GB/T 36793-2018 in English

Standard Background and Significance

GB/T 36793—2018 was developed to address the widespread use of plasticizers in rubber and plastic materials and their potential harm to humans and the environment. With the increasing awareness of environmental protection and the improvement of regulatory requirements, it is particularly important to accurately determine the content of phthalate plasticizers.

Technical method analysis

This standard uses gas chromatography-mass spectrometry (GC-MS), which is an efficient, sensitive and highly selective analytical technique. Qualitative analysis is performed using total ion current chromatograms (TIC) and mass spectrometry (MS), and quantitative analysis is performed using selected ion detection (SIM) and external standard methods.

Detailed analysis process

1. Sample preparation

• Plastic samples: Cut and grind to a particle size of approximately 0.2 mm × 0.2 mm.
• Rubber samples: Cut and grind to a particle size of less than 2.0 mm × 2.0 mm.

2. Extraction

Using a Soxhlet extractor, plastic samples were extracted with n-hexane or a suitable solvent, and rubber samples were extracted with ether. Automatic Soxhlet extractor conditions include the control of the temperature of the heating plate and the soaking time.

3. Purification and determination

• When the concentration of the extract is low, first concentrate the solvent by rotary evaporation.
• When the solution is viscous or turbid, it is purified by solid phase extraction column.
• Finally, the volume is fixed with n-hexane and filtered before GC-MS analysis.

Quality control and result analysis

Blank test is a key step to ensure the accuracy of the experimental results. In terms of the detection limit, DINP and DIDP are 5 mg/kg, and the other plasticizers are 1 mg/kg.

Recovery and Precision

The standard stipulates that the recovery rate of phthalates is 77%~113%, ensuring the reliability and accuracy of the data.

Test report requirements

• Include information such as sample source and description, standard number, extraction method, etc.
• Report the arithmetic mean of parallel samples and record any deviations from the standard and abnormal phenomena.