 1 mL/min;

d) Sample inlet temperature: 250 °C;

e) Sample injection mode: split injection, with a split ratio of 1:1;

f) Interface temperature: 280 °C;

g) Detector: quadrupole mass analyzer;

h) Ionization mode: EI;

i) Ionization energy: 70 eV;

j) Ion source temperature: 230 °C;

k) Quadrupole temperature: 150 °C;

l) Solvent delay: 8 min;

m) Scanning mode: selected ion monitoring (SIM) mode; refer to Appendix A for target qualitative and quantitative ions.

4.2.3 Drawing of standard working curve

5.1 Principle

The sample is placed in a closed headspace bottle and equilibrated at a specific temperature for a certain period of time, so that the target compound in the sample volatilizes and reaches dynamic equilibrium in the headspace bottle. Through the gas chromatograph, conduct separation and detection. Adopt the internal standard method for quantification.

5.2 Analytical Procedures

5.2.1 Sample processing

Same as 4.2.1.

5.2.2 Determination conditions

5.2.2.1 Conditions of headspace sampler

Same as 4.2.2.1.

5.2.2.2 Conditions of gas chromatograph

Due to different instruments being used, the optimal analysis conditions might also be different. Hence, it is impossible to provide general parameters for instrument analysis.

The set parameters should ensure effective separation and determination of the tested components. The following parameters have been proven to be feasible:

a) Chromatographic column: same as 4.2.2.2;

b) Program temperature: same as 4.2.2.2;

c) Sample inlet temperature: 250 °C;

d) Carrier gas: nitrogen, with a flow rate of 1 mL/min;

e) Detector: equipped with a flame ionization detector (FID), 300 °C;

f) Sample injection mode: split injection, with a split ratio of 10:1.

5.2.3 Drawing of standard working curve

Respectively and accurately transfer-take 25 µL of the standard working solution at various levels (2.13) and 10 µL of the internal standard working solution (2.14) into a headspace bottle; immediately seal the headspace bottle; prepare the standard sample series with the respective target compound content of 0.1 µg, 0.5 µg, 1.0 µg, […]