Determination of residual acrylonitrile monomer content in styrene-acrylonitrile copolymer by gas chromatography (1)

1 Scope

This standard specifies the method for determining the residual internal acrylonitrile monomer content in styrene - acrylonitrile copolymers and blends by gas chromatography .

2 Normative application documents

The clauses in the following documents have become clauses of this standard after being quoted in this standard

ISO2561 Plastics-Determination of Residual Styrene Monomers in Polystyrene and Impact Polystyrene-Gas Chromatography

3 Principle

Dissolve the sample with dimethylformamide.

4 Reagents

During the test, only use approved analytical reagents.

4.

4.

4.

5 Instruments

5.

Test conditions of gas chromatograph:

Chromatography: It is recommended to use stainless steel or glass tubes with a length of 1m～2m and an inner diameter of 3mm～4mm, filled with PorapakQ with a particle size of 150um～270um (that is, 50 mesh to 100 mesh)

The filling method of the chromatographic rod is not specified, but it is required to obtain a satisfactory separation effect.

Temperature of chromatographic column (including preparatory column if used): 160℃～180℃

Inlet temperature: 200℃～230℃

Detector temperature: 230℃

Carrier gas: Ammonia (or nitrogen), which meets the requirements of ISO2561

Adjust the carrier gas flow rate so that the peak time of propionitrile is 5min to 10min

Adjust the oxygen and air flow rates of the flame ionization detector to obtain the following results:

a) High sensitivity response:

b) There is a linear response in the measured range;

c) Small changes in gas flow rate have little effect on response or sensitivity

There should be a layer of polytetrafluoroethylene on each side of the silica gel pad used for sample injection to prevent the corrosion of dimethylformamide
.
If the rubber pad has only one-sided protective layer, two layers should be used.
Even so, the rubber pad must be replaced frequently.

Note: Capillary columns that can achieve the same separation effect, such as FFAP, can be used
.

5.
2 Micro syringe: the volume is 1uL to 50uL
.

5.
3 Analytical balance: accuracy 0.
5mg
.

6 Preparation of samples

Samples can be taken from powdered materials, pellets or molded articles
.
Large pieces of material should be crushed into small enough fragments to be able to weigh a sample as close as possible to 1.
0g.
The sample should not be heated during the crushing process
.

Related Links: Industrial Acrylonitrile—Determination of Copper Content Graphite Furnace Atomic Absorption Method (2)