GB/T 37639-2019Determination of polybrominated biphenyls and polybrominated diphenyl ethers in plastic products - Gas chromatography and mass spectrometry (English PDF)

4.1 Dichloromethane

chromatographically pure.

4.2 n-hexane

chromatographically pure.

4.3 Liquid nitrogen

industrial grade.

4.4 Polybrominated biphenyls (PBBs) standard solution

The mass concentration is 10 µg/mL.

4.5 Standard solution of polybrominated diphenyl ethers (PBDEs)

Mass concentration 5µg/mL.

4.6 Silica gel

particle size 0.063mm ~ 0.200mm, baked at 450 ° C for 24 hours before use, cooled during drying, stored in closed glass

In the bottle.

4.7 Acidified silica gel

prepared by mixing 2.24g of activated silica gel (4.6) with 1.76g of concentrated sulfuric acid.

4.8 toluene-methanol (volume ratio 10

1).

4.9 Toluene

chromatographically pure.

4.10 Methanol

chromatographically pure.

5.1

Gas chromatography-mass spectrometry (GC-MS).

5.2

Soxhlet extraction device.

5.3

Rotary evaporator.

5.4

Crusher.

5.5

Solid phase extraction device.

5.6

Constant temperature water bath (temperature accuracy is less than 1 °C).

5.7

Analytical balance (accurate to 0.0001g).

5.8

Sealed microwave extraction instrument.

5.9

Ultrasonic Extractor.

5.10 Organic phase filter membrane

0.45µm filter membrane.

7.1 Extraction

The extraction methods include the following three methods.

a) Soxhlet extraction method. accurately weigh 0.1g sample (accurate to 1mg) on an analytical balance, put it into a filter paper tube, and add 150mL

Dichloromethane solution, control the temperature of the water bath to 60 °C ± 5 °C, extract at a rate of 2 drops/s ~ 3 drops/s for more than 12h,

After cleaning, for cleaner samples, or slightly turbid, but samples that can be improved by adding methanol, spin the extract with

After the evaporator is concentrated and made up to 100 mL, the analysis is performed directly; for samples with darker colors and more impurities, the extraction solution is used.

After concentrating to a small volume with a rotary evaporator, purify it according to 7.2.

b) Microwave extraction method. accurately weigh 0.5g ~ 2g of crushed sample, accurate to 1mg, put it into the extraction tank, and accurately remove 20mL

Toluene-methanol (see 4.8), sealed in a microwave extraction apparatus (see 5.8), warmed to 115 ° C in 5 minutes, and maintained for 15 minutes

Above, cool to room temperature, completely transfer the extract, and wash the extraction tank with the extraction solvent in stages.

The extract was concentrated to 2mL ~ 3mL by an evaporator, and purified according to 7.2. For extracts that cannot be completely transferred,

In order to verify that the extraction solution is not lost during the extraction process, accurately remove 2 mL of the sample solution and purify it according to 7.2.

c) Ultrasonic extraction method. accurately weigh 0.5g (accurate to 1mg) crushed sample in glass centrifuge, add 5.0mL toluene (see

4.9). After ultrasonic extraction for 30 min, it was filtered into a 5.0 mL volumetric flask and the volume was adjusted with toluene. Pipette 100 µL of sample extract

The mobile phase was made to a constant volume of 1.0 mL, and was measured after filtration through a 0.45 µm filter. This method generally does not require purification.

Excessive, can be purified according to 7.2.

7.2 Purification

The silica gel extraction cartridge was installed on a solid-phase extraction device.First, 15 mL of a 1. 1 mixed solution of n-hexane and dichloromethane was applied to the silica gel.

The column was activated, then the concentrated sample extract was transferred to a silica gel column, and finally mixed with 120 mL of 1. 1 n-hexane and dichloromethane.

The combined solution was eluted. The eluted solution was collected, then concentrated on a rotary evaporator, and the volume was adjusted to 100 mL with the elution solvent.

7.3 GC-MS Conditions

The GC-MS conditions are as follows.

a) Chromatographic column. Quartz capillary column, 15m × 0.25mm (inner diameter) × 0.10µm, or equivalent chromatographic column;

b) Program temperature increase. keep at 100 °C for 1min, increase the temperature to 220 °C at a rate of 8 °C/min, hold it for 0.5min, and then at 20 °C/min

The temperature is raised to 320 °C for 5min;

c) Sampling method. pulse splitless, splitless time 2.0min;

d) injection volume. 1 µL;

e) inlet temperature. 280 °C;

f) Flow rate and mode. 1.8mL/min constant flow mode;

g) Carrier gas. High-purity helium, purity >=99.9999%;

h) Solvent delay. 1.5min;

i) Quadrupole temperature. 150 °C;

j) Ion source temperature. 250 ° C;

k) Ionization mode. EI, energy 70eV;

l) Mass range. 100amu ~ 1000amu.

7.4 Determination

Prepare and initialize the gas chromatograph according to the chromatographic conditions in 7.3. After the instrument reaches the set temperature, take 1 µL of standard solutions of different concentrations.

The liquid and the sample test solution for preventive treatment were measured by a gas chromatography-mass spectrometer. Based on retention time and qualitative characteristics of individual compounds

The ions are qualitatively selected, and the peak area of the ions is selected for quantification based on the quantitative characteristics. Total ion current of PBBs and PBDEs mixed standard solution

See Appendix A and Appendix B for chromatograms and selected ion chromatograms. Qualitative and quantitative selective ions for PBBs and PBDEs

Appendix C.

7.5 Blank test

A blank test is performed with the sample.

7.6 Calculation of results

Establish polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE) compounds by linear equation (1) or other suitable equations.

Calibrate the curve and determine the corresponding equation parameters a and b. The equation is shown in equation (1).

A = a × wb (1)

Where.

A --- Chromatographic peak area of each compound of polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE) in the standard solution;

w --- the content (mass fraction) of each compound of polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE) in the standard solution

Milligram per kilogram (mg/kg);

a --- the slope of the calibration curve of each compound in polybrominated biphenyls (PBB) and polybrominated diphenyl ethers (PBDE);

b --- Intercept of calibration curve of each compound in polybrominated biphenyl (PB) and polybrominated diphenyl ether (PBDEB).

Calculate the content (mass fraction) of each component in the unknown sample according to formula (2).

wi = [(As-A0-b) × V]/(a × m) (2)

Where.

wi --- the content (mass fraction) of each compound of polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE) in the sample, the unit is milligram

Per kilogram (mg/kg);

As --- chromatographic peak area of each compound of polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE) in the sample;

A0 --- chromatographic peak area of blank sample;

V --- The final constant volume of the sample, in milliliters (mL);

m --- sample mass in grams (g).

Take the arithmetic mean of two parallel determinations and round down to the whole number according to GB/T 8170 as the measurement result.