GB/T 24168-2023Determination of the content of phthalate in textile dyeing and finishing auxiliaries (English PDF)

5.1 General provisions

Unless otherwise specified, only reagents confirmed as analytical reagent and grade 3 water specified in GB/T 6682-2008 are used. The test results are determined according to the rounded value comparison method in 4.3.3 of GB/T 8170-2008.

5.2 Reagents and materials

5.2.1 Phthalate standard substances: meet the requirements of Annex A, and the content is >= 98 % (mass fraction).

5.2.2 n-hexane: chromatographically pure.

5.2.3 Acetone: chromatographically pure.

5.2.4 n-hexane-acetone mixed solvent: the volume ratio of n-hexane to acetone is 1:1.

5.3 Instruments and equipment

5.3.1 Gas chromatograph-mass spectrometer (GC/MS): equipped with electron impact (EI) ion source.

5.3.2 Chromatographic column: 50 % phenylmethylpolysiloxane stationary phase, such as 30 m × 0.25 mm × 0.25 µm or equivalent chromatographic column.

5.3.3 Micro-syringe or autosampler.

5.3.4 Analytical balance: accuracy of 0.01 mg.

5.3.5 Extractor: made of hard glass, tubular, with ground mouth and bottle stopper, 25 mL.

5.3.6 Ultrasonic generator: working frequency of 40 kHz.

5.3.7 Polytetrafluoroethylene membrane filter head: 0.45 µm.

5.3.8 Centrifuge tube with ground mouth and stopper: 10 mL.

5.3.9 Centrifuge: 4000 r/min.

5.4 Gas chromatography-mass spectrometry analysis conditions

5.5.2 Phthalate single standard intermediate solution

Pipette 0.1 mL of each phthalate single standard stock solution into a 10 mL volumetric flask, dilute to the mark with n-hexane or other suitable solvents to prepare a single standard intermediate solution. The mass concentration of diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP) solutions is 50 mg/L, and the mass concentration of the remaining substances is 10 mg/L.

NOTE: The standard intermediate solution is sealed and stored in a refrigerator at 0 °C ~ 4 °C, and the validity period is 6 months.

5.5.3 Standard working solution

Use the phthalate single standard intermediate solution to prepare a single standard working solution or a mixed standard working solution. It can prepare the appropriate concentration according to the content of the target substance in the sample.

NOTE: The standard working solution is sealed and stored in a refrigerator at 0 °C ~ 4 °C, and the validity period is 1 month.

5.5.4 Sample solution

Weigh 1.0 g of sample (accurate to 0.0001 g), place in an extractor, accurately add 10.0 mL of n-hexane-acetone mixed solution or other suitable extractant, shake well, and extract in an ultrasonic generator for 20 minutes and ensure complete extraction. Use a 0.45 µm polytetrafluoroethylene membrane filter to inject and filter the extract into a small sample bottle for chromatographic analysis.

If the sample is water-soluble, when necessary, add 2 mL of water to the sample first, shake evenly, and then add 10.0 mL of n-hexane-acetone mixed solution or other suitable extractant; if the sample is turbid after ultrasonic extraction, use a centrifugal device to centrifuge until the layers are separated and then take the upper clear liquid for analysis. Prepare a blank sample at the same time.

5.6 Determination

5.6.1 Qualitative analysis

By comparing the retention time and relative abundance of characteristic ions of the target compound in the sample and the standard working solution, it requires the signal- to-noise ratio (S/N) of the chromatographic peak of the tested specific phthalate to be greater than 3, the retention time of the specific phthalate in the sample is consistent with the retention time of the target compound in the standard solution, and the corresponding characteristic ion abundance ratio of the specific phthalate in the tested […]