Dimethylsiloxane mixed ring body (two)

4 Test method

4.

Unless otherwise specified, only reagents confirmed to be analytically pure and grade 3 water specified in GB/T6682 are used in the analysis

4.

Add a liquid laboratory sample to a 50mL colorimetric tube with a plug, and measure it axially under daylight or sunlight

4.

Measure according to the regulations of GB/T3143

4.

Measure according to the regulations of GB/T6488

4.

4.

Using gas chromatography, under selected working conditions, the sample is vaporized and separated by a chromatographic column, detected by a flame ionization detector, and quantified by area normalization

4.

4.

4.

4.

4.

4.
5.
3.
1 Gas chromatograph: equipped with a shunt device and flame ionization detector, the detection limit is less than or equal to 3×10 ^-12 g/s (sample: biphenyl);

4.
5.
3.
2 Chromatography workstation or data processor;

4.
5.
3.
3 Micro syringe: 1uL
.

4.
5.
4 Chromatographic column and typical operating conditions

The chromatographic rod recommended in this standard and typical operating conditions are shown in Table 2, and the typical chromatogram is shown in Figure 1
.
Other non-polar, weak-polar and medium-polar dimethylsiloxane capillary chromatographic columns and operating conditions that can achieve the same degree of separation can be used
.
The relative retention value of each component is shown in Table 3
.

Table 2 Chromatographic column and typical operating conditions

Table 3 Relative retention values ​​of components

4.
5.
5 Analysis steps

After starting the chromatograph, make necessary adjustments to achieve the chromatographic operating conditions in Table 2 or other suitable conditions
.
When the chromatograph reaches the set operating conditions and is stable, the sample is measured
.
Use a chromatographic data processor or a chromatographic workstation to record the peak area of ​​each component
.

Figure 1 Typical chromatogram of dimethyl siloxane mixed ring on 100% dimethyl polysiloxane capillary column

4.
5.
6 Result calculation

The mass fraction w _{i of the} total ring body or hexamethyldisiloxane , the value is expressed in %, calculated according to formula (1):

Where:

A _i — the sum of the peak areas of the components of the total ring body or the peak areas of hexamethyldisiloxane:

∑A _i — the sum of the peak areas of each component
.

Take the arithmetic average of the two parallel determination results as the determination result.
The absolute difference between the two parallel determination results should conform to: the mass fraction of the total cyclohexene is greater than 0.
10%; the mass fraction of hexamethyldisiloxane is not greater than 0.
003%
.

Related links: Dimethicone mixed ring body (1)