GB/T 24281-2009Textiles - Determination of volatile organic compounds - Gas chromatography/mass spectrography (English PDF)

5.2 Internal Standard Substance

N-octane or n-heptane.

5.3 Organic Solvents

N-pentane, methanol and butanone.

5.4 Preparation of Aromatic Hydrocarbon Mixed Solution

Use weight reduction method to respectively weigh-take around 0.1 g of aromatic hydrocarbon standard substance. Place it in a 4 mL sample bottle with a stopper (6.7).

Seal it up, then, shake it well.

NOTE: this mixed solution shall be sealed and stored in a refrigerator at 0 °C ~ 4 °C; the validity period is 2 weeks.

5.5 Preparation of Standard Stock Solutions of Toluene, Vinyl-

cyclohexene, Styrene and 4-phenylcyclohexene

Transfer-take a small amount of n-pentane into a 100 mL brown volumetric flask (6.8).

Use weight reduction method to respectively weigh-take around 0.4 g (accurate to 0.2 mg) of toluene, vinyl-cyclohexene, styrene and 4-phenylcyclohexene in volumetric flasks. Use n-pentane to reach a constant volume.

NOTE: the standard stock solutions shall be sealed and stored in a refrigerator at 0 °C ~

4 °C; the validity period is 2 weeks.

5.6 Preparation of Standard Working Solutions of Toluene, Vinyl-

cyclohexene, Styrene and 4-phenylcyclohexene

Transfer-take an appropriate amount of the above-mentioned standard stock solutions (5.5) into 10 mL brown volumetric flasks (6.8). Use n-pentane to dilute to the scale, so that the concentration of the calibration working solutions is respectively: 2,000 µg/mL,

1,000 µg/mL, 500 µg/mL, 200 µg/mL, 50 µg/mL and 10 µg/mL.

NOTE: the standard working solutions shall be sealed and stored in a refrigerator at 0 °C

~ 4 °C; the validity period is 2 weeks.

5.7 Preparation of Standard Working Solutions of Vinyl Chloride and 1,3-

butadiene

Use butanone as the solvent. In accordance with the methods of 6.2.3 and 6.2.4 in

GB/T 5009.67-2003, respectively prepare standard working solutions of vinyl chloride and 1,3-butadiene with the concentration of 100 mg/mL, 50 mg/mL, 20 mg/mL, 10 mg/mL and 5 mg/mL. Prepare the solutions before usage.

NOTE: the relative density of vinyl chloride and 1,3-butadiene is respectively: 0.912 g/mL

7.2 Purification of SPME Extraction Head

Insert SPME extraction head into the gas chromatography inlet or other purification devices. At 300 °C, purify it for 60 min. Then, immediately insert the SPME extraction head into the gas chromatography inlet for GC / MS analysis, till there is no target object or non-stability interference chromatographic peak in the analysis chromatogram.

7.3 Preparation of Headspace Sampler

Use methanol to clean the inner wall of the headspace sampler (6.2) and the sample holder; dry them. After raising the temperature to 120 °C, place 2 blank test pieces (7.1), cover with the top cover; equilibrate it for 60 min. Through the sampling port on the top cover, insert the already-purified SPME extraction head (7.2) into the headspace sampler; conduct extraction for 20 min. Then, immediately insert it into the gas chromatography inlet for GC / MS analysis, till there is no target object or non- stability interference chromatographic peak in the analysis chromatogram.

8.1 Preparation of Test Pieces

From test sample, cut 2 test pieces with the area of 100 cm

2

. Accurately weigh-take its mass (accurate to 1 mg). Use aluminum foil to seal it up.

NOTE: during the preparation, appropriate measures may be adopted to avoid test piece contamination that might be caused by grease or environmental organic matters.

8.2 Determination of Standard Working Curves of Toluene, Vinyl-

cyclohexene, Styrene and 4-phenylcyclohexene

Wait till the headspace sampler (6.2) is raised to 120 °C, stack two blank test pieces (7.1) on the sample holder; cover with the top cover. Use 10 µL micro-injection needle to respectively transfer-take 4 µL of toluene, vinyl-cyclohexene, styrene and 4- phenylcyclohexene standard working solution (5.6). Through the sampling port on the top cover, promptly inject into the headspace sampler. Meanwhile, inject 4 µL of internal standard solution (5.8); equilibrate it for 60 min. Then, through the sampling port on the top cover, insert the already-purified SPME extraction head (7.2) into the headspace sampler; conduct extraction for 20 min. Then, immediately insert it into the gas chromatography inlet. In accordance with the chromatographic conditions (8.5), analyze, determine and draw a standard working curve.

8.3 Determination of Standard Working Curves of Vinyl Chloride and 1,3-

butadiene

8.3.1 In accordance with the steps of 8.2, through the sampling inlet of the headspace aromatic hydrocarbons in the chromatographic peak.

8.7 Sample Determination

Wait till the headspace sampler (6.2) is raised to 120 °C, then, stack two test pieces (8.1) on the sample holder; cover with the top cover. Through the sampling port on the top cover, inject 4 µL of the internal standard solution (5.8); equilibrate it for 60 min.

Then, through the sampling port on the top cover, insert the already-purified SPME extraction head (7.2) into the headspace sampler. Conduct extraction for 20 min, then, immediately insert it into the gas chromatographic inlet; in accordance with the chromatographic conditions (8.5), analyze it. Before the determination, the sample shall receive a blank test.

NOTE: when the sample simultaneously contains vinyl chloride and 1,3-butadiene, the selective ion scanning mode may be used for determination.

9.1 Establishment of Linear Calibration Formula

Respectively use the corresponding ratio of the peak area and mass of six monomers (vinyl chloride, 1,3-butadiene, toluene, vinyl-cyclohexene, styrene and 4- phenylcyclohexene) in the standard working solutions, and the peak area and mass of the internal standard substances. Use the least square fitting method to obtain linear calibration formula (1), where the linear correlation coefficient gamma shall be greater than

0.995.

Where,

Ai---peak area of six monomers;

As ---peak area of internal standard substances;

Ki---slope of linear calibration formula of six monomers;

mi---mass of six monomers, expressed in (mg);

ms ---mass of internal standard substances, expressed in (mg);

bi---intercept of linear calibration formula of six monomers on the Y-axis.

9.2 Calculation of Desorption

9.2.1 Calculation of desorption of vinyl chloride, 1,3-butadiene, toluene, vinyl-

Wmc ---mass concentration of total volatile organic compounds, expressed in (mg/kg);

Mc ---desorption of total volatile organic compounds, expressed in (mg);

m0---mass of test piece, expressed in (kg).