Appendix B
Determination of volatile substances
B.1 Range
This standard specifies the determination methods for volatile substances in silicone rubber materials and products for food contact.
This standard is applicable to the determination of volatile substances in silicone rubber materials and products for food contact.
B.2 Principle
After pretreatment of the samples of silicone rubber materials and products for food contact, the liquid loss of the samples under normal pressure and after being heated and baked for a certain temperature and time was measured to obtain the amount of volatile substances of the silicone rubber materials and products for food contact under the corresponding conditions.
B.3 Reagents and materials
B.3.1 Reagents
Water: Grade III water in compliance with GB/T 6682.
B.3.2 Materials
B.3.2.1 Containers: Surface dishes, evaporating dishes, weighing dishes, crucibles, etc.
B.3.2.2 Weighing dish: Aluminum, flat.
B.3.2.3 Dryer: Equipped with desiccant.
B.4 Instruments and Equipment
B.4.1 Electronic balance: Sensitivity is 0.1 mg.
B.4.2 Electric Heating Blower Drying Oven: Temperature control accuracy (100±2)℃, temperature control accuracy (200±3)℃.
B.5 Analysis Steps
B.5.1 Sample Pretreatment
Soak the pacifier samples in slightly boiling water for 10 minutes, stirring them from time to time during the soaking process to ensure that the samples do not touch the container walls. After soaking, take out the sample, shake off the water. If the next step of the test cannot be carried out immediately, place the sample in a desiccator for storage. Other samples do not require pretreatment.
B.5.2 Sample Preparation
Cut the sample into fragments with a length, width and thickness not exceeding 2cm each, and place them in an appropriate container, ensuring that the sample fragments do not overlap with each other. Place the container containing the sample fragments in an electric hot air drying oven at (100 ± 2)℃, dry for (60±5) minutes, then take it out and cool it in a desiccator for (60±5) minutes for determination.
B.5.3 Determination
Place the weighing dish in an electric hot air drying oven at (200±3)℃ to dry for at least 60 minutes. After taking it out, place it in a desiccator to cool for at least 60 minutes, and then weigh the mass of the empty dish (accurate to 0.1 mg). Repeat the above drying steps until the difference in the mass of the empty dishes from the previous and subsequent weighs does not exceed 2.0 mg, and record the mass of the empty dishes in m. Take approximately 10g of the sample fragments to be tested from B.5.2 and place them in a constant-weight weighing dish. Ensure that the sample fragments do not overlap with each other. Weigh the total mass m of the sample fragments and the weighing dish (accurate to 0.1mg). Place the weighing dish containing the sample fragments in an electric heating effect air drying oven at (200±3)℃, dry for (240±5) minutes, then take it out and cool it in a desiccator for (120±5) minutes. After that, weigh the total mass m(accurate to 0.1mg) of the sample fragments and the weighing dish.
B.6 Presentation of the Analysis Results
The mass of volatile substances in the sample is calculated according to formula (B.1) :
In the formula:X=(M1-M2)/(M1-M0)*100%
X - The amount of volatile substances in the sample, measured in grams per 100 grams (g/100 g);
M1 - The total mass of the sample and weighing dish before drying, in grams (g);
M2 - The total mass of the sample and weighing dish after drying, with the unit of grams (g);
M0 - The mass of the empty weighing dish, with the unit of grams (g).
The results are expressed as the arithmetic mean of two independent determination results obtained under repeatability conditions, rounded to two decimal places.
Precision B.7
When the amount of volatile substances in the sample is ≤0.2g/100g, the difference between two independent determination results obtained under repeatability conditions shall not exceed 30% of their arithmetic mean. When the amount of volatile substances in the sample is less than 0.5g /100g, the difference between two independent determination results obtained under repeatability conditions shall not exceed 20% of their arithmetic mean; when the amount of volatile substances in the sample is greater than 0.5 At g/100g, the difference between two independent determination results obtained under repeatability conditions shall not exceed 15% of their arithmetic mean.
