GB/T 39934-2021Determination of volatile organic compounds from furniture products—Gas chromatography-mass spectrometry (English PDF)

3.1 Volatile organic compounds; VOCs

Organic compounds with a boiling point between 50°C and 260°C released from furniture or raw and auxiliary materials.

5.1 General

Unless otherwise specified, the purity of the reagents used should be chromatographically pure. If it is analytically pure, it should be purified to ensure no chromatographic analysis Impurities. The preparation used should be prepared in accordance with the provisions of GB/T 603.

5.2 Volatile Organic Compound Standard Substances

See Appendix A for the types of volatile organic compound standard substances.

5.3 Methanol (CH3OH)

It should be chromatographically pure.

5.4 Standard solution

Prepare the standard material (5.2) by yourself, and use methanol (5.3) as the dilution solvent to prepare the standard solution of the target VOCs to make the mass concentration They are 2000µg/mL, 500µg/mL, 100µg/mL, 20µg/mL, 5µg/mL and 2µg/mL respectively. For the reference material (5.2), The mixed standard solutions of benzene series, alcohols, halogenated hydrocarbons, terpenes, alkanes, aldehydes and ketones, esters, etc. can be configured according to the classification in Appendix A.

Standard solution can be configured separately. The standard solution can be stored at (4±2)°C for 1 month.

5.5 Inert gas

5.5.1 High purity nitrogen. the purity is not less than 99.999%.

5.5.2 High purity helium. the purity is not less than 99.999%.

6.1 VOCs adsorption tube

Adopt the adsorption tube matched with the thermal analysis instrument. The adsorption tube should be marked to confirm the direction of the air inlet during sampling. Adsorption tube should be installed There are at least 200mg graphitized carbon black and graphite molecular sieve composite (CarbopackB/CarbosieveTM) adsorbent, the particle size of the adsorbent can be Use a screen that passes 0.25mm~0.18mm (60 mesh to 80 mesh), or use an adsorption tube that can meet the same adsorption efficiency.

6.2 Thermal Desorber

The adsorption tube can be subjected to secondary thermal analysis, and the desorbed gas can be brought into the gas chromatograph/mass spectrometer through the inert gas.

6.3 Gas Chromatography-Mass Spectrometer (GC-MS)

Equipped with quality selective detector (MSD).

6.4 Electronic balance

Sensitivity is 0.1mg.

6.5 Constant flow gas sampler

The flow range is 0L/min~2L/min. The flow is stable and adjustable. Use soap film flowmeter to calibrate the sampling flow before and after sampling, the error should be Not more than 5%.

6.6 Climate cabin

It should meet the requirements of GB/T 31107.

7.1 Selection of samples

You can choose the whole piece of furniture, a complete set of furniture or furniture parts as samples. The composition and status of the sample should be indicated in the test report.

7.2 Pretreatment of samples

The sample to be tested should be pretreated before the test. Upholstered furniture shall be carried out in accordance with B.2.1 of GB/T 35607-2017. Wood furniture etc.

Other furniture shall be carried out in accordance with D.3.1.2 of GB/T 35607-2017.

8.1 Activation and storage of VOCs adsorption tube

The adsorption tube needs to be activated by inert gas at high temperature before use. Under the inert carrier gas flow of 50mL/min~100mL/min, the temperature The activation time is at least 5min at 280°C~300°C to remove the volatile organic compounds remaining in the adsorption tube as much as possible. After activation or make Before use, check that there is no interfering chromatographic peak.

The activated adsorption tube should be sealed with a metal screw cap and a PTFE ferrule, or it can be sealed with the adsorption tube matching the thermal desorber The components are sealed.

8.2 Release and collection of VOCs

After the sample is pretreated, it should be placed in the climate chamber within 1h for the release of VOCs. Climatic cabins for the release of VOCs from upholstered furniture The parts shall be carried out in accordance with the regulations in B.2.2~B.2.4 of GB/T 35607-2017. The climatic chamber conditions for the release of VOCs from wood furniture and other furniture are as follows

GB/T 35607-2017 stipulates D.3.1.3~D.3.1.5.

Connect the adsorption tube to the constant flow gas sampler, install the adsorption tube to the gas outlet of the climate chamber for VOCs collection, and adjust the sampler Flow rate, sampling 1L~10L gas in the flow range of 50mL/min~200mL/min (according to the sample volatile organic compound The amount of material released determines the sampling volume). During the test, record the sampling flow, sampling time, temperature and atmospheric pressure.

The release and collection conditions of the blank sample are the same as the release and collection conditions of the sample.

8.3 Analysis and test conditions

8.3.1 Thermal analysis conditions

Since the requirements for achieving thermal analysis efficiency are related to the instrument used, only the basic parameters of the second thermal analysis can be given, and the remaining parameters are set Please refer to the instruction manual of the thermal desorber. The parameters given below are basic parameters.

a) Thermal analysis temperature. 260°C~280°C;

b) Thermal analysis time. 5min~15min;

c) Thermal analysis gas flow rate. 50mL/min;

d) Cold trap trap temperature. -20°C~-10°C;

e) Transmission line temperature. 220°C~250°C;

f) Split ratio. Choose according to the quality of volatile organic compounds in the adsorption tube.

8.3.2 Gas chromatography-mass spectrometry analysis conditions

Because the test results are related to the instrument used, it is impossible to give general parameters for gas chromatography-mass spectrometry. Parameterized The principle is to obtain the best separation effect in the shortest time. The parameters given below have been tested and proved to be feasible.

a) Quartz capillary column. Polarity index is less than 10, column length is 50m~60m, inner diameter is 0.25mm, film thickness is 0.25µm, or phase Principal

b) Heating program. 40°C, hold for 1min, then increase to 100°C at a rate of 3°C/min, and then increase at a rate of 10°C/min Warm to 250°C, keep for 10min;

c) Carrier gas. high-purity helium, purity >=99.999%, flow rate 1.2mL/min;

d) Chromatography-mass spectrometry interface temperature. 260°C;

e) Ion source. electron ionization source EI, ion source temperature 230°C;

f) Ionization energy. 70eV;

g) Mass analyzer. quadrupole mass analyzer;

h) Quality scan range. 25amu~450amu;

i) Scan mode. select full scan mode.

8.4 Standard curve drawing

Use a syringe to accurately draw 1 µL of standard solutions (5.4) of different concentrations, and inject them into the activated adsorption tubes.

High-purity nitrogen purge at about 100mL/min for at least 5 minutes. Put the adsorption tube on the thermal desorber for gas chromatography mass spectrometry analysis, Qualitative standard ion, quantification by peak area or peak height method. Take the peak area after deducting the blank as the ordinate and the mass of the target substance as the abscissa to draw standard curve line. It is recommended to make a standard curve once a month, or make a standard adsorption tube of known concentration for each batch of samples, and use the standard curve to determine The deviation of the measurement result is within 15%. For a list of target volatile organic compounds in furniture, see Appendix A, typical of volatile organic compounds in furniture See Appendix B for the gas chromatography-mass spectrometry chromatogram.

8.5 Screening and analysis of samples

The analysis process of each sample adsorption tube is analyzed according to the operation steps of the standard curve.

Through the obtained full scan mass spectrum, the retention time of the target in the sample and the target in the standard series, the mass-to-charge ratio of fragment ions, and Compare its abundance and other information, compare the gas chromatography-mass spectrometry chromatogram of the sample, observe whether the sample spectrum has the characteristic group peak of the target, and compare the sample Qualitative screening and analysis of the types of volatile organic compounds.

10.1 Detection limit

The detection limit of volatile organic compounds in furniture in this method is shown in Appendix C.

10.2 Precision

In the same laboratory, the same operator uses the same equipment, according to the same test method, and compares the same test object in a short period of time.

The absolute difference between the two independent test results obtained in mutually independent tests is not more than 10% of the arithmetic mean of the two measured values, and If it is greater than 10% of the arithmetic mean of these two measured values, it is assumed that it does not exceed 5%.

10.3 Repeatability

The relative deviation of the repeatability determination of the same sample is less than 10%.